what is empirical evidence essay

Empirical evidence: A definition

Empirical evidence is information that is acquired by observation or experimentation.

The scientific method

Types of empirical research, identifying empirical evidence, empirical law vs. scientific law, empirical, anecdotal and logical evidence, additional resources and reading, bibliography.

Empirical evidence is information acquired by observation or experimentation. Scientists record and analyze this data. The process is a central part of the scientific method , leading to the proving or disproving of a hypothesis and our better understanding of the world as a result.

Empirical evidence might be obtained through experiments that seek to provide a measurable or observable reaction, trials that repeat an experiment to test its efficacy (such as a drug trial, for instance) or other forms of data gathering against which a hypothesis can be tested and reliably measured.

"If a statement is about something that is itself observable, then the empirical testing can be direct. We just have a look to see if it is true. For example, the statement, 'The litmus paper is pink', is subject to direct empirical testing," wrote Peter Kosso in " A Summary of Scientific Method " (Springer, 2011).

"Science is most interesting and most useful to us when it is describing the unobservable things like atoms , germs , black holes , gravity , the process of evolution as it happened in the past, and so on," wrote Kosso. Scientific theories , meaning theories about nature that are unobservable, cannot be proven by direct empirical testing, but they can be tested indirectly, according to Kosso. "The nature of this indirect evidence, and the logical relation between evidence and theory, are the crux of scientific method," wrote Kosso.

The scientific method begins with scientists forming questions, or hypotheses , and then acquiring the knowledge through observations and experiments to either support or disprove a specific theory. "Empirical" means "based on observation or experience," according to the Merriam-Webster Dictionary . Empirical research is the process of finding empirical evidence. Empirical data is the information that comes from the research.

Before any pieces of empirical data are collected, scientists carefully design their research methods to ensure the accuracy, quality and integrity of the data. If there are flaws in the way that empirical data is collected, the research will not be considered valid.

The scientific method often involves lab experiments that are repeated over and over, and these experiments result in quantitative data in the form of numbers and statistics. However, that is not the only process used for gathering information to support or refute a theory.

This methodology mostly applies to the natural sciences. "The role of empirical experimentation and observation is negligible in mathematics compared to natural sciences such as psychology, biology or physics," wrote Mark Chang, an adjunct professor at Boston University, in " Principles of Scientific Methods " (Chapman and Hall, 2017).

"Empirical evidence includes measurements or data collected through direct observation or experimentation," said Jaime Tanner, a professor of biology at Marlboro College in Vermont. There are two research methods used to gather empirical measurements and data: qualitative and quantitative.

Qualitative research, often used in the social sciences, examines the reasons behind human behavior, according to the National Center for Biotechnology Information (NCBI) . It involves data that can be found using the human senses. This type of research is often done in the beginning of an experiment. "When combined with quantitative measures, qualitative study can give a better understanding of health related issues," wrote Dr. Sanjay Kalra for NCBI.

Quantitative research involves methods that are used to collect numerical data and analyze it using statistical methods, ."Quantitative research methods emphasize objective measurements and the statistical, mathematical, or numerical analysis of data collected through polls, questionnaires, and surveys, or by manipulating pre-existing statistical data using computational techniques," according to the LeTourneau University . This type of research is often used at the end of an experiment to refine and test the previous research.

Identifying empirical evidence in another researcher's experiments can sometimes be difficult. According to the Pennsylvania State University Libraries , there are some things one can look for when determining if evidence is empirical:

Can the experiment be recreated and tested?
Does the experiment have a statement about the methodology, tools and controls used?
Is there a definition of the group or phenomena being studied?

The objective of science is that all empirical data that has been gathered through observation, experience and experimentation is without bias. The strength of any scientific research depends on the ability to gather and analyze empirical data in the most unbiased and controlled fashion possible.

However, in the 1960s, scientific historian and philosopher Thomas Kuhn promoted the idea that scientists can be influenced by prior beliefs and experiences, according to the Center for the Study of Language and Information .

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"Missing observations or incomplete data can also cause bias in data analysis, especially when the missing mechanism is not random," wrote Chang.

Because scientists are human and prone to error, empirical data is often gathered by multiple scientists who independently replicate experiments. This also guards against scientists who unconsciously, or in rare cases consciously, veer from the prescribed research parameters, which could skew the results.

The recording of empirical data is also crucial to the scientific method, as science can only be advanced if data is shared and analyzed. Peer review of empirical data is essential to protect against bad science, according to the University of California .

Empirical laws and scientific laws are often the same thing. "Laws are descriptions — often mathematical descriptions — of natural phenomenon," Peter Coppinger, associate professor of biology and biomedical engineering at the Rose-Hulman Institute of Technology, told Live Science.

Empirical laws are scientific laws that can be proven or disproved using observations or experiments, according to the Merriam-Webster Dictionary . So, as long as a scientific law can be tested using experiments or observations, it is considered an empirical law.

Empirical, anecdotal and logical evidence should not be confused. They are separate types of evidence that can be used to try to prove or disprove and idea or claim.

Logical evidence is used proven or disprove an idea using logic. Deductive reasoning may be used to come to a conclusion to provide logical evidence. For example, "All men are mortal. Harold is a man. Therefore, Harold is mortal."

Anecdotal evidence consists of stories that have been experienced by a person that are told to prove or disprove a point. For example, many people have told stories about their alien abductions to prove that aliens exist. Often, a person's anecdotal evidence cannot be proven or disproven.

There are some things in nature that science is still working to build evidence for, such as the hunt to explain consciousness .

Meanwhile, in other scientific fields, efforts are still being made to improve research methods, such as the plan by some psychologists to fix the science of psychology .

" A Summary of Scientific Method " by Peter Kosso (Springer, 2011)

"Empirical" Merriam-Webster Dictionary

" Principles of Scientific Methods " by Mark Chang (Chapman and Hall, 2017)

"Qualitative research" by Dr. Sanjay Kalra National Center for Biotechnology Information (NCBI)

"Quantitative Research and Analysis: Quantitative Methods Overview" LeTourneau University

"Empirical Research in the Social Sciences and Education" Pennsylvania State University Libraries

"Thomas Kuhn" Center for the Study of Language and Information

"Misconceptions about science" University of California

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What this handout is about

This handout introduces you to the wonderful world of writing sociology. Before you can write a clear and coherent sociology paper, you need a firm understanding of the assumptions and expectations of the discipline. You need to know your audience, the way they view the world and how they order and evaluate information. So, without further ado, let’s figure out just what sociology is, and how one goes about writing it.

What is sociology, and what do sociologists write about?

Unlike many of the other subjects here at UNC, such as history or English, sociology is a new subject for many students. Therefore, it may be helpful to give a quick introduction to what sociologists do. Sociologists are interested in all sorts of topics. For example, some sociologists focus on the family, addressing issues such as marriage, divorce, child-rearing, and domestic abuse, the ways these things are defined in different cultures and times, and their effect on both individuals and institutions. Others examine larger social organizations such as businesses and governments, looking at their structure and hierarchies. Still others focus on social movements and political protest, such as the American civil rights movement. Finally, sociologists may look at divisions and inequality within society, examining phenomena such as race, gender, and class, and their effect on people’s choices and opportunities. As you can see, sociologists study just about everything. Thus, it is not the subject matter that makes a paper sociological, but rather the perspective used in writing it.

So, just what is a sociological perspective? At its most basic, sociology is an attempt to understand and explain the way that individuals and groups interact within a society. How exactly does one approach this goal? C. Wright Mills, in his book The Sociological Imagination (1959), writes that “neither the life of an individual nor the history of a society can be understood without understanding both.” Why? Well, as Karl Marx observes at the beginning of The Eighteenth Brumaire of Louis Bonaparte (1852), humans “make their own history, but they do not make it just as they please; they do not make it under circumstances chosen by themselves, but under circumstances directly encountered, given and transmitted from the past.” Thus, a good sociological argument needs to balance both individual agency and structural constraints. That is certainly a tall order, but it is the basis of all effective sociological writing. Keep it in mind as you think about your own writing.

Key assumptions and characteristics of sociological writing

What are the most important things to keep in mind as you write in sociology? Pay special attention to the following issues.

The first thing to remember in writing a sociological argument is to be as clear as possible in stating your thesis. Of course, that is true in all papers, but there are a couple of pitfalls common to sociology that you should be aware of and avoid at all cost. As previously defined, sociology is the study of the interaction between individuals and larger social forces. Different traditions within sociology tend to favor one side of the equation over the other, with some focusing on the agency of individual actors and others on structural factors. The danger is that you may go too far in either of these directions and thus lose the complexity of sociological thinking. Although this mistake can manifest itself in any number of ways, three types of flawed arguments are particularly common:

The “ individual argument ” generally takes this form: “The individual is free to make choices, and any outcomes can be explained exclusively through the study of their ideas and decisions.” While it is of course true that we all make our own choices, we must also keep in mind that, to paraphrase Marx, we make these choices under circumstances given to us by the structures of society. Therefore, it is important to investigate what conditions made these choices possible in the first place, as well as what allows some individuals to successfully act on their choices while others cannot.
The “ human nature argument ” seeks to explain social behavior through a quasi-biological argument about humans, and often takes a form such as: “Humans are by nature X, therefore it is not surprising that Y.” While sociologists disagree over whether a universal human nature even exists, they all agree that it is not an acceptable basis of explanation. Instead, sociology demands that you question why we call some behavior natural, and to look into the social factors which have constructed this “natural” state.
The “ society argument ” often arises in response to critiques of the above styles of argumentation, and tends to appear in a form such as: “Society made me do it.” Students often think that this is a good sociological argument, since it uses society as the basis for explanation. However, the problem is that the use of the broad concept “society” masks the real workings of the situation, making it next to impossible to build a strong case. This is an example of reification, which is when we turn processes into things. Society is really a process, made up of ongoing interactions at multiple levels of size and complexity, and to turn it into a monolithic thing is to lose all that complexity. People make decisions and choices. Some groups and individuals benefit, while others do not. Identifying these intermediate levels is the basis of sociological analysis.

Although each of these three arguments seems quite different, they all share one common feature: they assume exactly what they need to be explaining. They are excellent starting points, but lousy conclusions.

Once you have developed a working argument, you will next need to find evidence to support your claim. What counts as evidence in a sociology paper? First and foremost, sociology is an empirical discipline. Empiricism in sociology means basing your conclusions on evidence that is documented and collected with as much rigor as possible. This evidence usually draws upon observed patterns and information from collected cases and experiences, not just from isolated, anecdotal reports. Just because your second cousin was able to climb the ladder from poverty to the executive boardroom does not prove that the American class system is open. You will need more systematic evidence to make your claim convincing. Above all else, remember that your opinion alone is not sufficient support for a sociological argument. Even if you are making a theoretical argument, you must be able to point to documented instances of social phenomena that fit your argument. Logic is necessary for making the argument, but is not sufficient support by itself.

Sociological evidence falls into two main groups:

Quantitative data are based on surveys, censuses, and statistics. These provide large numbers of data points, which is particularly useful for studying large-scale social processes, such as income inequality, population changes, changes in social attitudes, etc.
Qualitative data, on the other hand, comes from participant observation, in-depth interviews, data and texts, as well as from the researcher’s own impressions and reactions. Qualitative research gives insight into the way people actively construct and find meaning in their world.

Quantitative data produces a measurement of subjects’ characteristics and behavior, while qualitative research generates information on their meanings and practices. Thus, the methods you choose will reflect the type of evidence most appropriate to the questions you ask. If you wanted to look at the importance of race in an organization, a quantitative study might use information on the percentage of different races in the organization, what positions they hold, as well as survey results on people’s attitudes on race. This would measure the distribution of race and racial beliefs in the organization. A qualitative study would go about this differently, perhaps hanging around the office studying people’s interactions, or doing in-depth interviews with some of the subjects. The qualitative researcher would see how people act out their beliefs, and how these beliefs interact with the beliefs of others as well as the constraints of the organization.

Some sociologists favor qualitative over quantitative data, or vice versa, and it is perfectly reasonable to rely on only one method in your own work. However, since each method has its own strengths and weaknesses, combining methods can be a particularly effective way to bolster your argument. But these distinctions are not just important if you have to collect your own data for your paper. You also need to be aware of them even when you are relying on secondary sources for your research. In order to critically evaluate the research and data you are reading, you should have a good understanding of the strengths and weaknesses of the different methods.

Units of analysis

Given that social life is so complex, you need to have a point of entry into studying this world. In sociological jargon, you need a unit of analysis. The unit of analysis is exactly that: it is the unit that you have chosen to analyze in your study. Again, this is only a question of emphasis and focus, and not of precedence and importance. You will find a variety of units of analysis in sociological writing, ranging from the individual up to groups or organizations. You should choose yours based on the interests and theoretical assumptions driving your research. The unit of analysis will determine much of what will qualify as relevant evidence in your work. Thus you must not only clearly identify that unit, but also consistently use it throughout your paper.

Let’s look at an example to see just how changing the units of analysis will change the face of research. What if you wanted to study globalization? That’s a big topic, so you will need to focus your attention. Where would you start?

You might focus on individual human actors, studying the way that people are affected by the globalizing world. This approach could possibly include a study of Asian sweatshop workers’ experiences, or perhaps how consumers’ decisions shape the overall system.

Or you might choose to focus on social structures or organizations. This approach might involve looking at the decisions being made at the national or international level, such as the free-trade agreements that change the relationships between governments and corporations. Or you might look into the organizational structures of corporations and measure how they are changing under globalization. Another structural approach would be to focus on the social networks linking subjects together. That could lead you to look at how migrants rely on social contacts to make their way to other countries, as well as to help them find work upon their arrival.

