examples of valid argument in critical thinking

Pursuing Truth: A Guide to Critical Thinking

Chapter 2 arguments.

The fundamental tool of the critical thinker is the argument. For a good example of what we are not talking about, consider a bit from a famous sketch by Monty Python’s Flying Circus : 3

2.1 Identifying Arguments

People often use “argument” to refer to a dispute or quarrel between people. In critical thinking, an argument is defined as

A set of statements, one of which is the conclusion and the others are the premises.

There are three important things to remember here:

• Arguments contain statements.
• They have a conclusion.
• They have at least one premise

Arguments contain statements, or declarative sentences. Statements, unlike questions or commands, have a truth value. Statements assert that the world is a particular way; questions do not. For example, if someone asked you what you did after dinner yesterday evening, you wouldn’t accuse them of lying. When the world is the way that the statement says that it is, we say that the statement is true. If the statement is not true, it is false.

One of the statements in the argument is called the conclusion. The conclusion is the statement that is intended to be proved. Consider the following argument:

Calculus II will be no harder than Calculus I. Susan did well in Calculus I. So, Susan should do well in Calculus II.

Here the conclusion is that Susan should do well in Calculus II. The other two sentences are premises. Premises are the reasons offered for believing that the conclusion is true.

2.1.1 Standard Form

Now, to make the argument easier to evaluate, we will put it into what is called “standard form.” To put an argument in standard form, write each premise on a separate, numbered line. Draw a line underneath the last premise, the write the conclusion underneath the line.

• Calculus II will be no harder than Calculus I.
• Susan did well in Calculus I.
• Susan should do well in Calculus II.

Now that we have the argument in standard form, we can talk about premise 1, premise 2, and all clearly be referring to the same thing.

2.1.2 Indicator Words

Unfortunately, when people present arguments, they rarely put them in standard form. So, we have to decide which statement is intended to be the conclusion, and which are the premises. Don’t make the mistake of assuming that the conclusion comes at the end. The conclusion is often at the beginning of the passage, but could even be in the middle. A better way to identify premises and conclusions is to look for indicator words. Indicator words are words that signal that statement following the indicator is a premise or conclusion. The example above used a common indicator word for a conclusion, ‘so.’ The other common conclusion indicator, as you can probably guess, is ‘therefore.’ This table lists the indicator words you might encounter.

Each argument will likely use only one indicator word or phrase. When the conlusion is at the end, it will generally be preceded by a conclusion indicator. Everything else, then, is a premise. When the conclusion comes at the beginning, the next sentence will usually be introduced by a premise indicator. All of the following sentences will also be premises.

For example, here’s our previous argument rewritten to use a premise indicator:

Susan should do well in Calculus II, because Calculus II will be no harder than Calculus I, and Susan did well in Calculus I.

Sometimes, an argument will contain no indicator words at all. In that case, the best thing to do is to determine which of the premises would logically follow from the others. If there is one, then it is the conclusion. Here is an example:

Spot is a mammal. All dogs are mammals, and Spot is a dog.

The first sentence logically follows from the others, so it is the conclusion. When using this method, we are forced to assume that the person giving the argument is rational and logical, which might not be true.

2.1.3 Non-Arguments

One thing that complicates our task of identifying arguments is that there are many passages that, although they look like arguments, are not arguments. The most common types are:

• Explanations
• Mere asssertions
• Conditional statements
• Loosely connected statements

Explanations can be tricky, because they often use one of our indicator words. Consider this passage:

Abraham Lincoln died because he was shot.

If this were an argument, then the conclusion would be that Abraham Lincoln died, since the other statement is introduced by a premise indicator. If this is an argument, though, it’s a strange one. Do you really think that someone would be trying to prove that Abraham Lincoln died? Surely everyone knows that he is dead. On the other hand, there might be people who don’t know how he died. This passage does not attempt to prove that something is true, but instead attempts to explain why it is true. To determine if a passage is an explanation or an argument, first find the statement that looks like the conclusion. Next, ask yourself if everyone likely already believes that statement to be true. If the answer to that question is yes, then the passage is an explanation.

Mere assertions are obviously not arguments. If a professor tells you simply that you will not get an A in her course this semester, she has not given you an argument. This is because she hasn’t given you any reasons to believe that the statement is true. If there are no premises, then there is no argument.

Conditional statements are sentences that have the form “If…, then….” A conditional statement asserts that if something is true, then something else would be true also. For example, imagine you are told, “If you have the winning lottery ticket, then you will win ten million dollars.” What is being claimed to be true, that you have the winning lottery ticket, or that you will win ten million dollars? Neither. The only thing claimed is the entire conditional. Conditionals can be premises, and they can be conclusions. They can be parts of arguments, but that cannot, on their own, be arguments themselves.

Finally, consider this passage:

I woke up this morning, then took a shower and got dressed. After breakfast, I worked on chapter 2 of the critical thinking text. I then took a break and drank some more coffee….

This might be a description of my day, but it’s not an argument. There’s nothing in the passage that plays the role of a premise or a conclusion. The passage doesn’t attempt to prove anything. Remember that arguments need a conclusion, there must be something that is the statement to be proved. Lacking that, it simply isn’t an argument, no matter how much it looks like one.