Finally, you might want to focus on cultural objects or social artifacts as your unit of analysis. One fine example would be to look at the production of those tennis shoes the kids seem to like so much. You could look at either the material production of the shoe (tracing it from its sweatshop origins to its arrival on the showroom floor of malls across America) or its cultural production (attempting to understand how advertising and celebrities have turned such shoes into necessities and cultural icons).

Whichever unit of analysis you choose, be careful not to commit the dreaded ecological fallacy. An ecological fallacy is when you assume that something that you learned about the group level of analysis also applies to the individuals that make up that group. So, to continue the globalization example, if you were to compare its effects on the poorest 20% and the richest 20% of countries, you would need to be careful not to apply your results to the poorest and richest individuals.

These are just general examples of how sociological study of a single topic can vary. Because you can approach a subject from several different perspectives, it is important to decide early how you plan to focus your analysis and then stick with that perspective throughout your paper. Avoid mixing units of analysis without strong justification. Different units of analysis generally demand different kinds of evidence for building your argument. You can reconcile the varying levels of analysis, but doing so may require a complex, sophisticated theory, no small feat within the confines of a short paper. Check with your instructor if you are concerned about this happening in your paper.

Typical writing assignments in sociology

So how does all of this apply to an actual writing assignment? Undergraduate writing assignments in sociology may take a number of forms, but they typically involve reviewing sociological literature on a subject; applying or testing a particular concept, theory, or perspective; or producing a small-scale research report, which usually involves a synthesis of both the literature review and application.

The critical review

The review involves investigating the research that has been done on a particular topic and then summarizing and evaluating what you have found. The important task in this kind of assignment is to organize your material clearly and synthesize it for your reader. A good review does not just summarize the literature, but looks for patterns and connections in the literature and discusses the strengths and weaknesses of what others have written on your topic. You want to help your reader see how the information you have gathered fits together, what information can be most trusted (and why), what implications you can derive from it, and what further research may need to be done to fill in gaps. Doing so requires considerable thought and organization on your part, as well as thinking of yourself as an expert on the topic. You need to assume that, even though you are new to the material, you can judge the merits of the arguments you have read and offer an informed opinion of which evidence is strongest and why.

Application or testing of a theory or concept

The application assignment asks you to apply a concept or theoretical perspective to a specific example. In other words, it tests your practical understanding of theories and ideas by asking you to explain how well they apply to actual social phenomena. In order to successfully apply a theory to a new case, you must include the following steps:

First you need to have a very clear understanding of the theory itself: not only what the theorist argues, but also why they argue that point, and how they justify it. That is, you have to understand how the world works according to this theory and how one thing leads to another.
Next you should choose an appropriate case study. This is a crucial step, one that can make or break your paper. If you choose a case that is too similar to the one used in constructing the theory in the first place, then your paper will be uninteresting as an application, since it will not give you the opportunity to show off your theoretical brilliance. On the other hand, do not choose a case that is so far out in left field that the applicability is only superficial and trivial. In some ways theory application is like making an analogy. The last thing you want is a weak analogy, or one that is so obvious that it does not give any added insight. Instead, you will want to choose a happy medium, one that is not obvious but that allows you to give a developed analysis of the case using the theory you chose.
This leads to the last point, which is the analysis. A strong analysis will go beyond the surface and explore the processes at work, both in the theory and in the case you have chosen. Just like making an analogy, you are arguing that these two things (the theory and the example) are similar. Be specific and detailed in telling the reader how they are similar. In the course of looking for similarities, however, you are likely to find points at which the theory does not seem to be a good fit. Do not sweep this discovery under the rug, since the differences can be just as important as the similarities, supplying insight into both the applicability of the theory and the uniqueness of the case you are using.

You may also be asked to test a theory. Whereas the application paper assumes that the theory you are using is true, the testing paper does not makes this assumption, but rather asks you to try out the theory to determine whether it works. Here you need to think about what initial conditions inform the theory and what sort of hypothesis or prediction the theory would make based on those conditions. This is another way of saying that you need to determine which cases the theory could be applied to (see above) and what sort of evidence would be needed to either confirm or disconfirm the theory’s hypothesis. In many ways, this is similar to the application paper, with added emphasis on the veracity of the theory being used.

The research paper

Finally, we reach the mighty research paper. Although the thought of doing a research paper can be intimidating, it is actually little more than the combination of many of the parts of the papers we have already discussed. You will begin with a critical review of the literature and use this review as a basis for forming your research question. The question will often take the form of an application (“These ideas will help us to explain Z.”) or of hypothesis testing (“If these ideas are correct, we should find X when we investigate Y.”). The skills you have already used in writing the other types of papers will help you immensely as you write your research papers.

And so we reach the end of this all-too-brief glimpse into the world of sociological writing. Sociologists can be an idiosyncratic bunch, so paper guidelines and expectations will no doubt vary from class to class, from instructor to instructor. However, these basic guidelines will help you get started.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Cuba, Lee. 2002. A Short Guide to Writing About Social Science , 4th ed. New York: Longman.

Lunsford, Andrea A. 2015. The St. Martin’s Handbook , 8th ed. Boston: Bedford/St Martin’s.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Ruszkiewicz, John J., Christy Friend, Daniel Seward, and Maxine Hairston. 2010. The Scott, Foresman Handbook for Writers , 9th ed. Boston: Pearson Education.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Psychology 124: Empirical Research Essay

Empirical Article Video

What is Empirical Research?

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Finding Journal Articles
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Designing Empirical Research
Writing the Empirical Paper

Empirical Research consists of experiments that rely on observation and measurement. Empirical research uses specific methods to test out theories and hypotheses (expectations) using real data instead of hunches or observations. This type of research is easily identifiable as it always consists of the following pieces of information:

A distinct research question (usually in the abstract)
A clear "Methods" section that can be replicated for others wanting to do the experiment
A conclusion based on the data collected from the methods used

This Guide will serve to offer a basic understanding on how to approach empirical research via Reading the Empirical Research Paper, Designing Empirical Research, and Writing an Empirical Paper.

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Guided Search: Finding Empirical Research Articles This is a hands-on tutorial that will allow you to use your own search terms to find resources.

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Sometimes you may be asked to find and use empirical research. If you aren't sure what is and is not empirical research, this might seem scary. We are here to help.

Note: while this guide is designed to help you understand and find empirical research, you should always default to your instructor's definition if they provide one and direct any specific questions about whether a source fits that definition to your instructor.

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In this guide, you will learn:

The definition and characteristics of empirical research.
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15 Empirical Evidence Examples

empirical evidence examples and definition, explained below.

The term empirical evidence refers to the attainment of knowledge through observation, measurement, or experimentation ( also known as empiricism ). It is accumulated through systematic observations of phenomena in natural or laboratory setting.

One of the key standards of empirical evidence in academic research is that the results can be tested and verified by others. This can increase confidence in the conclusion and demonstrate that there is substantial evidence to accept something as a natural fact.

By contrast, anecdotal evidence , which is considered unclear and open to bias, might be a form of one-off evidence that wouldn’t be accepted unless it’s replicable. Confidence in the conclusion of anecdotal evidence is minimal.

Empirical Evidence Examples

Quantitative Data: Quantitative data is numerical data obtained through measurement, counting, or statistical analysis. An example is a person’s test scores, which are used as empirical evidence that can get you into a prestigious university. The strength of this type of data is that it tends to be objective, meaning it is less disputable than qualitative data.
Qualitative Data : Qualitative data is non-numerical data that captures the characteristics or properties of something. Examples include interview transcripts, field notes, and descriptions of behaviors or events. Its strength is that it can lead to in-depth explanations and understandingsthat quantitative data often cannot support.
Survey Data (Quantitative): Survey data, such as polling data in the lead up to an election, can be used as a form of empirical evidence if the study is reliable and valid. When the survey size is sufficient and population sample is sufficiently uniform, the data may be able to make population-wide predications about society and social views.
Data from Naturalistic Observation (Qualitative): Naturalistic observations are observations that we can make in the real world, not just in a lab environment. It can pass as empirical evidence if it’s repeatable over time and renders similar results. However, if the observation is made only once and future studies do not support claims made by the original observer, it may slip into the category of anecdotal evidence.
Case Study Data (Qualitative): Sometimes the first step to understanding a psychological disorder is to thoroughly examine how it is manifest in a single individual. This is referred to as a case study. This data is empirical and may be very sound, but its lack of population-level relevance limits is usability.
Textual Data (Quantitative or Qualitative): Although it is not possible to read people’s minds yet, the next best thing is to ask people to write their thoughts down on paper. Those words can then be coded along a variety of dimensions to develop trends across a textual dataset ( also known as textual analysis and thematic analysis).
Experimental Lab Data (Quantitative) : Randomly assigning research participants to receive different treatments is a hallmark of scientific research. By manipulating the level of one variable and observing changes in another, the researcher can draw conclusions regarding causality. Many consider this type of research as the most scientifically sound method of attaining empirical evidence.
Longitudinal Research Data (Quantitative or Qualitative): This strategy for acquiring empirical evidence involves collecting data on a particular trait over a long period of time. Researchers will administer the same measurement tool at different points in the participants’ lifespan. This can provide valuable clues regarding the stability of personality characteristics or intellectual abilities.
Cross-sectional Data (Quantitative or Qualitative): Cross-sectional data is data collected from different subjects at a single point in time. For example, a national census usually generates a cross-sectional dataset of a nation’s population at a specific point in time by asking everyone to complete the census on the same day.
Historical Data (Quantitative or Qualitative) : Historical data is empirical evidence collected from past records or documents that can provide valuable context and insight into past events or societal trends. Examples include analyzing economic data from past decades to understand the causes of financial crises or examining the diaries of individuals who lived through significant historical events to gain a deeper understanding of their experiences.
Meta-Analysis Data (Generally Quantitative) : Meta-analysis is a quantitative technique that combines the results of multiple studies on a similar topic to derive an overall conclusion. This type of empirical evidence can provide a more reliable and generalizable understanding of a phenomenon by aggregating the findings of individual studies, reducing the influence of individual study biases, and increasing statistical power.
Ethnographic Data (Qualitative) : Ethnographic data is a form of qualitative data that provides evidence recorded by an anthropologist or similar researcher. While this data gives extremely in-depth understandings (often called ‘think descriptions’), its inability to be replicated means it lacks the authority of many other types of empirical research provided in this list. Examples include studying the daily lives of a remote tribe or exploring the workplace culture of a specific organization.
Computer Simulation Data (Quantitative) : Computer simulations can be used to model complex systems or processes, providing empirical evidence that may not be easily obtained through direct observation or experimentation. Examples include modeling the spread of infectious diseases to inform public health interventions, or simulating the effects of climate change on ecosystems.
Physiological Measurement Data (Quantitative) : Physiological measurements are the empirical data that result from the recording of physical or biological signals from the body. This can provide evidence about a person’s physical state and whether it fits within physiological norms required for healthy living. Examples include measuring heart rate or skin conductance to assess stress levels.
Cultural Artifacts (Quantitative or Qualitative) : Cultural artifacts and provide powerful empirical evidence about past cultures. For example, the etchings of Aboriginal rock art in Australia has been valuable in providing clear evidence about the historical longevity of the world’s oldest continuous culture.

Case Studies of Empirical Evidence

1. evidence on who shares their passwords.

Evidence Collected by: Surveys

We all know that sharing passwords is risky. Experts would like to know who is most likely to engage in this risky behavior. As a group of these professionals sit around the table debating the issue, they quickly realize that everyone can provide good arguments to support their opinion.

So, how can this question be answered objectively?

The answer: through the scientific method .

To this end, Whitty et al. (2015) measured several personality characteristics of 630 internet users in the UK. Participants were administered questionnaires that assessed Impulsivity, Self-monitoring, and Locus of Control.

Age and knowledge of cyber security issues were also measured.

The results were sometimes surprising:

Younger people were more likely to share passwords than older people.
Those who scored high on a lack of perseverance (i.e., impulsivity) were more likely to share passwords.
Knowledge about cybersecurity did not distinguish between those who share passwords and those who do not share passwords.

The researchers concluded that:

“psychology plays an important role in providing answers to why individuals engage in cyber security practices” (p. 6).

It should be noted that several of the researchers’ hypotheses were not supported by the data. This points to a key reason empirical evidence is so valuable.

2. Linguistic Inquiry and Word Count (LIWC)

Evidence Collected by: Text Analysis

Language is the most common way that people communicate their internal thoughts and emotions. Language is key to business, relationships, scientific innovation and nearly every facet of human existence.

Studying people through language is the way that cognitive, clinical, and social psychologist try to understand human behavior .

Today, communication via texting has never been easier, offering researchers an opportunity like never before. In the old day, text analysis was conducted by hand. Weintraub (1981, 1989) pioneered this approach by hand, analyzing political speeches and medical interviews.

Tausczik and Pennebaker’s (2010) pay respects to Weintraub’s work:

“He noticed that first-person singular pronouns (e.g., I, me, my) were reliably linked to people’s levels of depression. Although his methods were straightforward and his findings consistently related to important outcome measures, his work was largely ignored” (p. 26).

Fortunately, the volume of texts today can be handled with the use of linguistic technology.

The LIWC is unique in that it has the capability of analyzing text that can

“…provide important psychological cues to their thought processes, emotional states, intentions, and motivations…that reflect language correlates of attentional focus, emotional state, social relationships, thinking styles, and individual differences” (p. 37).

Human coding is subject to bias, but empirical evidence via computer technology is much more objective.

3. Measuring Neural Activity as Empirical Evidence

Evidence collected by: Physiological instruments

One of the most common methods of measuring the brain’s neural activity in psychological research is the EEG (electroencephalogram). A few electrodes attached to the scalp can measure this activity in real time.

This kind of data collection technique has allowed researchers to study a wide range of psychological phenomena, such as memory, attention span, and emotions.

In one interesting application, Wong et al. (2007) examined if music-related experience could enhance the processing of a tonal language such as Mandarin.

After all, music involves a lot of tones, as does Mandarin. Therefore, it would seem logical that musicians would be better at processing the sounds of Mandarin than non-musicians.

So, musicians and non-musicians watched a video that contained audio recordings of Mandarin while EEG data were collected.

The results showed that the auditory brainstem regions of musicians

“…showed more faithful representation of the stimulus…Musicians showed significantly better identification and discrimination” (p. 421).

More simply put, the brains of musicians encoded the tones of Mandarin more accurately than the brains of non-musicians.

When empirical evidence is gathered using high-tech equipment, it lends a lot of credibility to the findings.

4. Reaction Time and Semantic Memory

Evidence collected by: Computational data

A frequently used measure of cognitive processing is called “reaction time.” This is a precise measurement of how long it takes for a person to process a specific piece of information.

For example, a research participant is presented with two words that are either related or unrelated.

If the two words are related, then they press one key. If the words are unrelated, then they press a different key.

The computer records how long it takes between the presentation of the words and the key press.

In one of the most influential studies in cognitive psychology , Collins and Loftus (1975) built a foundation of evidence suggesting that semantic information is stored in memory based on strengths of associations.

The reaction time of processing words that were related was much faster than words unrelated. This is because related words are more strongly connected in the memory network:

“The more properties two concepts have in common, the more links there are between the two nodes via these properties and the more closely related are the concepts…When a concept is processed (or stimulated), activation spreads out along the paths of the network in a decreasing gradient” (p. 411).

Empirical evidence in the form of reaction time is not subject to bias and the precision of measurement is quite impressive.

5. Classroom Décor and Learning

Evidence collected by: Naturalistic observation

Most teachers enjoy decorating the classroom environment with educational posters, student artwork, and theme-based materials. But if you were to tell them that those decorations actually impair learning, it might be a tough sell.

However, Fisher et al. (2014) have empirical evidence suggesting this is a real possibility.

Visual stimuli can be distracting, especially to young children. They already have short attention spans.

To put the hypothesis to the test, 24 kindergarten students participated in six lessons over a two-week period; the classroom was either fully decorate or sparsely decorated.

The lessons were recorded and coded for on-task and off-task behaviors. In addition, students took a test immediately after each lesson.

“…spent significantly more instructional time off task in the decorated-classroom condition than in the sparse-classroom condition…learning scores were higher in the sparse-classroom condition than in the decorated-classroom condition” (p. 6).

Empirical evidence isn’t perfect, and every study has limitations, but it is far more objective than opinions based on subjective judgements.

Empirical evidence is attained objectively through methods that adhere to rigorous scientific standards.

The precision of empirical evidence is quite wide. On one end of the continuum, data collected from surveys simply involves participants circling a number that is supposed to reflect their attitude.

On the other end, computer programs can be designed that track how long it takes a person to process a stimulus down to milliseconds.

But perhaps the greatest value of empirical evidence is that it can resolve debates. Smart people can generate convincing arguments to support their opinions on either side of an issue.

However, evidence that comes from scientific methods can settle those debates. Even if it takes several studies to arrive at a firm conclusion, the end result helps move science forward.

Collins, A. M., & Quillian, M. R. (1969). Retrieval time from semantic memory . Journal of Verbal Learning and Verbal Behavior , 8 (2), 240-247.

Collins, W. M., & Loftus, E. F. (1975). A spreading-activation theory of semantic processing. Psychological Review, 82 (6), 407-428.

Fisher, A. V., Godwin, K. E., & Seltman, H. (2014). Visual environment, attention allocation, and learning in young children: When too much of a good thing may be bad. Psychological Science , 25 (7), 1362-1370.

Hacking, I. (1983). Representing and intervening . Cambridge: Cambridge University Press.

Malik, S. (2017). Observation versus experiment: An adequate framework for analysing scientific experimentation? Journal for General Philosophy of Science, 48 , 71–95. https://doi.org/10.1007/s10838-016-9335-y

Iliev, R., Dehghani, M., & Sagi, E. (2015). Automated text analysis in psychology: Methods, applications, and future developments. Language and Cognition , 7 (2), 265-290.

Tausczik, Y. R., & Pennebaker, J. W. (2010). The psychological meaning of words: LIWC and computerized text analysis methods. Journal of Language and Social Psychology , 29 (1), 24-54.

Weintraub, W. (1981). Verbal behavior: Adaptation and psychopathology . New York: Springer.

Weintraub, W. (1989). Verbal behavior in everyday life . New York: Springer

Whitty, M., Doodson, J., Creese, S., & Hodges, D. (2015). Individual differences in cyber security behaviors: an examination of who is sharing passwords. Cyberpsychology, Behavior, and Social Networking , 18 (1), 3-7.

Wong, P. C., Skoe, E., Russo, N. M., Dees, T., & Kraus, N. (2007). Musical experience shapes human brainstem encoding of linguistic pitch patterns. Nature Neuroscience , 10 (4), 420–422. https://doi.org/10.1038/nn1872

Dave Cornell (PhD)

Dr. Cornell has worked in education for more than 20 years. His work has involved designing teacher certification for Trinity College in London and in-service training for state governments in the United States. He has trained kindergarten teachers in 8 countries and helped businessmen and women open baby centers and kindergartens in 3 countries.

Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 25 Positive Punishment Examples
Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 25 Dissociation Examples (Psychology)
Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 15 Zone of Proximal Development Examples
Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ Perception Checking: 15 Examples and Definition

Chris Drew (PhD)

This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

Chris Drew (PhD) #molongui-disabled-link 25 Positive Punishment Examples
Chris Drew (PhD) #molongui-disabled-link 25 Dissociation Examples (Psychology)
Chris Drew (PhD) #molongui-disabled-link 15 Zone of Proximal Development Examples
Chris Drew (PhD) #molongui-disabled-link Perception Checking: 15 Examples and Definition

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Rationalism vs. Empiricism

In its most general terms, the dispute between rationalism and empiricism has been taken to concern the extent to which we are dependent upon experience in our effort to gain knowledge of the external world. It is common to think of experience itself as being of two kinds: sense experience, involving our five world-oriented senses, and reflective experience, including conscious awareness of our mental operations. The distinction between the two is drawn primarily by reference to their objects: sense experience allows us to acquire knowledge of external objects, whereas our awareness of our mental operations is responsible for the acquisition of knowledge of our minds. In the dispute between rationalism and empiricism, this distinction is often neglected; rationalist critiques of empiricism usually contend that the latter claims that all our ideas originate with sense experience.

It is generally agreed that most rationalists claim that there are significant ways in which our concepts and knowledge are gained independently of sense experience. To be a rationalist, however, does not require one to claim that our knowledge is acquired independently of any experience: at its core, the Cartesian Cogito depends on our reflective, intuitive awareness of the existence of occurrent thought. Rationalists generally develop their view in two steps. First, they argue that there are cases where the content of our concepts or knowledge outstrips the information that sense experience can provide. Second, they construct accounts of how reason, in some form or other, provides that additional information about the external world.

Most empiricists present complementary lines of thought. First, they develop accounts of how experience alone -- sense experience, reflective experience, or a combination of the two -- provides the information that rationalists cite, insofar as we have it in the first place. Second, while empiricists attack the rationalists’ accounts of how reason is a primary source of concepts or knowledge, they show that reflective understanding can and usually does supply some of the missing links (famously, Locke believed that our idea of substance, in general, is a composite idea, incorporating elements derived from both sensation and reflection, e.g. Essay, 2.23.2).

The distinction between rationalism and empiricism is not without problems. One of the main issues is that almost no author falls neatly into one camp or another: it has been argued that Descartes, for instance, who is commonly regarded as a representative rationalist (at least with regard to metaphysics), had clear empiricist leanings (primarily with regard to natural philosophy, where sense experience plays a crucial role, according to Clarke 1982). Conversely, Locke, who is thought to be a paradigmatic empiricist, argued that reason is on equal footing with experience, when it comes to the knowledge of certain things, most famously of moral truths ( Essay, 4.3.18). In what follows, we clarify what this distinction has traditionally been taken to apply to, as well as point out its (by now) widely-recognized shortcomings.

1.1 Rationalism

1.2 empiricism, 2. the intuition/deduction thesis, 3. the innate knowledge thesis, 4. the innate concept thesis, other internet resources, related entries, 1. introduction.

The dispute between rationalism and empiricism takes place primarily within epistemology, the branch of philosophy devoted to studying the nature, sources, and limits of knowledge. Knowledge itself can be of many different things and is usually divided among three main categories: knowledge of the external world, knowledge of the internal world or self-knowledge, and knowledge of moral and/or aesthetical values. We may find that there are category-specific conditions that must be satisfied for knowledge to occur and that it is easier or more difficult to shape certain questions and answers, depending on whether we focus on the external world or on the values. However, some of the defining questions of general epistemology include the following.

What is the nature of propositional knowledge, knowledge that a particular proposition about the world, ourselves, morality, or beauty is true?

To know a proposition, we must believe it and it must be true, but something more is required, something that distinguishes knowledge from a lucky guess. Let’s call this additional element ‘warrant’. A good deal of philosophical work has been invested in trying to determine the nature of warrant.

How can we gain knowledge?

We can form true beliefs just by making lucky guesses. How to gain warranted beliefs is less clear. Moreover, to know the external world or anything about beauty, for instance, we must be able to think about the external world or about beauty, and it is unclear how we gain the concepts we use in thought or what assurance, if any, we have that the ways in which we divide up the world using our concepts correspond to divisions that actually exist.

What are the limits of our knowledge?

Some aspects of the external world, ourselves, or the moral and aesthetical values may be within the limits of our thought but beyond the limits of our knowledge; faced with competing descriptions of them, we cannot know which description is true. Some aspects of the external world, ourselves, or the moral and aesthetical values may even be beyond the limits of our thought, so that we cannot form intelligible descriptions of them, let alone know that a particular description is true.

The disagreement between rationalism and empiricism primarily concerns the second question, regarding the sources of our concepts and knowledge. In some instances, the disagreement on this topic results in conflicting responses to the other questions as well. The disagreement may extend to incorporate the nature of warrant or where the limits of our thought and knowledge are. Our focus here will be on the competing rationalist and empiricist responses to the second question.

There are three main theses that are usually seen as relevant for drawing the distinction between rationalism and empiricism, with a focus on the second question. While the first thesis has been traditionally seen as distinguishing between rationalism and empiricism, scholars now mostly agree that most rationalists and empiricists abide by the so-called Intuition/Deduction thesis , concerning the ways in which we become warranted in believing propositions in a particular subject area.

The Intuition/Deduction Thesis : Some propositions in a particular subject area, S, are knowable by us by intuition alone; still others are knowable by being deduced from intuited propositions.

Intuition is a form of direct, immediate insight. Intuition has been likened to (a sort of internal) perception by most rationalists and empiricists alike. Intellectually grasping a proposition, we just “see” it to be true in such a way as to form a true, warranted belief in it. (As discussed in Section 2 below, the nature of this intellectual “seeing” needs explanation.) Deduction is a process in which we derive conclusions from intuited premises through valid arguments, ones in which the conclusion must be true if the premises are true. We intuit, for example, that the number three is prime and that it is greater than two. We then deduce from this knowledge that there is a prime number greater than two. Intuition and deduction thus provide us with knowledge that is independent, for its justification, of experience. This type of knowledge, since Kant, is commonly called “ a priori ”.

We can generate different versions of the Intuition/Deduction thesis by substituting different subject areas for the variable ‘S’. Several rationalists and empiricists take mathematics to be knowable by intuition and deduction. Some place ethical truths in this category. Some include metaphysical claims, such as that God exists, we have free will, and our mind and body are distinct substances.

The second thesis that is relevant to the distinction between rationalism and empiricism is the Innate Knowledge thesis .

The Innate Knowledge Thesis : We have knowledge of some truths in a particular subject area, S, as part of our nature.

The Innate Knowledge thesis asserts the existence of knowledge whose source is our own nature: we are born with this knowledge; it doesn’t depend, for its justification, on our accessing it via particular experiences. Our innate knowledge is not learned through either experience or intuition/deduction. It is just part of our nature. Experiences may trigger a process by which we bring this knowledge to consciousness, but these experiences do not provide us with the knowledge itself. It has in some way been with us all along. According to some rationalists, we gained the knowledge in an earlier existence. According to others, God provided us with it at creation. Still others say it is part of our nature through natural selection.

We get different versions of the Innate Knowledge thesis by substituting different subject areas for the variable ‘S’. The more subjects included within the range of the thesis or the more controversial the claim to have knowledge in them, the more radical the form of rationalism. Stronger and weaker understandings of warrant yield stronger and weaker versions of the thesis as well. Empiricists reject this thesis: Locke, for instance, dedicates the whole first book of the Essay to show that such knowledge, even if it existed, would be of little use to us.

The third important thesis that is relevant to the distinction between rationalism and empiricism is the Innate Concept thesis.

The Innate Concept Thesis : We have some of the concepts we employ in a particular subject area, S, as part of our rational nature.