2.2 Evaluating Arguments

The first step in evaluating an argument is to determine what kind of argument it is. We initially categorize arguments as either deductive or inductive, defined roughly in terms of their goals. In deductive arguments, the truth of the premises is intended to absolutely establish the truth of the conclusion. For inductive arguments, the truth of the premises is only intended to establish the probable truth of the conclusion. We’ll focus on deductive arguments first, then examine inductive arguments in later chapters.

Once we have established that an argument is deductive, we then ask if it is valid. To say that an argument is valid is to claim that there is a very special logical relationship between the premises and the conclusion, such that if the premises are true, then the conclusion must also be true. Another way to state this is

An argument is valid if and only if it is impossible for the premises to be true and the conclusion false.

An argument is invalid if and only if it is not valid.

Note that claiming that an argument is valid is not the same as claiming that it has a true conclusion, nor is it to claim that the argument has true premises. Claiming that an argument is valid is claiming nothing more that the premises, if they were true , would be enough to make the conclusion true. For example, is the following argument valid or not?

• If pigs fly, then an increase in the minimum wage will be approved next term.
• An increase in the minimum wage will be approved next term.

The argument is indeed valid. If the two premises were true, then the conclusion would have to be true also. What about this argument?

• All dogs are mammals
• Spot is a mammal.
• Spot is a dog.

In this case, both of the premises are true and the conclusion is true. The question to ask, though, is whether the premises absolutely guarantee that the conclusion is true. The answer here is no. The two premises could be true and the conclusion false if Spot were a cat, whale, etc.

Neither of these arguments are good. The second fails because it is invalid. The two premises don’t prove that the conclusion is true. The first argument is valid, however. So, the premises would prove that the conclusion is true, if those premises were themselves true. Unfortunately, (or fortunately, I guess, considering what would be dropping from the sky) pigs don’t fly.

These examples give us two important ways that deductive arguments can fail. The can fail because they are invalid, or because they have at least one false premise. Of course, these are not mutually exclusive, an argument can be both invalid and have a false premise.

If the argument is valid, and has all true premises, then it is a sound argument. Sound arguments always have true conclusions.

A deductively valid argument with all true premises.

Inductive arguments are never valid, since the premises only establish the probable truth of the conclusion. So, we evaluate inductive arguments according to their strength. A strong inductive argument is one in which the truth of the premises really do make the conclusion probably true. An argument is weak if the truth of the premises fail to establish the probable truth of the conclusion.

There is a significant difference between valid/invalid and strong/weak. If an argument is not valid, then it is invalid. The two categories are mutually exclusive and exhaustive. There can be no such thing as an argument being more valid than another valid argument. Validity is all or nothing. Inductive strength, however, is on a continuum. A strong inductive argument can be made stronger with the addition of another premise. More evidence can raise the probability of the conclusion. A valid argument cannot be made more valid with an additional premise. Why not? If the argument is valid, then the premises were enough to absolutely guarantee the truth of the conclusion. Adding another premise won’t give any more guarantee of truth than was already there. If it could, then the guarantee wasn’t absolute before, and the original argument wasn’t valid in the first place.

2.3 Counterexamples

One way to prove an argument to be invalid is to use a counterexample. A counterexample is a consistent story in which the premises are true and the conclusion false. Consider the argument above:

By pointing out that Spot could have been a cat, I have told a story in which the premises are true, but the conclusion is false.

Here’s another one:

• If it is raining, then the sidewalks are wet.
• The sidewalks are wet.
• It is raining.

The sprinklers might have been on. If so, then the sidewalks would be wet, even if it weren’t raining.

Counterexamples can be very useful for demonstrating invalidity. Keep in mind, though, that validity can never be proved with the counterexample method. If the argument is valid, then it will be impossible to give a counterexample to it. If you can’t come up with a counterexample, however, that does not prove the argument to be valid. It may only mean that you’re not creative enough.

• An argument is a set of statements; one is the conclusion, the rest are premises.
• The conclusion is the statement that the argument is trying to prove.
• The premises are the reasons offered for believing the conclusion to be true.
• Explanations, conditional sentences, and mere assertions are not arguments.
• Deductive reasoning attempts to absolutely guarantee the truth of the conclusion.
• Inductive reasoning attempts to show that the conclusion is probably true.
• In a valid argument, it is impossible for the premises to be true and the conclusion false.
• In an invalid argument, it is possible for the premises to be true and the conclusion false.
• A sound argument is valid and has all true premises.
• An inductively strong argument is one in which the truth of the premises makes the the truth of the conclusion probable.
• An inductively weak argument is one in which the truth of the premises do not make the conclusion probably true.
• A counterexample is a consistent story in which the premises of an argument are true and the conclusion is false. Counterexamples can be used to prove that arguments are deductively invalid.