According to the Innate Concept thesis, some of our concepts are not gained from experience. They are part of our rational nature in such a way that, while sense experiences may trigger a process by which they are brought to consciousness, experience does not provide the concepts or determine the information they contain. Some claim that the Innate Concept thesis is entailed by the Innate Knowledge Thesis; a particular instance of knowledge can only be innate if the concepts that are contained in the known proposition are also innate. This is Locke’s position ( Essay , 1.4.1). Others, such as Carruthers, argue against this connection (1992, pp. 53–54). The content and strength of the Innate Concept thesis varies with the concepts claimed to be innate. The more a concept seems removed from experience and the mental operations we can perform on experience the more plausibly it may be claimed to be innate. Since we do not experience perfect triangles but do experience pains, our concept of the former is a more promising candidate for being innate than our concept of the latter.

The Intuition/Deduction thesis, the Innate Knowledge thesis, and the Innate Concept thesis are essential to rationalism. Since the Intuition/Deduction thesis is equally important to empiricism, the focus in what follows will be on the other two theses. To be a rationalist is to adopt at least one of them: either the Innate Knowledge thesis, regarding our presumed propositional innate knowledge, or the Innate Concept thesis, regarding our supposed innate knowledge of concepts.

Rationalists vary the strength of their view by adjusting their understanding of warrant. Some take warranted beliefs to be beyond even the slightest doubt and claim that intuition provide beliefs of this high epistemic status. Others interpret warrant more conservatively, say as belief beyond a reasonable doubt, and claim that intuition provide beliefs of that caliber. Still another dimension of rationalism depends on how its proponents understand the connection between intuition, on the one hand, and truth, on the other. Some take intuition to be infallible, claiming that whatever we intuit must be true. Others allow for the possibility of false intuited propositions.

Two other closely related theses are generally adopted by rationalists, although one can certainly be a rationalist without adopting either of them. The first is that sense experience cannot provide what we gain from reason.

The Indispensability of Reason Thesis : The knowledge we gain in subject area, S, by intuition and deduction, as well as the ideas and instances of knowledge in S that are innate to us, could not have been gained by us through sense experience.

The second is that reason is superior to sense experience as a source of knowledge.

The Superiority of Reason Thesis : The knowledge we gain in subject area S by intuition and deduction or have innately is superior to any knowledge gained by sense experience.

How reason is superior needs explanation, and rationalists have offered different accounts. One view, generally associated with Descartes ( Rules, Rule II and Rule III, pp. 1–4), is that what we know by intuition is certain, beyond even the slightest doubt, while what we believe, or even know, on the basis of sense experience is at least somewhat uncertain. Another view, generally associated with Plato ( Republic 479e-484c), locates the superiority of a priori knowledge in the objects known. What we know by reason alone, a Platonic form, say, is superior in an important metaphysical way, e.g. unchanging, eternal, perfect, a higher degree of being, to what we are aware of through sense experience.

Most forms of rationalism involve notable commitments to other philosophical positions. One is a commitment to the denial of scepticism for at least some area of knowledge. If we claim to know some truths by intuition or deduction or to have some innate knowledge, we obviously reject scepticism with regard to those truths. Rationalism in the form of the Intuition/Deduction thesis is also committed to epistemic foundationalism, the view that we know some truths without basing our belief in them on any others and that we then use this foundational knowledge to know more truths.

Empiricists also endorse the Intuition/Deduction thesis, but in a more restricted sense than the rationalists: this thesis applies only to relations of the contents of our minds, not also about empirical facts, learned from the external world. By contrast, empiricists reject the Innate Knowledge and Innate Concept theses. Insofar as we have knowledge in a subject, our knowledge is gained , not only triggered, by our experiences, be they sensorial or reflective. Experience is, thus, our only source of ideas. Moreover, they reject the corresponding version of the Superiority of Reason thesis. Since reason alone does not give us any knowledge, it certainly does not give us superior knowledge. Empiricists need not reject the Indispensability of Reason thesis, but most of them do.

The main characteristic of empiricism, however, is that it endorses a version of the following claim for some subject area:

The Empiricism Thesis : We have no source of knowledge in S or for the concepts we use in S other than experience.

To be clear, the Empiricism thesis does not entail that we have empirical knowledge. It entails that knowledge can only be gained, if at all , by experience. Empiricists may assert, as some do for some subjects, that the rationalists are correct to claim that experience cannot give us knowledge. The conclusion they draw from this rationalist lesson is that we do not know at all. This is, indeed, Hume's position with regard to causation, which, he argues, is not actually known, but only presupposed to be holding true, in virtue of a particular habit of our minds.

We have stated the basic claims of rationalism and empiricism so that each is relative to a particular subject area. Rationalism and empiricism, so relativized, need not conflict. We can be rationalists in mathematics or a particular area of mathematics and empiricists in all or some of the physical sciences. Rationalism and empiricism only conflict when formulated to cover the same subject. Then the debate, Rationalism vs. Empiricism, is joined. The fact that philosophers can be both rationalists and empiricists has implications for the classification schemes often employed in the history of philosophy, especially the one traditionally used to describe the Early Modern Period of the seventeenth and eighteenth centuries leading up to Kant. It is standard practice to group the philosophers of this period as either rationalists or empiricists and to suggest that those under one heading share a common agenda in opposition to those under the other. Thus, Descartes, Spinoza and Leibniz are the Continental Rationalists in opposition to Locke, Hume, and Reid, the British Empiricists. Such general classification schemes should only be adopted with great caution. The views of the individual philosophers are a lot more subtle and complex than the simple-minded classification suggests. (See Loeb (1981) and Kenny (1986) for important discussions of this point.) Locke rejects rationalism in the form of any version of the Innate Knowledge or Innate Concept theses, but he nonetheless adopts the Intuition/Deduction thesis with regard to our knowledge of God’s existence, in addition to our knowledge of mathematics and morality. Descartes and Locke have remarkably similar views on the nature of our ideas, even though Descartes takes many to be innate, while Locke ties them all to experience. The rationalist/empiricist classification also encourages us to expect the philosophers on each side of the divide to have common research programs in areas beyond epistemology. Thus, Descartes, Spinoza and Leibniz are mistakenly seen as applying a reason-centered epistemology to a common metaphysical agenda, with each trying to improve on the efforts of the one before, while Locke, Hume, and Reid are mistakenly seen as gradually rejecting those metaphysical claims, with each consciously trying to improve on the efforts of his predecessors. It is also important to note that the rationalist/empiricist distinction is not exhaustive of the possible sources of knowledge. One might claim, for example, that we can gain knowledge in a particular area by a form of Divine revelation or insight that is a product of neither reason nor sense experience. In short, when used carelessly, the labels ‘rationalist’ and ‘empiricist,’ as well as the slogan that is the title of this essay, ‘Rationalism vs. Empiricism,’ can impede rather than advance our understanding.

An important wrinkle for using this classification scheme in the history of philosophy is that it leaves out discussions of philosophical figures who did not focus their efforts on understanding whether innate knowledge is possible or even fruitful to have. Philosophy in the early modern period, in particular, is a lot richer than this artificial, simplifying distinction makes it sound. There is no clear way of grouping Hobbes with either camp, let alone Elizabeth of Bohemia, Anne Conway, George Berkeley, Émilie du Châtelet, or Mary Shepherd. This distinction, initially applied by Kant, is responsible for giving us a very restrictive philosophical canon, which does not take into account developments in the philosophy of emotions, philosophy of education, and even disputes in areas of philosophy considered more mainstream, like ethics and aesthetics.

Unless restricted to debates regarding the possibility of innate knowledge, this distinction is best left unused. The most interesting form of the debate occurs when we take the relevant subject to be truths about the external world, the world beyond our own minds. A full-fledged rationalist with regard to our knowledge of the external world holds that some external world truths are and must be innate and that this knowledge is superior to any that sense experience could ever provide. The full-fledged empiricist about our knowledge of the external world replies that, when it comes to the nature of the world beyond our own minds, experience is our sole source of information. Reason might inform us of the relations among our ideas, but those ideas themselves can only be gained, and any truths about the external reality they represent can only be known, on the basis of experience. This debate concerning our knowledge of the external world will generally be our main focus in what follows.

Historically, the rationalist/empiricist dispute in epistemology has extended into the area of metaphysics, where philosophers are concerned with the basic nature of reality, including the existence of God and such aspects of our nature as free-will and the relation between the mind and body. Several rationalists (e.g., Descartes, Meditations ) have presented metaphysical theories, which they have claimed to know by intuition and/or deduction alone. Empiricists (e.g., Hume, Treatise) have rejected the theories as either speculation, beyond what we can learn from experience, or nonsensical attempts to describe aspects of the world beyond the concepts experience can provide. The debate raises the issue of metaphysics as an area of knowledge. Kant puts the driving assumption clearly:

The very concept of metaphysics ensures that the sources of metaphysics can’t be empirical. If something could be known through the senses, that would automatically show that it doesn’t belong to metaphysics; that’s an upshot of the meaning of the word ‘metaphysics.’ Its basic principles can never be taken from experience, nor can its basic concepts; for it is not to be physical but metaphysical knowledge, so it must be beyond experience. ( Prolegomena , Preamble, I, p. 7)

The possibility then of metaphysics so understood, as an area of human knowledge, hinges on how we resolve the rationalist/empiricist debate. The debate also extends into ethics. Some moral objectivists (e.g., Ross 1930 and Huemer 2005) take us to know some fundamental objective moral truths by intuition, while some moral skeptics, who reject such knowledge (e.g., Mackie 1977), find the appeal to a faculty of moral intuition utterly implausible. More recently, the rationalist/empiricist debate has extended to discussions (e.g., Bealer 1999 and Alexander & Weinberg 2007) of the very nature of philosophical inquiry: to what extent are philosophical questions to be answered by appeals to reason or experience?

The Intuition/Deduction thesis claims that we can know some propositions by intuition and still more by deduction. Since traditionally this thesis was thought to be rejected by empiricists and adopted only by rationalists, it is useful to become more familiar with it. In a very narrow sense, only rationalists seem to adopt it. However, the current consensus is that most empiricists (e.g., Locke, Hume, Reid) have been willing to accept a version of the thesis, namely inasmuch as it is restricted to propositions solely about the relations among our own concepts. We can, they agree, know by intuition that our concept of God includes our concept of omniscience. Just by examining the concepts, we can intellectually grasp that the one includes the other. The debate between rationalists and empiricists is joined when the former assert, and the latter deny, the Intuition/Deduction thesis with regard to propositions that contain substantive information about the external world. Rationalists, such as Descartes, have claimed that we can know by intuition and deduction that God exists and created the world, that our mind and body are distinct substances, and that the angles of a triangle equal two right angles, where all of these claims are truths about an external reality independent of our thought. Such substantive versions of the Intuition/Deduction thesis are our concern in this section.

One defense of the Intuition/Deduction thesis assumes that we know some substantive external world truths, adds an analysis of what knowledge requires, and concludes that our knowledge must result from intuition and deduction. Rationalists and empiricists alike claim that certainty is required for scientia (which is a type of absolute knowledge of the necessary connections that would explain why certain things are a certain way) and that certainty about the external world is beyond what empirical evidence can provide. Empiricists seem happy to then conclude that the type of knowledge of the external world that we can acquire does not have this high degree of certainty and is, thus, not scientia . This is because we can never be sure our sensory impressions are not part of a dream or a massive, demon orchestrated, deception. A rationalist like Descartes of the Meditations , claims that only intuition can provide the certainty needed for such knowledge. This, after his arguing in the Rules that, when we “review all the actions of the intellect by means of which we are able to arrive at a knowledge of things with no fear of being mistaken,” we “recognize only two: intuition and deduction” ( Rules , Rule III, p. 3).

This line of argument is one of the least compelling in the rationalist arsenal. First, the assumption that knowledge requires certainty comes at a heavy cost, as it rules out so much of what we commonly take ourselves to know. Second, as many contemporary rationalists accept, intuition is not always a source of certain knowledge. The possibility of a deceiver gives us a reason to doubt our intuitions as well as our empirical beliefs. For all we know, a deceiver might cause us to intuit false propositions, just as one might cause us to have perceptions of nonexistent objects. Descartes’s classic way of meeting this challenge in the Meditations is to argue that we can know with certainty that no such deceiver interferes with our intuitions and deductions. They are infallible, as God guarantees their truth. The problem, known as the Cartesian Circle, is that Descartes’s account of how we gain this knowledge begs the question, by attempting to deduce the conclusion that all our intuitions are true from intuited premises. Moreover, his account does not touch a remaining problem that he himself notes ( Rules , Rule VII, p. 7): Deductions of any appreciable length rely on our fallible memory.

A more plausible argument for the Intuition/Deduction thesis again assumes that we know some particular, external world truths, and then appeals to the nature of what we know, rather than to the nature of knowledge itself, to argue that our knowledge must result from intuition and deduction. Leibniz, in New Essays , tells us the following:

The senses, although they are necessary for all our actual knowledge, are not sufficient to give us the whole of it, since the senses never give anything but instances, that is to say particular or individual truths. Now all the instances which confirm a general truth, however numerous they may be, are not sufficient to establish the universal necessity of this same truth, for it does not follow that what happened before will happen in the same way again. … From which it appears that necessary truths, such as we find in pure mathematics, and particularly in arithmetic and geometry, must have principles whose proof does not depend on instances, nor consequently on the testimony of the senses, although without the senses it would never have occurred to us to think of them… ( New Essays , Preface, pp. 150–151)

Leibniz goes on to describe our mathematical knowledge as “innate,” and his argument is more commonly directed to support the Innate Knowledge thesis rather than the Intuition/Deduction thesis. For our purposes here, we can relate it to the latter, however: We have substantive knowledge about the external world in mathematics, and what we know in that area, we know to be necessarily true. Experience cannot warrant beliefs about what is necessarily the case. Hence, experience cannot be the source of our knowledge. The best explanation of our knowledge is that we gain it by intuition and deduction. Leibniz mentions logic, metaphysics, and morals as other areas in which our knowledge similarly outstrips what experience can provide. Judgments in logic and metaphysics involve forms of necessity beyond what experience can support. Judgments in morals involve a form of obligation or value that lies beyond experience, which only informs us about what is the case rather than about what ought to be.

The strength of this argument varies with its examples of purported knowledge. Insofar as we focus on controversial claims in metaphysics, e.g., that God exists, that our mind is a distinct substance from our body, the initial premise that we know the claims is less than compelling. Taken with regard to other areas, however, the argument clearly has legs. We know a great deal of mathematics, and what we know, we know to be necessarily true. None of our experiences warrants a belief in such necessity, and we do not seem to base our knowledge on any experiences. The warrant that provides us with knowledge arises from an intellectual grasp of the propositions which is clearly part of our learning. Similarly, we seem to have such moral knowledge as that, all other things being equal, it is wrong to break a promise and that pleasure is intrinsically good. No empirical lesson about how things are can warrant such knowledge of how they ought to be.

This argument for the Intuition/Deduction thesis raises additional questions which rationalists must answer. Insofar as they maintain that our knowledge of necessary truths in mathematics or elsewhere by intuition and deduction is substantive knowledge of the external world, they owe us an account of this form of necessity. Many empiricists stand ready to argue that “necessity resides in the way we talk about things, not in the things we talk about” (Quine 1966, p. 174). Similarly, if rationalists claim that our knowledge in morals is knowledge of an objective form of obligation, they owe us an account of how objective values are part of a world of apparently valueless facts.

Perhaps most of all, any defenders of the Intuition/Deduction thesis owe us an account of what intuition is and how it provides warranted true beliefs about the external world. What is it to intuit a proposition and how does that act of intuition support a warranted belief? Their argument presents intuition and deduction as an explanation of assumed knowledge that can’t—they say—be explained by experience, but such an explanation by intuition and deduction requires that we have a clear understanding of intuition and how it supports warranted beliefs. Metaphorical characterizations of intuition as intellectual “grasping” or “seeing” are not enough, and if intuition is some form of intellectual “grasping,” it appears that all that is grasped is relations among our concepts, rather than facts about the external world, as the empiricists defenders of intuition and deduction argue. One current approach to the issue involves an appeal to Phenomenal Conservatism (Huemer 2001), the principle that if it seems to one as if something is the case, then one is prima facie justified in believing that it is so. Intuitions are then taken to be a particular sort of seeming or appearance: “[A]n intuition that p is a state of its seeming to one that p that is not dependent on inference from other beliefs and that results from thinking about p, as opposed to perceiving, remembering, or introspecting” (Huemer 2005, p. 102). Just as it can visually seem or appear to one as if there’s a tree outside the window, it can intellectually seem or appear to one as if nothing can be both entirely red and entirely green. This approach aims to demystify intuitions; they are but one more form of seeming-state along with ones we gain from sense perception, memory, and introspection. It does not, however, tell us all we need to know. Any intellectual faculty, whether it be sense perception, memory, introspection or intuition, provides us with warranted beliefs only if it is generally reliable. The reliability of sense perception stems from the causal connection between how external objects are and how we experience them. What accounts for the reliability of our intuitions regarding the external world? Is our intuition of a particular true proposition the outcome of some causal interaction between ourselves and some aspect of the world? What aspect? What is the nature of this causal interaction? That the number three is prime does not appear to cause anything, let alone our intuition that it is prime. As Michael Huemer (2005, p. 123) points out in mounting his own defense of moral intuitionism, “The challenge for the moral realist, then, is to explain how it would be anything more than chance if my moral beliefs were true, given that I do not interact with moral properties.”

These issues are made all the more pressing by the classic empiricist response to the argument. The reply is generally credited to Hume and begins with a division of all true propositions into two categories.

All the objects of human reason or inquiry may naturally be divided into two kinds, to wit, “Relations of Ideas,” and “Matters of Fact.” Of the first are the sciences of Geometry, Algebra, and Arithmetic, and, in short, every affirmation which is either intuitively or demonstratively certain. That the square of the hypotenuse is equal to the square of the two sides is a proposition which expresses a relation between these figures. That three times five is equal to half of thirty expresses a relation between these numbers. Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe. Though there never were a circle or triangle in nature, the truths demonstrated by Euclid would forever retain their certainty and evidence. Matters of fact, which are the second objects of human reason, are not ascertained in the same manner, nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible, because it can never imply a contradiction and is conceived by the mind with the same facility and distinctness as if ever so conformable to reality. ( Enquiry , 4.1, p. 24)

Intuition and deduction can provide us with knowledge of necessary truths such as those found in mathematics and logic, but such knowledge is not substantive knowledge of the external world. It is only knowledge of the relations of our own ideas. If the rationalist shifts the argument so it appeals to knowledge in morals, Hume’s reply is to offer an analysis of our moral concepts by which such knowledge is empirically gained knowledge of matters of fact.

Morals and criticism are not so properly objects of the understanding as of taste and sentiment. Beauty, whether moral or natural, is felt more properly than perceived. Or if we reason concerning it and endeavor to fix the standard, we regard a new fact, to wit, the general taste of mankind, or some other fact which may be the object of reasoning and inquiry. ( Enquiry , 12.3, p. 122)

If the rationalist appeals to our knowledge in metaphysics to support the argument, Hume denies that we have such knowledge.

If we take in our hand any volume--of divinity or school metaphysics, for instance--let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion. ( Enquiry , 12.3, p. 123)

An updated version of this general empiricist reply, with an increased emphasis on language and the nature of meaning, is given in the twentieth-century by A. J. Ayer’s version of logical positivism. Adopting positivism’s verification theory of meaning, Ayer assigns every cognitively meaningful sentence to one of two categories: either it is a tautology, and so true solely by virtue of the meaning of its terms and provides no substantive information about the world, or it is open to empirical verification. There is, then, no room for knowledge about the external world by intuition or deduction.

There can be no a priori knowledge of reality. For … the truths of pure reason, the propositions which we know to be valid independently of all experience, are so only in virtue of their lack of factual content … [By contrast] empirical propositions are one and all hypotheses which may be confirmed or discredited in actual sense experience. (Ayer 1952, pp. 86; 93–94)

The rationalists’ argument for the Intuition/Deduction thesis goes wrong at the start, according to empiricists, by assuming that we can have substantive knowledge of the external world that outstrips what experience can warrant. We cannot.

This empiricist reply faces challenges of its own. Our knowledge of mathematics seems to be about something more than our own concepts. Our knowledge of moral judgments seems to concern not just how we feel or act but how we ought to behave. The general principles that provide a basis for the empiricist view, e.g. Hume’s overall account of our ideas, the Verification Principle of Meaning, are problematic in their own right.

In all, rationalists have an argument for the Intuition/Deduction thesis relative to our substantive knowledge of the external world, but its success rests on how well they can answer questions about the nature and epistemic force of intuition made all the more pressing by the classic empiricist reply.

The Innate Knowledge thesis asserts that we have a priori knowledge, that is knowledge independent, for its justification, of sense experience, as part of our rational nature. Experience may trigger our awareness of this knowledge, but it does not provide us with it. The knowledge is already there.

Plato presents an early version of the Innate Knowledge thesis in the Meno as the doctrine of knowledge by recollection. The doctrine is motivated in part by a paradox that arises when we attempt to explain the nature of inquiry. How do we gain knowledge of a theorem in geometry? We inquire into the matter. Yet, knowledge by inquiry seems impossible ( Meno , 80d-e). We either already know the theorem at the start of our investigation or we do not. If we already have the knowledge, there is no place for inquiry. If we lack the knowledge, we don’t know what we are seeking and cannot recognize it when we find it. Either way we cannot gain knowledge of the theorem by inquiry. Yet, we do know some theorems.

The doctrine of knowledge by recollection offers a solution. When we inquire into the truth of a theorem, we both do and do not already know it. We have knowledge in the form of a memory gained from our soul’s knowledge of the theorem prior to its union with our body. We also lack some knowledge because, in our soul’s unification with the body, it has forgotten the knowledge and now needs to recollect it. Thus, learning the theorem allows us, in effect, to recall what we already know.

Plato famously illustrates the doctrine with an exchange between Socrates and a young slave, in which Socrates guides the slave from ignorance to mathematical knowledge. The slave’s experiences, in the form of Socrates’ questions and illustrations, are the occasion for his recollection of what he learned previously. Plato’s metaphysics provides additional support for the Innate Knowledge Thesis. Since our knowledge is of abstract, eternal Forms, which clearly lie beyond our sensory experience, it is independent, for its justification, of experience.

Contemporary supporters of Plato’s position are scarce. The initial paradox, which Plato describes as a “trick argument” ( Meno , 80e), rings sophistical. The metaphysical assumptions in the solution need justification. The solution does not answer the basic question: Just how did the slave’s soul learn the theorem? The Intuition/Deduction thesis offers an equally, if not more, plausible account of how the slave gains this type of knowledge that is independent of experience. Nonetheless, Plato’s position illustrates the kind of reasoning that has caused many philosophers to adopt some form of the Innate Knowledge thesis. We are confident that we know certain propositions about the external world, but there seems to be no adequate explanation of how we gained this knowledge short of saying that it is innate. Its content is beyond what we directly gain in experience, as well as what we can gain by performing mental operations on what experience provides. It does not seem to be based on an intuition or deduction. That it is innate in us appears to be the best explanation.

Noam Chomsky argues along similar lines in presenting what he describes as a “rationalist conception of the nature of language” (1975, p. 129). Chomsky argues that the experiences available to language learners are far too sparse to account for their knowledge of their language. To explain language acquisition, we must assume that learners have an innate knowledge of a universal grammar capturing the common deep structure of natural languages. It is important to note that Chomsky’s language learners do not know particular propositions describing a universal grammar. They have a set of innate capacities or dispositions which enable and determine their language development. Chomsky gives us a theory of innate learning capacities or structures rather than a theory of innate knowledge. His view does not support the Innate Knowledge thesis as rationalists have traditionally understood it. As one commentator puts it, “Chomsky’s principles … are innate neither in the sense that we are explicitly aware of them, nor in the sense that we have a disposition to recognize their truth as obvious under appropriate circumstances. And hence it is by no means clear that Chomsky is correct in seeing his theory as following the traditional rationalist account of the acquisition of knowledge” (Cottingham 1984, p. 124). Indeed, such a theory, which places nativism at the level of mental capacities or structures enabling us to acquire certain types of knowledge rather than at the level of knowledge we already posses, is akin to an empiricist take on the issue. Locke and Reid, for instance, believe that the human mind is endowed with certain abilities that, when developed in the usual course of nature, will lead us to acquire useful knowledge of the external world. The main idea is that it is part of our biology to have a digestive system that, when fed the right kind of food, allows us to process the required nutrients to enable us to continue to live for a while. Similarly, it is part of our biology to have a mental architecture that, when fed the right kind of information and experiences, allows us to process that information and transform it into knowledge. The knowledge itself is no more innate than the processed nutrients are. On a view like this, no knowledge is innate; however, we are born with certain capabilities and disposition that enable us to acquire knowledge, just as we are equipped with certain organs that allow our bodies to function well while we’re alive.

Peter Carruthers (1992) argues that we have innate knowledge of the principles of folk-psychology. Folk-psychology is a network of common-sense generalizations that hold independently of context or culture and concern the relationships of mental states to one another, to the environment and states of the body and to behavior (1992, p. 115). It includes such beliefs as that pains tend to be caused by injury, that pains tend to prevent us from concentrating on tasks, and that perceptions are generally caused by the appropriate state of the environment. Carruthers notes the complexity of folk-psychology, along with its success in explaining our behavior and the fact that its explanations appeal to such unobservables as beliefs, desires, feelings, and thoughts. He argues that the complexity, universality, and depth of folk-psychological principles outstrips what experience can provide, especially to young children who by their fifth year already know a great many of them. This knowledge is also not the result of intuition or deduction; folk-psychological generalizations are not seen to be true in an act of intellectual insight. Carruthers concludes, “[The problem] concerning the child’s acquisition of psychological generalizations cannot be solved, unless we suppose that much of folk-psychology is already innate, triggered locally by the child’s experience of itself and others, rather than learned” (1992, p. 121).

Empiricists, and some rationalists, attack the Innate Knowledge thesis in two main ways. First, they offer accounts of how sense experience or intuition and deduction provide the knowledge that is claimed to be innate. Second, they directly criticize the Innate Knowledge thesis itself. The classic statement of this second line of attack is presented in Locke’s Essay . Locke raises the issue of just what innate knowledge is. Particular instances of knowledge are supposed to be in our minds as part of our rational make-up, but how are they “in our minds”? If the implication is that we all consciously have this knowledge, it is plainly false. Propositions often given as examples of innate knowledge, even such plausible candidates as the principle that the same thing cannot both be and not be, are not consciously accepted by children and those with severe cognitive limitations. If the point of calling such principles “innate” is not to imply that they are or have been consciously accepted by all rational beings, then it is hard to see what the point is. “No proposition can be said to be in the mind, which it never yet knew, which it never yet was conscious of” ( Essay , 1.2.5). Proponents of innate knowledge might respond that some knowledge is innate in that we have the capacity to have it. That claim, while true, is of little interest, however. “If the capacity of knowing, be the natural impression contended for, all the truths a man ever comes to know, will, by this account, be every one of them, innate; and this great point will amount to no more, but only an improper way of speaking; which whilst it pretends to assert the contrary, says nothing different from those, who deny innate principles. For nobody, I think, ever denied, that the mind was capable of knowing several truths” ( Essay , 1.2.5). Locke thus challenges defenders of the Innate Knowledge thesis to present an account of innate knowledge that allows their position to be both true and interesting. A narrow interpretation of innateness faces counterexamples of rational individuals who do not meet its conditions. A generous interpretation implies that all our knowledge, even that clearly provided by experience, is innate.