( Cleese and Chapman 1980 ) . ↩︎

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Critical thinking arguments for beginners

Critical thinking is one of the most valuable sets of life skills you can ever have and it’s never too late to learn them. People who can think critically are better at problem solving of all kinds, whether at school or work, in ordinary daily life, and even in crises. You can practice critical thinking by working through typical arguments from premises to conclusions.

Thinking critically isn’t about following a single path to an inevitable conclusion. It’s about developing a set of powerful and versatile mental processing tools in your head and being able to apply these meaningfully to the world around you.

You need no special qualifications to become a strong critical thinker, and can’t pick it up simply from reading books about critical thinking. The only way to hone critical thinking skills is to practice critical thinking.

If you’re ready to learn more about critical thinking arguments for beginners then read on…

What is critical thinking?

Let’s first illustrate the answer to this question by taking a look at how we can think critically about potential misinformation online.

Your friend on a social media site has shared a photograph of election ballot slips apparently being tipped into a river by a postal truck driver, reportedly a supporter of a political party who will benefit from lower postal voter turnout.

Your friend is a supporter of another party and expresses outrage at the alleged law-breaking, election influencing, and reduced chances for her own party candidate. Many other friends pile in with sympathetic and equally outraged comments, or new allegations.

The temptation might be strong to accept the narrative caption which accompanies the picture, echo your friends’ emotional responses, and share the photo further. However, as a critical thinker, you should step back and ask some crucial questions first:

• Is the photo obviously manipulated? Sophisticated image alterations can now be made which won’t be spotted by the majority of non-experts. Could this be an image of a simple truck crash with ballot papers photoshopped in?
• Does your friend fact-check stories, pictures, memes etc.. before posting them online? If she has a history of posting stories which turned out to be false, it reduces her credibility in presenting the current story.
• I s there anything in the photograph which supports or undermines the claims made? If you can see that the van has a foreign registration plate, the ballot papers aren’t in English, or the date on the clock is actually several years ago, it is clear that the true story is somewhat different to the one being told.

Let’s say that your initial suspicions after asking yourself these questions are enough that you do a quick web search for the story.

Your search reveals that credible sources have already uncovered the photo as having been manipulated and spread by an online political group. It was originally a local news story about a crashed postal truck in another country five years earlier and has no relationship whatsoever to the current election in your country…

Your critical thinking helped you to avoid falling into group-think along with your friends and saved you from spreading more misinformation online. These real life type examples are are an excellent way to grasp the relevance and value of critical thinking arguments for beginners.

Now for a little of the theory. Critical thinking is a description that brings together a range of useful intellectual skills and their synergies. While there is no definitive list, there are some common key competences necessary for critical thinking:

• Conducting analysis. Being able to understand the issue in question; distinguish between relevant and irrelevant information; identify commonalities, differences and connections.
• Making inferences. Using inductive or deductive reasoning to draw out meanings; identifying assumptions; abstracting ideas; applying analogies and recognizing cause and effect relationships in order to develop theories or potential conclusions.
• Evaluating evidence. Making a judgement about whether a theory or statement is credible or correct; adjusting views and theories in the light of new data or perspectives; grasping the significance of events and information.
• Making robust decisions. Reaching sound conclusions by applying critical thinking skills to the available evidence.

To apply critical thinking in real life, you also need to possess the right attitude to problem solving, as well as the critical thinking skills themselves.

This means being automatically inclined to think critically in the face of a difficult question or problem. Being fair, open-minded, curious and free from ideology or group-think will all help to create a mindset in which critical thinking can thrive.

What are critical thinking arguments?

Let’s now look at some of the basic building blocks underpinning critical thinking arguments for beginners.

In critical thinking and logic, ‘argument’ has a particular meaning. It refers to a set of statements, consisting of one conclusion and one or more premises. The conclusion is the statement that the argument is intended to prove. The premises are the reasons offered for believing that the conclusion is true.

A critical thinking argument could use a deductive reasoning approach, an inductive reasoning approach, or both.

Deductive reasoning

Deductive reasoning attempts to absolutely guarantee a conclusion’s truth through logic. If a deductive argument’s premises are true, it should be impossible for its conclusion to be false. For example:

• All humans are mortal. (Premise)
• Socrates is a human. (Premise)
• Therefore, Socrates is mortal.  (Conclusion)

Inductive reasoning

Inductive reasoning attempts to show that the conclusion is probably true, with each premise making the case for the conclusion stronger or weaker. For example:

• Three independent witnesses saw Max climb in through the window of the house. (Premise)
• Max’s fingerprints are on the window frame and several stolen items. (Premise)
• Max confessed to the burglary. (Premise)
• Therefore, Max committed the burglary. (Conclusion)

Do note that in either case, straight assertions, explanations or conditional sentences are not arguments.

How do I assess a critical thinking argument?

You can evaluate whether an argument is valid or invalid, sound or unsound, strong or weak .

If an argument is said to be ‘valid’, it means that it is impossible for the conclusion to be false if the premises are true. If an argument is ‘invalid’, it is possible for the premises to be true and the conclusion false.

An argument is ‘sound’ if it is both valid and contains only true premises. If either of these conditions isn’t met then the argument is ‘unsound’.