Defenders of innate knowledge take up Locke’s challenge. Leibniz responds in New Essays by appealing to an account of innateness in terms of natural potential to avoid Locke’s dilemma. Consider Peter Carruthers’ similar reply.

We have noted that while one form of nativism claims (somewhat implausibly) that knowledge is innate in the sense of being present as such (or at least in propositional form) from birth, it might also be maintained that knowledge is innate in the sense of being innately determined to make its appearance at some stage in childhood. This latter thesis is surely the most plausible version of nativism. (1992, p. 51)

Carruthers claims that our innate knowledge is determined through evolutionary selection (p. 111). Evolution has resulted in our being determined to know certain things (e.g. principles of folk-psychology) at particular stages of our life, as part of our natural development. Experiences provide the occasion for our consciously believing the known propositions but not the basis for our knowledge of them (p. 52). Carruthers thus has a ready reply to Locke’s counterexamples of children and cognitively limited persons who do not believe propositions claimed to be instances of innate knowledge. The former have not yet reached the proper stage of development; the latter are persons in whom natural development has broken down (pp. 49–50).

A serious problem for the Innate Knowledge thesis remains, however. We know a proposition only if it is true, we believe it and our belief is warranted. Rationalists who assert the existence of innate knowledge are not just claiming that, as a matter of human evolution, God’s design or some other factor, at a particular point in our development, certain sorts of experiences trigger our belief in particular propositions in a way that does not involve our learning them from the experiences. Their claim is even bolder: In at least some of these cases, our empirically triggered, but not empirically warranted, belief is nonetheless warranted and so known. How can these beliefs be warranted if they do not gain their warrant from the experiences that cause us to have them or from intuition and deduction?

Some rationalists think that a reliabilist account of warrant provides the answer. According to Reliabilism, beliefs are warranted if they are formed by a process that generally produces true beliefs rather than false ones. The true beliefs that constitute our innate knowledge are warranted, then, because they are formed as the result of a reliable belief-forming process. Carruthers maintains that “Innate beliefs will count as known provided that the process through which they come to be innate is a reliable one (provided, that is, that the process tends to generate beliefs that are true)” (1992, p. 77). He argues that natural selection results in the formation of some beliefs and is a truth-reliable process.

An appeal to Reliabilism, or a similar causal theory of warrant, may well be the best way to develop the Innate Knowledge thesis. Even so, some difficulties remain. First, reliabilist accounts of warrant are themselves quite controversial. Second, rationalists must give an account of innate knowledge that maintains and explains the distinction between innate knowledge and non-innate knowledge, and it is not clear that they will be able to do so within such an account of warrant. Suppose for the sake of argument that we have innate knowledge of some proposition, P . What makes our knowledge that P innate? To sharpen the question, what difference between our knowledge that P and a clear case of non-innate knowledge, say our knowledge that something is red based on our current visual experience of a red table, makes the former innate and the latter not innate? In each case, we have a true, warranted belief. In each case, presumably, our belief gains its warrant from the fact that it meets a particular causal condition, e.g., it is produced by a reliable process. In each case, the causal process is one in which an experience causes us to believe the proposition at hand (that P ; that something is red), for, as defenders of innate knowledge admit, our belief that P is “triggered” by an experience, as is our belief that something is red. The insight behind the Innate Knowledge thesis seems to be that the difference between our innate and non-innate knowledge lies in the relation between our experience and our belief in each case. The experience that causes our belief that P does not “contain” the information that P , while our visual experience of a red table does “contain” the information that something is red. Yet, exactly what is the nature of this containment relation between our experiences, on the one hand, and what we believe, on the other, that is missing in the one case but present in the other? The nature of the experience-belief relation seems quite similar in each. The causal relation between the experience that triggers our belief that P and our belief that P is contingent, as is the fact that the belief-forming process is reliable. The same is true of our experience of a red table and our belief that something is red. The causal relation between the experience and our belief is again contingent. We might have been so constructed that the experience we describe as “being appeared to redly” caused us to believe, not that something is red, but that something is hot. The process that takes us from the experience to our belief is also only contingently reliable. Moreover, if our experience of a red table “contains” the information that something is red, then that fact, not the existence of a reliable belief-forming process between the two, should be the reason why the experience warrants our belief. By appealing to Reliabilism, or some other causal theory of warrant, rationalists may obtain a way to explain how innate knowledge can be warranted. They still need to show how their explanation supports an account of the difference between innate knowledge and non-innate knowledge. So, Locke's criticism -- that there is no true distinction between innate versus non-innate knowledge that rationalists may draw -- still stands, in the face of the best rationalist defense of the Innate Knowledge thesis.

According to the Innate Concept thesis, some of our concepts have not been gained from experience. They are instead part of our rational make-up, and experience simply triggers a process by which we consciously grasp them. The main concern motivating the rationalist should be familiar by now: the content of some concepts seems to outstrip anything we could have gained from experience. An example of this reasoning is presented by Descartes in the Meditations . Although he sometimes seems committed to the view that all our ideas are innate (Adams 1975 and Gotham 2002), he there classifies our ideas as adventitious, invented by us, and innate. Adventitious ideas, such as a sensation of heat, are gained directly through sense experience. Ideas invented by us, such as our idea of a hippogriff, are created by us from other ideas we possess. Innate ideas, such as our ideas of God, of extended matter, of substance, and of a perfect triangle, are placed in our minds by God at creation. Consider Descartes’s argument that our concept of God, as an infinitely perfect being, is innate. Our concept of God is not directly gained in experience, as particular tastes, sensations, and mental images might be. Its content is beyond what we could ever construct by applying available mental operations to what experience directly provides. From experience, we can gain the concept of a being with finite amounts of various perfections, one, for example, that is finitely knowledgeable, powerful and good. We cannot however move from these empirical concepts to the concept of a being of infinite perfection. (“I must not think that, just as my conceptions of rest and darkness are arrived at by negating movement and light, so my perception of the infinite is arrived at not by means of a true idea but by merely negating the finite,” Third Meditation, p. 94.) Descartes supplements this argument by another. Not only is the content of our concept of God beyond what experience can provide, the concept is a prerequisite for our employment of the concept of finite perfection gained from experience. (“My perception of the infinite, that is God, is in some way prior to my perception of the finite, that is myself. For how could I understand that I doubted or desired—that is lacked something—and that I was not wholly perfect, unless there were in me some idea of a more perfect being which enabled me to recognize my own defects by comparison,” Third Meditation, p. 94).

An empiricist response to this general line of argument is given by Locke ( Essay , 1.4.1–25). First, there is the problem of explaining what it is for someone to have an innate concept. If having an innate concept entails consciously entertaining it at present or in the past, then Descartes’s position is open to obvious counterexamples. Young children and people from other cultures do not consciously entertain the concept of God and have not done so. Second, there is the objection that we have no need to appeal to innate concepts in the first place. Contrary to Descartes’s argument, we can explain how experience provides all our ideas, including those the rationalists take to be innate, and with just the content that the rationalists attribute to them.

Leibniz’s New Essays offers a rationalist reply to the first concern. Where Locke puts forth the image of the mind as a blank slate on which experience writes, Leibniz offers us the image of a block of marble, the veins of which determine what sculpted figures it will accept ( New Essays , Preface, p. 153). Leibniz’s metaphor contains an insight that Locke misses. The mind plays a role in determining the nature of its contents. This point does not, however, require the adoption of the Innate Concept thesis. Locke might still point out that we are not required to have the concepts themselves and the ability to use them, innately. In contemporary terms, what we are required to have is the right hardware that allows for the optimal running of the actual software. For Locke, there are no constrains here; for Leibniz, only a particular type of software is, indeed, able to be supported by the extant hardware. Put differently, the hardware itself determines what software can be optimally run, for a Leibnizian.

Rationalists have responded to the second part of the empiricist attack on the Innate Concept thesis—the empiricists’ claim that the thesis is without basis, as all our ideas can be explained as derived from experience—by focusing on difficulties in the empiricists’ attempts to give such an explanation. The difficulties are illustrated by Locke’s account. According to Locke, experience consists in external sensation and inner reflection. All our ideas are either simple or complex, with the former being received by us passively in sensation or reflection and the latter being built by the mind from simple materials through various mental operations. Right at the start, the account of how simple ideas are gained is open to an obvious counterexample acknowledged, but then set aside, by Hume in presenting his own empiricist theory. Consider the mental image of a particular shade of blue. If Locke is right, the idea is a simple one and should be passively received by the mind through experience. Hume points out otherwise:

Suppose therefore a person to have enjoyed his sight for thirty years and to have become perfectly acquainted with colors of all kinds, except one particular shade of blue, for instance, which it never has been his fortune to meet with; let all the different shades of that color, except that single one, be placed before him, descending gradually from the deepest to the lightest, it is plain that he will perceive a blank where that shade is wanting and will be sensible that there is a greater distance in that place between the contiguous colors than in any other. Now I ask whether it be possible for him, from his own imagination, to supply this deficiency and raise up to himself the idea of that particular shade, though it had never been conveyed to him by his senses? I believe there are but few will be of the opinion that he can… ( Enquiry , 2, pp. 15–16)

Even when it comes to such simple ideas as the image of a particular shade of blue, the mind seems to be more than a blank slate on which experience writes. The main question is whether the veins in Leibniz’s metaphor should count as part of the knowledge or just as part of our biological mental architecture: all the knowledge we can ever acquire is constrained by the type of beings we are. This does not require our positing that concepts be part of the inner workings, at the beginning of our lives.

On the other hand, consider, too, our concept of a particular color, say red. Critics of Locke’s account have pointed out the weaknesses in his explanation of how we gain such a concept by the mental operation of abstraction on individual cases. For one thing, it makes the incorrect assumption that various instances of a particular concept share a common feature. Carruthers puts the objection as follows:

In fact problems arise for empiricists even in connection with the very simplest concepts, such as those of colour. For it is false that all instances of a given colour share some common feature. In which case we cannot acquire the concept of that colour by abstracting the common feature of our experience. Thus consider the concept red . Do all shades of red have something in common? If so, what? It is surely false that individual shades of red consist, as it were, of two distinguishable elements a general redness together with a particular shade. Rather, redness consists in a continuous range of shades, each of which is only just distinguishable from its neighbors. Acquiring the concept red is a matter of learning the extent of the range. (1992, p. 59)

For another thing, Locke’s account of concept acquisition from particular experiences seems circular: “For noticing or attending to a common feature of various things presupposes that you already possess the concept of the feature in question.” (Carruthers 1992, p. 55)

Consider in this regard Locke’s account of how we gain our concept of causation.

In the notice that our senses take of the constant vicissitude of things, we cannot but observe, that several particulars, both qualities and substances; begin to exist; and that they receive this their existence from the due application and operation of some other being. From this observation, we get our ideas of cause and effect. ( Essay , 2.26.1)

We get our concept of causation from our observation that some things receive their existence from the application and operation of some other things. Yet, to be able to make this observation, we must have our minds primed to do so. Rationalists argue that we cannot make this observation unless we already have the concept of causation. Empiricists, on the other hand, argue that our minds are constituted in a certain way, so that we can gain our ideas of causation and of power in a non-circular manner.

Rationalists would argue that Locke’s account of how we gain our idea of power displays a similar circularity.

The mind being every day informed, by the senses, of the alteration of those simple ideas, it observes in things without; and taking notice how one comes to an end, and ceases to be, and another begins to exist which was not before; reflecting also on what passes within itself, and observing a constant change of its ideas, sometimes by the impression of outward objects on the senses, and sometimes by the determination of its own choice; and concluding from what it has so constantly observed to have been, that the like changes will for the future be made in the same things, by like agents, and by the like ways, considers in one thing the possibility of having any of its simple ideas changed, and in another the possibility of making that change; and so comes by that idea which we call power. ( Essay , 2.21.1)

We come by the idea of power though considering the possibility of changes in our ideas made by experiences and our own choices. Yet, to consider this possibility—of some things making a change in others—we must already have a concept of power, rationalists would say. Empiricists, on the other hand, would point out, again, that what we actually need is for our minds to be able to recognize this, by having the correct abilities and faculties. Just as we don’t need to have a concept telling us how it is that we have binocular vision, being able to recognize change would be cashed out by us having the requisite faculty enabling us to do so.

Another way to meet at least some of these challenges to an empiricist account of the origin of our concepts is to revise our understanding of the content of our concepts so as to bring them more in line with what experience will clearly provide. Hume famously takes this approach. Beginning in a way reminiscent of Locke, he distinguishes between two forms of mental contents or “perceptions,” as he calls them: impressions and ideas. Impressions are the contents of our current experiences: our sensations, feelings, emotions, desires, and so on. Ideas are mental contents derived from impressions. Simple ideas are copies of impressions; complex ideas are derived from impressions by “compounding, transposing, augmenting or diminishing” them. Given that all our ideas are thus gained from experience, Hume offers us the following method for determining the content of any idea and thereby the meaning of any term taken to express it.

When we entertain, therefore, any suspicion that a philosophical term is employed without any meaning or idea (as is but too frequent), we need but inquire from what impression is that supposed idea derived ? And if it be impossible to assign any, this will confirm our suspicion. ( Enquiry , 2, p. 16)

Using this test, Hume draws out one of the most important implications of the empiricists’ denial of the Innate Concept thesis. If experience is indeed the source of all ideas, then our experiences also determine the content of our ideas. Our ideas of causation, of substance, of right and wrong have their content determined by the experiences that provide them. Those experiences, Hume argues, are unable to support the content that many rationalists and some empiricists, such as Locke, attribute to the corresponding ideas. Our inability to explain how some concepts, with the contents the rationalists attribute to them, are gained from experience should not lead us to adopt the Innate Concept thesis. It should lead us to accept a more limited view of the contents for those concepts, and thereby a more limited view of our ability to describe and understand the world.

Consider, for example, our idea of causation. Descartes takes it to be innate. Hume’s empiricist account severely limits its content. Our idea of causation is derived from a feeling of expectation rooted in our experiences of the constant conjunction of similar causes and effects.

It appears, then, that this idea of a necessary connection among events arises from a number of similar instances which occur, of the constant conjunction of these events; nor can that idea ever be suggested by any one of these instances surveyed in all possible lights and positions. But there is nothing in a number of instances, different from every single instance, which is supposed to be exactly similar, except only that after a repetition of similar instances the mind is carried by habit, upon the appearance of one event, to expect its usual attendant and to believe that it will exist. This connection, therefore, which we feel in the mind, this customary transition of the imagination from one object to its usual attendant, is the sentiment or impression from which we form the idea of power or necessary connection. ( Enquiry , 7.2, p. 59)

The source of our idea in experience determines its content.

Suitably to this experience, therefore, we may define a cause to be an object followed by another, and where all the objects, similar to the first are followed by objects similar to the second… We may, therefore, suitably to this experience, form another definition of cause and call it an object followed by another, and whose appearance always conveys the thought of the other . ( Enquiry , 7.2, p. 60)

Our claims, and any knowledge we may have, about causal connections in the world turn out, given the limited content of our empirically based concept of causation, to be claims and knowledge about the constant conjunction of events and our own feelings of expectation. Thus, the initial disagreement between rationalists and empiricists about the source of our ideas leads to one about their content and thereby the content of our descriptions and knowledge of the world.

Like philosophical debates generally, the rationalist/empiricist debate ultimately concerns our position in the world, in this case our position as rational inquirers. To what extent do our faculties of reason and experience support our attempts to know and understand our situation?

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What is Empirical Evidence?

Published Jan 5, 2018

Empirical evidence is information that researchers generate to help uncover answers to questions that can have significant implications for our society.

Take seatbelts. Prior to their invention, people were killed or maimed in what today we would think of as minor traffic accidents. So smart engineers put their heads together to try to do something about it.

Let’s try tying people down! Let’s change what the steering wheel is made of! Let’s put an exploding bag of air in the steering wheel! (Imagine how crazy that sounded in a pitch meeting.) These all seem like reasonable ideas (well except that exploding airbag one), so how do we know which one we should do?

The answer is to generate and weigh empirical evidence.

Theory vs. Empirical Evidence

One might have a theory about how something will play out, but what one observes or experiences can be different from what a theory might predict. People want to know the effectiveness of all sorts of things, which means they have to test them.

Social scientists produce empirical evidence in a variety of ways to test theories and measure the ability of A to produce an expected result: B.

Usually, researchers collect data through direct or indirect observation, and they analyze these data to answer empirical questions (questions that can be answered through observation).

Let’s look at our car safety example. Engineers and scientists equipped cars with various safety devices in various configurations, then smashed them into walls, poles and other cars and recorded what happened. Over time, they were able to figure out what types of safety devices worked and which ones didn’t. As it turns out, that whole airbag thing wasn’t so crazy after all.

They didn’t get everything right immediately. For instance, early seatbelts weren’t retractable. Some airbags shot pieces of metal into passengers . But, in fits and in starts, auto safety got better, and even though people are driving more and more miles, fewer and fewer are dying on the road .

How Gathering Empirical Evidence in Social Science is Different

Testing the effects of, say, a public policy on a group of people puts us in the territory of social science.

For instance, education research is not the same as automotive research because children (people) aren’t cars (objects). Education, though, can be made better by attempting new things, gathering data on those efforts, rigorously analyzing that data and then weighing all available empirical evidence to see if those new things accomplish what we hope they do.

Unfortunately, the “rigorously analyzing” bit is often missing from education research. In the labs of automobile engineers, great care is taken to only change one bit of design (a variable) at a time so that each test isolates the individual factor that is making a car more or less safe. OK, for this test, let’s just change the material of the steering wheel and keep everything else the same, so we’ll know if it is the wheel that is hurting people.

Comparing Apples with Apples

In social science and especially in education, trying to isolate variables is challenging, but possible, if researchers can make “apples-to-apples” comparisons.

The best way to get an apples-to-apples comparison is to perform something called a randomized control trial (RCT). You might have heard about these in relation to the testing of medicine. Drug testing uses RCTs all the time.

In an educational RCT, students are divided into two groups by a randomized lottery and half of the students receive whatever the educational “treatment” is (a new reading program, a change in approach to discipline, a school voucher, etc.) while the other does not. Researchers compare the results of those two groups and estimate the “treatment” effect. This approach gives us confidence that the observed effect is caused by the intervention and no other factors.

RCTs are not always possible. Sometimes researchers can get close by using random events that separate kids into two groups, such as school district boundaries that are created by rivers or creeks that split a community more or less by chance or birthday cutoffs for preschool that place a child born on August 31st in one grade but one born September 1st in another even though there is basically no difference between them. Depending on the exact nature of the event, these can be known as “regression discontinuity” or “instrumental variable” analyses, and they can be useful tools to estimate the effects of a program.

Researchers can also follow individual children that receive a treatment if they have data from before and after to see how that child’s educational trajectory changes over time. These are known as “fixed effects” analyses.

All three of these—randomized control trials, regression discontinuity analyses and fixed effects analyses —have their drawbacks.

Very few outside events are truly random. If, as regression discontinuity analysis often does, researchers only look at children just above or just below the cutoff, or, as fixed effects analysis often does, researchers look at only those children who switch from one school to another, those children might not be representative of the population. How would an intervention affect kids who are not close to a cutoff or border? Or kids who do not switch schools?

In the SlideShare below, we present empirical evidence based on rigorous research on private school choice programs as an example of how we, as academics and researchers ourselves, identify and characterize the high-quality empirical evidence in a given area of study.

[Slideshare no longer available]

A Couple Considerations

It’s a lot to wade through, so before you do, we’d like to offer two notes.

First, it is always important to understand the tradeoffs between internal and external validity.

Internal validity refers to how well a study is conducted—it gives us confidence that the effects we observe can be attributed to the intervention or program, not other factors.

For example, when the federal government wanted to know if Washington, D.C.’s school voucher program increased students’ reading and math test scores, researchers took the 2,308 students who applied for the program and randomly assigned 1,387 to get vouchers and 921 not to . They then followed the two groups over time, and when they analyzed the results, they could reasonably conclude that any differences were due to the offer of a voucher, because that is the only thing that was different between the two groups and they were different only because of random chance. This study had high internal validity.

External validity refers to the extent that we can generalize the findings from a study to other settings.

Let’s think about that same study. The D.C. program was unique. The amount of money that students receive, the regulations that participating schools had to agree to, the size of the program, its politically precarious situation and numerous other factors were different in that program than in others, not to mention the fact that Washington, D.C. is not representative of the United States as a whole demographically, politically or in really any way we can possibly imagine. As a result, we have to be cautious when we try to generalize the findings. The study has lower external validity.

To combat issues around lower external validity, researchers can collect and analyze empirical evidence on program design to understand its impact. We can also look at multiple studies to see how similar interventions affect students in different settings.

Second, the respect and use of research does not endorse technocracy. Research and expertise is incredibly useful. When you get on an airplane or head into surgery, you want the person who is doing the work to be an expert. Empirical evidence can help us know more about the world and be better at what we do. But we should also exercise restraint and humility by recognizing the limits of social science.

Public policy involves weighing tradeoffs that social science cannot do for us. Social science can tell us that a program increases reading scores but also increases anxiety and depression in children. Should that program be allowed to continue? Ultimately, that comes down to human judgment and values. That should never be forgotten.

With that, we hope you found this article helpful. Please feel free to reach out with any questions by emailing [email protected] or posting your question in the comments section below.

Michael Q. McShane

Director of National Research, EdChoice

Dr. Michael McShane is Director of National Research at EdChoice. He is the author, editor, co-author, or co-editor eleven books on education policy, including his most recent Hybrid Homeschooling: A Guide to the Future of Education (Rowman and Littlefield, 2021) He is currently an opinion contributor to Forbes, and his analyses and commentary have been published widely in the media, including in USA Today, The Washington Post, and the Wall Street Journal. He has also been featured in education-specific outlets such as Teachers College Record, Education Week, Phi Delta Kappan, and Education Next. In addition to authoring numerous white papers, McShane has had academic work published in Education Finance and Policy, The Handbook of Education Politics and Policy, and the Journal of School Choice. A former high school teacher, he earned a Ph.D. in education policy from the University of Arkansas, an M.Ed. from the University of Notre Dame, and a B.A. in English from St. Louis University.

Will Flanders

Education research director, wisconsin institute for law & liberty.

Will Flanders is the education research director at the Wisconsin Institute for Law & Liberty. He holds a Ph.D. in Political Science with a specialization in American Politics and Public Policy, an M.S. in Political Science and an M.S. in Applied American Politics and Policy from Florida State University.

New Polling Shows Parental Support for School Choice Policies Remains Strong in 2024

Colyn Ritter

Updated April 10, 2024

Parents Aren’t As Polarized As Some Assume, New Polling Report Shows

Updated April 9, 2024

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Solar Eclipse 2024

What the World Has Learned From Past Eclipses

C louds scudded over the small volcanic island of Principe, off the western coast of Africa, on the afternoon of May 29, 1919. Arthur Eddington, director of the Cambridge Observatory in the U.K., waited for the Sun to emerge. The remains of a morning thunderstorm could ruin everything.

The island was about to experience the rare and overwhelming sight of a total solar eclipse. For six minutes, the longest eclipse since 1416, the Moon would completely block the face of the Sun, pulling a curtain of darkness over a thin stripe of Earth. Eddington traveled into the eclipse path to try and prove one of the most consequential ideas of his age: Albert Einstein’s new theory of general relativity.

Eddington, a physicist, was one of the few people at the time who understood the theory, which Einstein proposed in 1915. But many other scientists were stymied by the bizarre idea that gravity is not a mutual attraction, but a warping of spacetime. Light itself would be subject to this warping, too. So an eclipse would be the best way to prove whether the theory was true, because with the Sun’s light blocked by the Moon, astronomers would be able to see whether the Sun’s gravity bent the light of distant stars behind it.

Two teams of astronomers boarded ships steaming from Liverpool, England, in March 1919 to watch the eclipse and take the measure of the stars. Eddington and his team went to Principe, and another team led by Frank Dyson of the Greenwich Observatory went to Sobral, Brazil.

Totality, the complete obscuration of the Sun, would be at 2:13 local time in Principe. Moments before the Moon slid in front of the Sun, the clouds finally began breaking up. For a moment, it was totally clear. Eddington and his group hastily captured images of a star cluster found near the Sun that day, called the Hyades, found in the constellation of Taurus. The astronomers were using the best astronomical technology of the time, photographic plates, which are large exposures taken on glass instead of film. Stars appeared on seven of the plates, and solar “prominences,” filaments of gas streaming from the Sun, appeared on others.

Eddington wanted to stay in Principe to measure the Hyades when there was no eclipse, but a ship workers’ strike made him leave early. Later, Eddington and Dyson both compared the glass plates taken during the eclipse to other glass plates captured of the Hyades in a different part of the sky, when there was no eclipse. On the images from Eddington’s and Dyson’s expeditions, the stars were not aligned. The 40-year-old Einstein was right.

“Lights All Askew In the Heavens,” the New York Times proclaimed when the scientific papers were published. The eclipse was the key to the discovery—as so many solar eclipses before and since have illuminated new findings about our universe.

Telescope used to observe a total solar eclipse, Sobral, Brazil, 1919.

To understand why Eddington and Dyson traveled such distances to watch the eclipse, we need to talk about gravity.

Since at least the days of Isaac Newton, who wrote in 1687, scientists thought gravity was a simple force of mutual attraction. Newton proposed that every object in the universe attracts every other object in the universe, and that the strength of this attraction is related to the size of the objects and the distances among them. This is mostly true, actually, but it’s a little more nuanced than that.

On much larger scales, like among black holes or galaxy clusters, Newtonian gravity falls short. It also can’t accurately account for the movement of large objects that are close together, such as how the orbit of Mercury is affected by its proximity the Sun.

Albert Einstein’s most consequential breakthrough solved these problems. General relativity holds that gravity is not really an invisible force of mutual attraction, but a distortion. Rather than some kind of mutual tug-of-war, large objects like the Sun and other stars respond relative to each other because the space they are in has been altered. Their mass is so great that they bend the fabric of space and time around themselves.

Read More: 10 Surprising Facts About the 2024 Solar Eclipse

This was a weird concept, and many scientists thought Einstein’s ideas and equations were ridiculous. But others thought it sounded reasonable. Einstein and others knew that if the theory was correct, and the fabric of reality is bending around large objects, then light itself would have to follow that bend. The light of a star in the great distance, for instance, would seem to curve around a large object in front of it, nearer to us—like our Sun. But normally, it’s impossible to study stars behind the Sun to measure this effect. Enter an eclipse.