A deductively ‘strong’ argument is both valid and it is reasonable for the person in question to believe the premises are true. In a deductively weak argument , the person considering the premises may have good reason to doubt them.

When an argument is inductively strong, the truth of the premises makes the the truth of the conclusion probable. In contrast, in an inductively ‘weak’ argument, the truth of the premises do not make the truth of the conclusion probable.

Counterexamples

A ‘counterexample’ is a consistent story which shows that an argument can have true premises but a false conclusion, rendering it invalid.

NB A valid argument is not necessarily true, and a weak argument is not necessarily false.

All of these fundamentals can be applied both to simple practice arguments and then to more complex problems of the type you might encounter in real life.

For example:

• All unicorns are Swedish (Premise)
• My new pet is a unicorn (Premise)
• Therefore,  my new pet is Swedish (Conclusion)

The premises here are both false – unicorns do not exist, and I therefore cannot own one as a pet. However, if they were true, then the conclusion would be true. What we have here is a valid argument, but not a sound one, nor a strong one.

How can I practice critical thinking arguments for beginners?

Now that you have the basic tools and concepts for putting together a critical thinking argument, you can look  out for real life examples to practice with.

News stories

Look at the headlines covering stories in TV,  online or paper news. Do you agree that the facts of the story are credible and constitute premises strong enough to justify the headline drawn from them?

Social media

Critically examine stories and claims shared by friends and contacts online. Ask yourself whether the evidence presented is credible and justifies the claims being made.

Corporate statements

Evaluate claims made by big corporations in public statements and annual reports alongside their actions and impacts. For example, if a major oil company claims that it is working to combat climate change, how strong, valid and sound are their arguments?

Conclusion…

Whatever your starting point, we hope this article has set you on the road to becoming a critical thinker, and that these developing skills might open new doors at school, at work or in other areas of life. The world needs more critical thinking at all levels and your contribution might one day be valuable.

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Definition and Examples of Valid Arguments

Glossary of Grammatical and Rhetorical Terms

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• An Introduction to Punctuation
• Ph.D., Rhetoric and English, University of Georgia
• M.A., Modern English and American Literature, University of Leicester
• B.A., English, State University of New York

In a deductive argument , validity is the principle that if all the premises are true, the conclusion must also be true. Also known as formal validity and valid argument. 

In logic , validity isn't the same as truth . As Paul Tomassi observes, "Validity is a property of arguments. Truth is a property of individual sentences . Moreover, not every valid argument is a sound argument" ( Logic , 1999). According to a popular slogan, "Valid arguments are valid by virtue of their form" (although not all logicians would wholly agree). Arguments that are not valid are said to be invalid.

In rhetoric , says James Crosswhite, "a valid argument is one which wins the assent of a universal audience . A merely effective argument succeeds only with a particular audience" ( The Rhetoric of Reason , 1996). Put another way, validity is the product of rhetorical competence.

Formally Valid Arguments

"A formally valid argument that has true premises is said to be a sound argument. In debate or discussion, therefore, an argument may be attacked in two ways: by attempting to show that one of its premises is false or by attempting to show that it is invalid. On the other hand, if one concedes the truth of the premises of a formally valid argument, one must also concede the truth of the conclusion—or be guilty of irrationality." (Martin P. Golding, Legal Reasoning . Broadview Press, 2001)

"... I once heard former RIBA President Jack Pringle defend flat roofs with the following syllogism : We all like Edwardian terraces. Edwardian terraces use curtain walls to hide their sloping roofs and pretend they're flat. Ergo: we must all like flat roofs. Except that we don't, and they still leak." (Jonathan Morrison, "My Top Five Architectural Pet Hates." The Guardian , November 1, 2007)

Analyzing the Validity of An Argument

"The primary tool in deductive reasoning is the syllogism, a three-part argument consisting of two premises and a conclusion:

All Rembrandt paintings are great works of art. The Night Watch is a Rembrandt painting. Therefore, The Night Watch is a great work of art.

All doctors are quacks. Smith is a doctor. Therefore, Smith is a quack.

The syllogism is a tool for analyzing the validity of an argument. You'll rarely find a formal syllogism outside of textbooks on logic . Mostly, you'll find enthymemes , abbreviated syllogisms with one or more of the parts unstated:

The Night Watch is by Rembrandt, isn't it? And Rembrandt is a great painter, isn't he?

Look, Smith is a doctor. He must be a quack.

Translating such statements into a syllogism enables the logic to be examined more coolly and clearly than it otherwise could be. If both premises in a syllogism are true and the reasoning process from one part of the syllogism to the other is valid, the conclusions will be proven." (Sarah Skwire and David Skwire, Writing With a Thesis: A Rhetoric and Reader , 12th ed. Wadsworth, Cengage, 2014)

Valid Argument Forms

"There are a great many valid argument forms, but we shall consider only four basic ones. They are basic in the sense that they occur in everyday use, and that all other valid argument forms can be derived from these four forms:

Affirming the Antecedent

If p then q. p. Therefore, q.

Denying the Consequent

If p then q. Not-q. Therefore, not-p.

Chain Argument

If p then q. If q then r. Therefore, if p then r.

Disjunctive Syllogism

Either p or q. Not-p. Therefore, q.

Whenever we find an argument whose form is identical to one of these valid argument forms, we know that it must be a valid argument." (William Hughes and Jonathan Lavery, Critical Thinking: An Introduction to the Basic Skills . Broadview Press, 2004)

• What Is Deductive Reasoning?
• Definition and Examples of Syllogisms
• How to Prove an Argument Invalid by a Counterexample
• Definition and Examples of Sorites in Rhetoric
• Premise Definition and Examples in Arguments
• How Logical Fallacy Invalidates Any Argument
• Undistributed Middle (Fallacy)
• Propositions in Debate Definition and Examples
• Definition and Examples of Conclusions in Arguments
• paralogism (rhetoric and logic)
• Induction (Logic and Rhetoric)
• Contradictory Premises in an Argument
• What Is a Converse Error?
• Enthymeme - Definition and Examples
• Inference in Arguments

• What Is a Valid Argument? Critical Thinking basics

By Andreas Matthias

In a valid argument, it is not possible that the conclusion is false when the premises are true. Or, in other words: In a valid argument, whenever the premises are true, the conclusion also has to be true.

This article is part of a series on Logic and Critical Thinking. Find all the articles in this series here .

If you like reading about philosophy, here's a free, weekly newsletter with articles just like this one: Send it to me!

We use “valid” in many different ways in everyday life. We say things like “that’s a valid point,” or “his credit card number was not valid.” But in logic, “valid” has a very special meaning. Read on to learn how to use “valid” for arguments.

What does “valid” mean?

Easy enough. Every argument consists of a number of statements, called the premises, which together offer support for the belief that another statement, called the conclusion , is true. For example:

Premise 1: If I am hungry, I will go to the restaurant down the street. Premise 2: I am hungry. Conclusion: I will go to the restaurant down the street.

Here, the premises, taken together, support the belief that the conclusion is true.

It is important that in a valid argument the premises make it certain (not only likely) that the conclusion is true. In the example above, assuming that the premises are true, the conclusion must also be true. If the conclusion was not true, then at least one of the premises would also not be true.

An argument like that is called a deductive argument. On the other hand, if the premises only make it likely, but not certain,* that the conclusion is true, then the argument is called an inductive argument. For example:

Premise 1: If I am hungry, I sometimes go to the restaurant down the street. Premise 2: I am hungry. Conclusion: I go to the restaurant down the street.

Here it is not certain that I will indeed go to that restaurant, because I do so only sometimes. So this time might be one of the times where I don’t go there. From this argument alone it is not possible to be sure about whether I will go to that restaurant or not.

Invalid and not-valid arguments

It is important to see that only deductive arguments can be valid. Do you see why? We said that:

In a valid argument, it is not possible that the conclusion is false when the premises are true.

And also that a deductive argument is one where the conclusion is certain; while an inductive argument is one where the conclusion is probable, but not certain.

Now, if we require that “it is not possible” that the conclusion is false when the premises are true, then necessarily we need valid arguments to be deductive, since only deductive arguments allow us to be certain of their conclusions.

This brings with it a little difficulty about how we should speak about arguments that are not valid. Clearly, following our definitions, no inductive argument can be valid; so how do we call inductive arguments? We could call them “invalid,” since they are not valid. But this creates the problem that, if all inductive arguments were considered “invalid,” how would we go about distinguishing between “better” and “worse” inductive arguments?

For example, look at these two arguments:

Premise 1: If I am hungry, I almost never go to the restaurant down the street. Premise 2: I am not even hungry now. Conclusion: I go to the restaurant down the street.

Obviously, although none of the two conclusions is certain, the first argument’s conclusion is much more probable to be true than the second one. The second is so improbable that we would actually like to say that it is almost totally out of the question. This second argument offers practically no support at all for its conclusion. So we would like to say that it is invalid in the sense that it constitutes a “fallacy,” or an error in argumentation. (Look at this article for a gentle and detailed explanation of different fallacies.)

But if we reserve “invalid” for “bad” arguments, then how do we call arguments like the first one just above? They are “good” arguments, but they are not “valid,” since for a valid argument that conclusion must be certain.

So this is why we usually speak of arguments that are:

• “Valid” (deductive arguments, conclusion is certain to be true);
• “Non-valid” (inductive arguments, strong or weak, conclusion is more or less probable);
• and “invalid” (bad arguments, both deductive and inductive, where the conclusion is not supported by the premises at all).

Other books and teachers of logic prefer a different categorisation:

• “Invalid” (inductive arguments, strong or weak, conclusion is more or less probable), plus deductive arguments that are not valid;
• and “bad” inductive arguments (where the conclusion is not supported by the premises at all).

This is really a matter of taste. It comes down to the fact that we need three different categories, but the valid/invalid dichotomy gives us only two; so we have to decide what we want “invalid” to mean in regard to inductive arguments (which can never be valid, but they can still be “good” arguments).

Valid and sound arguments

Another interesting point is the distinction between “valid” and “sound” arguments.