Einstein’s theory gives an equation for how much the Sun’s gravity would displace the images of background stars. Newton’s theory predicts only half that amount of displacement.

Eddington and Dyson measured the Hyades cluster because it contains many stars; the more stars to distort, the better the comparison. Both teams of scientists encountered strange political and natural obstacles in making the discovery, which are chronicled beautifully in the book No Shadow of a Doubt: The 1919 Eclipse That Confirmed Einstein's Theory of Relativity , by the physicist Daniel Kennefick. But the confirmation of Einstein’s ideas was worth it. Eddington said as much in a letter to his mother: “The one good plate that I measured gave a result agreeing with Einstein,” he wrote , “and I think I have got a little confirmation from a second plate.”

The Eddington-Dyson experiments were hardly the first time scientists used eclipses to make profound new discoveries. The idea dates to the beginnings of human civilization.

Careful records of lunar and solar eclipses are one of the greatest legacies of ancient Babylon. Astronomers—or astrologers, really, but the goal was the same—were able to predict both lunar and solar eclipses with impressive accuracy. They worked out what we now call the Saros Cycle, a repeating period of 18 years, 11 days, and 8 hours in which eclipses appear to repeat. One Saros cycle is equal to 223 synodic months, which is the time it takes the Moon to return to the same phase as seen from Earth. They also figured out, though may not have understood it completely, the geometry that enables eclipses to happen.

The path we trace around the Sun is called the ecliptic. Our planet’s axis is tilted with respect to the ecliptic plane, which is why we have seasons, and why the other celestial bodies seem to cross the same general path in our sky.

As the Moon goes around Earth, it, too, crosses the plane of the ecliptic twice in a year. The ascending node is where the Moon moves into the northern ecliptic. The descending node is where the Moon enters the southern ecliptic. When the Moon crosses a node, a total solar eclipse can happen. Ancient astronomers were aware of these points in the sky, and by the apex of Babylonian civilization, they were very good at predicting when eclipses would occur.

Two and a half millennia later, in 2016, astronomers used these same ancient records to measure the change in the rate at which Earth’s rotation is slowing—which is to say, the amount by which are days are lengthening, over thousands of years.

By the middle of the 19 th century, scientific discoveries came at a frenetic pace, and eclipses powered many of them. In October 1868, two astronomers, Pierre Jules César Janssen and Joseph Norman Lockyer, separately measured the colors of sunlight during a total eclipse. Each found evidence of an unknown element, indicating a new discovery: Helium, named for the Greek god of the Sun. In another eclipse in 1869, astronomers found convincing evidence of another new element, which they nicknamed coronium—before learning a few decades later that it was not a new element, but highly ionized iron, indicating that the Sun’s atmosphere is exceptionally, bizarrely hot. This oddity led to the prediction, in the 1950s, of a continual outflow that we now call the solar wind.

And during solar eclipses between 1878 and 1908, astronomers searched in vain for a proposed extra planet within the orbit of Mercury. Provisionally named Vulcan, this planet was thought to exist because Newtonian gravity could not fully describe Mercury’s strange orbit. The matter of the innermost planet’s path was settled, finally, in 1915, when Einstein used general relativity equations to explain it.

Many eclipse expeditions were intended to learn something new, or to prove an idea right—or wrong. But many of these discoveries have major practical effects on us. Understanding the Sun, and why its atmosphere gets so hot, can help us predict solar outbursts that could disrupt the power grid and communications satellites. Understanding gravity, at all scales, allows us to know and to navigate the cosmos.

GPS satellites, for instance, provide accurate measurements down to inches on Earth. Relativity equations account for the effects of the Earth’s gravity and the distances between the satellites and their receivers on the ground. Special relativity holds that the clocks on satellites, which experience weaker gravity, seem to run slower than clocks under the stronger force of gravity on Earth. From the point of view of the satellite, Earth clocks seem to run faster. We can use different satellites in different positions, and different ground stations, to accurately triangulate our positions on Earth down to inches. Without those calculations, GPS satellites would be far less precise.

This year, scientists fanned out across North America and in the skies above it will continue the legacy of eclipse science. Scientists from NASA and several universities and other research institutions will study Earth’s atmosphere; the Sun’s atmosphere; the Sun’s magnetic fields; and the Sun’s atmospheric outbursts, called coronal mass ejections.

When you look up at the Sun and Moon on the eclipse , the Moon’s day — or just observe its shadow darkening the ground beneath the clouds, which seems more likely — think about all the discoveries still yet waiting to happen, just behind the shadow of the Moon.

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What is the difference between a solar eclipse and a lunar eclipse?

It almost time! Millions of Americans across the country Monday are preparing to witness the once-in-a-lifetime total solar eclipse as it passes over portions of Mexico, the United States and Canada.

It's a sight to behold and people have now long been eagerly awaiting what will be their only chance until 2044 to witness totality, whereby the moon will completely block the sun's disc, ushering in uncharacteristic darkness.

That being said, many are curious on what makes the solar eclipse special and how is it different from a lunar eclipse.

The total solar eclipse is today: Get the latest forecast and everything you need to know

What is an eclipse?

An eclipse occurs when any celestial object like a moon or a planet passes between two other bodies, obscuring the view of objects like the sun, according to NASA .

What is a solar eclipse?

A total solar eclipse occurs when the moon comes in between the Earth and the sun, blocking its light from reaching our planet, leading to a period of darkness lasting several minutes. The resulting "totality," whereby observers can see the outermost layer of the sun's atmosphere, known as the corona, presents a spectacular sight for viewers and confuses animals – causing nocturnal creatures to stir and bird and insects to fall silent.

Partial eclipses, when some part of the sun remains visible, are the most common, making total eclipses a rare sight.

What is a lunar eclipse?

A total lunar eclipse occurs when the moon and the sun are on exact opposite sides of Earth. When this happens, Earth blocks the sunlight that normally reaches the moon. Instead of that sunlight hitting the moon’s surface, Earth's shadow falls on it.

Lunar eclipses are often also referred to the "blood moon" because when the Earth's shadow covers the moon, it often produces a red color. The coloration happens because a bit of reddish sunlight still reaches the moon's surface, even though it's in Earth's shadow.

Difference between lunar eclipse and solar eclipse

The major difference between the two eclipses is in the positioning of the sun, the moon and the Earth and the longevity of the phenomenon, according to NASA.

A lunar eclipse can last for a few hours, while a solar eclipse lasts only a few minutes. Solar eclipses also rarely occur, while lunar eclipses are comparatively more frequent. While at least two partial lunar eclipses happen every year, total lunar eclipses are still rare, says NASA.

Another major difference between the two is that for lunar eclipses, no special glasses or gizmos are needed to view the spectacle and one can directly stare at the moon. However, for solar eclipses, it is pertinent to wear proper viewing glasses and take the necessary safety precautions because the powerful rays of the sun can burn and damage your retinas.

Contributing: Eric Lagatta, Doyle Rice, USA TODAY

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COMMENTS

Empirical evidence
empirical evidence, information gathered directly or indirectly through observation or experimentation that may be used to confirm or disconfirm a scientific theory or to help justify, or establish as reasonable, a person's belief in a given proposition. A belief may be said to be justified if there is sufficient evidence to make holding the belief reasonable.
Empirical Evidence
Empirical evidence is related to the philosophical distinction between a priori and a posteriori reasoning. A priori reasoning, that is, without (or 'prior' to) evidence or experience is the sort of reasoning commonly used by logicians, philosophers, and mathematicians. a posteriori reasoning is based on observation and empirical evidence.
Empirical evidence
Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and plays a role in various other fields, like epistemology and law.. There is no general agreement on how the terms evidence and empirical are to be ...
Empirical evidence: A definition
Empirical evidence is information acquired by observation or experimentation. Scientists record and analyze this data. The process is a central part of the scientific method, leading to the ...
Theory and Observation in Science
Discussions about empirical evidence have tended to focus on epistemological questions regarding its role in theory testing. This entry follows that precedent, even though empirical evidence also plays important and philosophically interesting roles in other areas including scientific discovery, the development of experimental tools and ...
What is empirical evidence
Empirical evidence, or scientific evidence, is any proof or information gathered by a researcher through thorough observation and documentation of certain behaviors or patterns using well-designed, standardized, and objective studies or experiments. The collection and analysis of empirical evidence is the focus of the scientific method.
Evidence (Stanford Encyclopedia of Philosophy)
Of course, 'evidence' is hardly a philosopher's term of art: it is not only, or even primarily, philosophers who routinely speak of evidence, but also lawyers and judges, historians and scientists, investigative journalists and reporters, as well as the members of numerous other professions and ordinary folk in the course of everyday life.
Rationalism vs. Empiricism
The dispute between rationalism and empiricism concerns the extent to which we are dependent upon sense experience in our effort to gain knowledge. Rationalists claim that there are significant ways in which our concepts and knowledge are gained independently of sense experience. Empiricists claim that sense experience is the ultimate source of ...
Sociology
Evidence. Once you have developed a working argument, you will next need to find evidence to support your claim. What counts as evidence in a sociology paper? First and foremost, sociology is an empirical discipline. Empiricism in sociology means basing your conclusions on evidence that is documented and collected with as much rigor as possible.
LibGuides: Psychology 124: Empirical Research Essay: Welcome
Empirical Research consists of experiments that rely on observation and measurement. Empirical research uses specific methods to test out theories and hypotheses (expectations) using real data instead of hunches or observations. This type of research is easily identifiable as it always consists of the following pieces of information: A distinct ...
PDF Writing Empirical Papers Beginners Guide
Writing Empirical Papers: Instructions for Beginners Connie Wolfe Muhlenberg College. Note: This guide is intended for students new to writing empirical papers. It is based on conventions used in social psychology; different sub-disciplines have additional or different requirements. The emphasis of the guide is on writing process and content.
Empirical Research
Strategies for Empirical Research in Writing is a particularly accessible approach to both qualitative and quantitative empirical research methods, helping novices appreciate the value of empirical research in writing while easing their fears about the research process. This comprehensive book covers research methods ranging from traditional ...
Empirical Research: Defining, Identifying, & Finding
If you aren't sure what is and is not empirical research, this might seem scary. We are here to help. Note: while this guide is designed to help you understand and find empirical research, you should always default to your instructor's definition if they provide one and direct any specific questions about whether a source fits that definition ...
Empirical Evidence
Empirical evidence comes in many shapes and sizes, but it is not the only type of evidence that can be used. Evidence can also be analytical, anecdotal, and logical. Empirical Data vs Analytical Data
15 Empirical Evidence Examples (2024)
Empirical Evidence Examples. Quantitative Data: Quantitative data is numerical data obtained through measurement, counting, or statistical analysis. An example is a person's test scores, which are used as empirical evidence that can get you into a prestigious university. The strength of this type of data is that it tends to be objective ...
Empirical Evidence: Definition, Uses, Types and Examples
Empirical evidence is any information you can collect through the processes of observation or investigation. You might use your five senses, measure data or design an experiment to test a hypothesis. Acquiring empirical evidence is a vital step in the scientific method, as it allows researchers to collect, organize and study data that results ...
Empirical Evidence
Empirical evidence is a quintessential part of the scientific method of research that is applicable in many disciplines. In the scientific method, the pieces of empirical evidence are used to validate or disprove a stated hypothesis, statement, or claim. In the scientific world, a hypothesis can be accepted by the community only if sufficient ...
Evidence in Essays ⇒ Examples and Types of Evidence in Writing
There are many different types of evidence that can be used in essays. Some common examples include: Analogical: An analogy or comparison that supports your argument. Example: "Like the human body, a car needs regular maintenance to function properly.".
QUT cite|write
All the research in the literature review must be cited in the text of the article and referenced in a list at the end. A literature review can be arranged in a thematic structure, where different aspects of the topic or different theories related to the topic are addressed one at a time. In some cases, a chronological order, with each piece or ...
Rationalism vs. Empiricism
The dispute between rationalism and empiricism takes place primarily within epistemology, the branch of philosophy devoted to studying the nature, sources, and limits of knowledge. Knowledge itself can be of many different things and is usually divided among three main categories: knowledge of the external world, knowledge of the internal world ...
What is Empirical Evidence?
Empirical evidence is information that researchers generate to help uncover answers to questions that can have significant implications for our society. Take seatbelts. Prior to their invention, people were killed or maimed in what today we would think of as minor traffic accidents. So smart engineers put their heads together to try to do ...
Writing a useful empirical journal article
Because this essay will appear in the Journal of Management Scientific Reports, I emphasize the reporting of tests of theory rather than the creation of new theory. I argue that good writing matches the needs of the intended reader, and thus authors must consider what readers need to understand and trust reported empirical evidence.
Empirical Evidence Should Be Used To Make Progress Philosophy Essay
Empirical evidence is defined as evidence relying on experience or observation alone often without due regard for system and theory [] . The meaning of the word empirical derives from the ancient Greek word for experience (ÎµÎ¼Ï€ÎµÎ¹Ï Î¯Î±), which means knowledge based on direct perception of things or events through our senses.
Sustainability
The concept of "green development" has garnered increasing recognition and prominence in recent years, attracting the attention of various countries and regions. How to achieve green development has become a pressing issue for the government. The integration of the culture industry and tourism has had a profound impact on regional green development. This paper employs the entropy method to ...
What the World Has Learned From Past Eclipses
"Lights All Askew In the Heavens," the New York Times proclaimed when the scientific papers were published. The eclipse was the key to the discovery—as so many solar eclipses before and ...
Solar vs. lunar eclipse: The different types of eclipses, explained
The major difference between the solar eclipse and the lunar eclipse is the positioning of the sun, the moon and the earth, according to NASA.