We call valid arguments with true premises (and therefore a true conclusion), sound arguments.

Look at this example:

Premise 1: Hong Kong is in the south of China. Premise 2: Beijing is in the north of China. Premise 3: The south of China is warmer than the north of China. Conclusion: Hong Kong is warmer than Beijing.

This is valid and its premises are true. So this is a sound argument.

On the other hand:

Premise 1: Elephants are smaller than goldfish. Premise 2: Goldfish are smaller than ants. Conclusion: Therefore, elephants are smaller than ants.

In this second case, the premises are clearly not true. But what would happen if they were true? Let’s for a moment assume that we live on an alternative Earth, in which these two premises are true: in which elephants are smaller than goldfish and goldfish are smaller than ants. Would then elephants be smaller than ants? — Clearly, yes. They would have to be!

So, to go back to the definition of a valid argument: If we assume that the premises of the last argument above were true, then the conclusion would have to be true also; and this makes it a valid argument. So for the validity of the argument it does not matter whether the premises are actually true or not. Only whether if they were true the conclusion would have to be true, which is the case here.

But, since the premises are not actually true, this argument is valid but not sound. (Remember that in sound arguments that premises have to actually be true.)

Valid arguments with contradictory premises

This brings us to a last point that is easy to overlook. Is the following argument valid?

Premise 1: New York is in Russia. Premise 2: New York is not in Russia. Conclusion: Germany is in Africa.

You might be tempted to say no. But look again at the definition of validity:

Or, in other words: a valid argument can never have true premises and a false conclusion. What about this here? Can it have true premises and a false conclusion? Or, just ignore the conclusion: can this ever have true premises?

No. This argument can never have both premises be true, simply because the two premises contradict each other. Wherever New York may be, it cannot be both in Russia and not in Russia. One of the two premises will always have to be true and the other will have to be false.

So, in this case, it is impossible that we have (all) true premises and a false conclusion, simply because we cannot have all premises be true at the same time. Consequently, following our definition, this argument is valid, since it is impossible for it to have true premises and a false conclusion (but the conclusion doesn’t matter in this case; it cannot have true premises, period).

In summary, if an argument has contradictory premises, it is always valid, no matter what the premises or the conclusion are. Conversely, such an argument can never be sound, because this would require both its premises to be true, which cannot happen if they contradict each other.

What are “good” arguments?

Now, we might be confused about people using “valid” to mean “good” (as in: “this is a valid point”). If we speak in terms of logic, “good” is different from “valid.” You saw above the argument with New York being in Russia. This is valid, but nobody would call this a “good” argument.

Also, have a look at that:

Premise 1: It is 7:30 in the morning. Premise 2: My bedroom walls are painted white. Conclusion: It will rain today or it will not rain today.

Is this a valid argument? Actually, it is. The conclusion can never be false, so if the premises are true, the conclusion will also be true (since it can never be false). But is it a good argument? No, because the premises don’t actually give any support to the conclusion.

Another problem we can see here:

Premise 1: It is 7:30 in the morning. Premise 2: My bedroom walls are painted white. Conclusion: Therefore, it is now raining outside.

Even assuming that both premises and the conclusion are true, nobody would think that this is a good argument. Why? Because the premises don’t give any support to the conclusion. If the conclusion is true, it is only accidentally true and not because these particular premises contribute to its truth. So the premises, besides being true, must also be relevant to the argument’s conclusion.

Or, how about this:

Premise 1: I like ice-cream. Conclusion: Therefore, I like ice-cream.

Is it valid? Certainly. Is the premise true? Yes. Is it therefore a sound argument? Yes. Is it a good argument? Not so much. We feel that it lacks evidence for its conclusion, because the conclusion just repeats the premise. This argument is circular.

What can we conclude from all this?

A good argument is one where the premises provide strong reasons to believe in the truth of the conclusion. That means that a good argument:

• if it is a deductive argument, it should be sound (and, therefore, also valid);
• if it is an inductive argument, it should be strong;
• its premises should be relevant to the conclusion;
• and it should not be circular, contain a contradiction in its premises, or have a conclusion that is always true.

That’s all about valid and invalid, good and bad and sound arguments. If you enjoyed this and would like to read more, you can subscribe right here. If you have questions or something to add, please feel free to leave a comment!

Andreas Matthias on Daily Philosophy:

• Christopher Hamilton: Rapture. Book review
• Islam in 10 Minutes. Its history and main ideas
• Robert Rodriguez on Hermits. Philosopher interviews
• Quiet Quitting. The Accented Philosophy Podcast
• Plato’s Symposium - Part 1. An introduction
• Kant’s Ethics: What is a Categorical Imperative? A Daily Philosophy primer
• Decluttering the Mind. Erich Fromm on material possessions
• Are We Allowed to Destroy Art? Jimmy Carr is taking a hammer to Hitler
• What is Cultural Appropriation? Making sense of a difficult concept

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2 Logic and the Study of Arguments

If we want to study how we ought to reason (normative) we should start by looking at the primary way that we do reason (descriptive): through the use of arguments. In order to develop a theory of good reasoning, we will start with an account of what an argument is and then proceed to talk about what constitutes a “good” argument.

I. Arguments

• Arguments are a set of statements (premises and conclusion).
• The premises provide evidence, reasons, and grounds for the conclusion.
• The conclusion is what is being argued for.
• An argument attempts to draw some logical connection between the premises and the conclusion.
• And in doing so, the argument expresses an inference: a process of reasoning from the truth of the premises to the truth of the conclusion.

Example : The world will end on August 6, 2045. I know this because my dad told me so and my dad is smart.

In this instance, the conclusion is the first sentence (“The world will end…”); the premises (however dubious) are revealed in the second sentence (“I know this because…”).

II. Statements

Conclusions and premises are articulated in the form of statements . Statements are sentences that can be determined to possess or lack truth. Some examples of true-or-false statements can be found below. (Notice that while some statements are categorically true or false, others may or may not be true depending on when they are made or who is making them.)

Examples of sentences that are statements:

• It is below 40°F outside.
• Oklahoma is north of Texas.
• The Denver Broncos will make it to the Super Bowl.
• Russell Westbrook is the best point guard in the league.
• I like broccoli.
• I shouldn’t eat French fries.
• Time travel is possible.
• If time travel is possible, then you can be your own father or mother.

However, there are many sentences that cannot so easily be determined to be true or false. For this reason, these sentences identified below are not considered statements.

• Questions: “What time is it?”
• Commands: “Do your homework.”
• Requests: “Please clean the kitchen.”
• Proposals: “Let’s go to the museum tomorrow.”

Question: Why are arguments only made up of statements?

First, we only believe statements . It doesn’t make sense to talk about believing questions, commands, requests or proposals. Contrast sentences on the left that are not statements with sentences on the right that are statements:

It would be non-sensical to say that we believe the non-statements (e.g. “I believe what time is it?”). But it makes perfect sense to say that we believe the statements (e.g. “I believe the time is 11 a.m.”). If conclusions are the statements being argued for, then they are also ideas we are being persuaded to believe. Therefore, only statements can be conclusions.

Second, only statements can provide reasons to believe.

• Q: Why should I believe that it is 11:00 a.m.? A: Because the clock says it is 11a.m.
• Q: Why should I believe that we are going to the museum tomorrow? A: Because today we are making plans to go.

Sentences that cannot be true or false cannot provide reasons to believe. So, if premises are meant to provide reasons to believe, then only statements can be premises.

III. Representing Arguments

As we concern ourselves with arguments, we will want to represent our arguments in some way, indicating which statements are the premises and which statement is the conclusion. We shall represent arguments in two ways. For both ways, we will number the premises.

In order to identify the conclusion, we will either label the conclusion with a (c) or (conclusion). Or we will mark the conclusion with the ∴ symbol

Example Argument:

There will be a war in the next year. I know this because there has been a massive buildup in weapons. And every time there is a massive buildup in weapons, there is a war. My guru said the world will end on August 6, 2045.

• There has been a massive buildup in weapons.
• Every time there has been a massive buildup in weapons, there is a war.

(c) There will be a war in the next year.

∴ There will be a war in the next year.

Of course, arguments do not come labeled as such. And so we must be able to look at a passage and identify whether the passage contains an argument and if it does, we should also be identify which statements are the premises and which statement is the conclusion. This is harder than you might think!

There is no argument here. There is no statement being argued for. There are no statements being used as reasons to believe. This is simply a report of information.

The following are also not arguments:

Advice: Be good to your friends; your friends will be good to you.

Warnings: No lifeguard on duty. Be careful.

Associated claims: Fear leads to anger. Anger leads to the dark side.

When you have an argument, the passage will express some process of reasoning. There will be statements presented that serve to help the speaker building a case for the conclusion.

IV. How to L ook for A rguments [1]

How do we identify arguments in real life? There are no easy, mechanical rules, and we usually have to rely on the context in order to determine which are the premises and the conclusions. But sometimes the job can be made easier by the presence of certain premise or conclusion indicators. For example, if a person makes a statement, and then adds “this is because …,” then it is quite likely that the first statement is presented as a conclusion, supported by the statements that come afterward. Other words in English that might be used to indicate the premises to follow include:

• firstly, secondly, …
• for, as, after all
• assuming that, in view of the fact that
• follows from, as shown / indicated by
• may be inferred / deduced / derived from

Of course whether such words are used to indicate premises or not depends on the context. For example, “since” has a very different function in a statement like “I have been here since noon,” unlike “X is an even number since X is divisible by 4.” In the first instance (“since noon”) “since” means “from.” In the second instance, “since” means “because.”

Conclusions, on the other hand, are often preceded by words like:

• therefore, so, it follows that
• hence, consequently
• suggests / proves / demonstrates that
• entails, implies

Here are some examples of passages that do not contain arguments.

1. When people sweat a lot they tend to drink more water. [Just a single statement, not enough to make an argument.]

2. Once upon a time there was a prince and a princess. They lived happily together and one day they decided to have a baby. But the baby grew up to be a nasty and cruel person and they regret it very much. [A chronological description of facts composed of statements but no premise or conclusion.]

3. Can you come to the meeting tomorrow? [A question that does not contain an argument.]

Do these passages contain arguments? If so, what are their conclusions?

• Cutting the interest rate will have no effect on the stock market this time around, as people have been expecting a rate cut all along. This factor has already been reflected in the market.
• So it is raining heavily and this building might collapse. But I don’t really care.
• Virgin would then dominate the rail system. Is that something the government should worry about? Not necessarily. The industry is regulated, and one powerful company might at least offer a more coherent schedule of services than the present arrangement has produced. The reason the industry was broken up into more than 100 companies at privatization was not operational, but political: the Conservative government thought it would thus be harder to renationalize (The Economist 12/16/2000).
• Bill will pay the ransom. After all, he loves his wife and children and would do everything to save them.
• All of Russia’s problems of human rights and democracy come back to three things: the legislature, the executive and the judiciary. None works as well as it should. Parliament passes laws in a hurry, and has neither the ability nor the will to call high officials to account. State officials abuse human rights (either on their own, or on orders from on high) and work with remarkable slowness and disorganization. The courts almost completely fail in their role as the ultimate safeguard of freedom and order (The Economist 11/25/2000).
• Most mornings, Park Chang Woo arrives at a train station in central Seoul, South Korea’s capital. But he is not commuter. He is unemployed and goes there to kill time. Around him, dozens of jobless people pass their days drinking soju, a local version of vodka. For the moment, middle-aged Mr. Park would rather read a newspaper. He used to be a bricklayer for a small construction company in Pusan, a southern port city. But three years ago the country’s financial crisis cost him that job, so he came to Seoul, leaving his wife and two children behind. Still looking for work, he has little hope of going home any time soon (The Economist 11/25/2000).
• For a long time, astronomers suspected that Europa, one of Jupiter’s many moons, might harbour a watery ocean beneath its ice-covered surface. They were right. Now the technique used earlier this year to demonstrate the existence of the Europan ocean has been employed to detect an ocean on another Jovian satellite, Ganymede, according to work announced at the recent American Geo-physical Union meeting in San Francisco (The Economist 12/16/2000).
• There are no hard numbers, but the evidence from Asia’s expatriate community is unequivocal. Three years after its handover from Britain to China, Hong Kong is unlearning English. The city’s gweilos (Cantonese for “ghost men”) must go to ever greater lengths to catch the oldest taxi driver available to maximize their chances of comprehension. Hotel managers are complaining that they can no longer find enough English-speakers to act as receptionists. Departing tourists, polled at the airport, voice growing frustration at not being understood (The Economist 1/20/2001).

V. Evaluating Arguments

Q: What does it mean for an argument to be good? What are the different ways in which arguments can be good? Good arguments:

• Are persuasive.
• Have premises that provide good evidence for the conclusion.
• Contain premises that are true.
• Reach a true conclusion.
• Provide the audience good reasons for accepting the conclusion.

The focus of logic is primarily about one type of goodness: The logical relationship between premises and conclusion.

An argument is good in this sense if the premises provide good evidence for the conclusion. But what does it mean for premises to provide good evidence? We need some new concepts to capture this idea of premises providing good logical support. In order to do so, we will first need to distinguish between two types of argument.

VI. Two Types of Arguments

The two main types of arguments are called deductive and inductive arguments. We differentiate them in terms of the type of support that the premises are meant to provide for the conclusion.

Deductive Arguments are arguments in which the premises are meant to provide conclusive logical support for the conclusion.

1. All humans are mortal

2. Socrates is a human.

∴ Therefore, Socrates is mortal.

1. No student in this class will fail.

2. Mary is a student in this class.

∴ Therefore, Mary will not fail.

1. A intersects lines B and C.

2. Lines A and B form a 90-degree angle

3. Lines A and C form a 90-degree angle.

∴ B and C are parallel lines.

Inductive arguments are, by their very nature, risky arguments.

Arguments in which premises provide probable support for the conclusion.

Statistical Examples:

1. Ten percent of all customers in this restaurant order soda.

2. John is a customer.

∴ John will not order Soda..

1. Some students work on campus.

2. Bill is a student.

∴ Bill works on campus.

1. Vegas has the Carolina Panthers as a six-point favorite for the super bowl.

∴ Carolina will win the Super Bowl.

VII. Good Deductive Arguments

The First Type of Goodness: Premises play their function – they provide conclusive logical support.

Deductive and inductive arguments have different aims. Deductive argument attempt to provide conclusive support or reasons; inductive argument attempt to provide probable reasons or support. So we must evaluate these two types of arguments.

Deductive arguments attempt to be valid.

To put validity in another way: if the premises are true, then the conclusion must be true.

It is very important to note that validity has nothing to do with whether or not the premises are, in fact, true and whether or not the conclusion is in fact true; it merely has to do with a certain conditional claim. If the premises are true, then the conclusion must be true.

Q: What does this mean?

• The validity of an argument does not depend upon the actual world. Rather, it depends upon the world described by the premises.
• First, consider the world described by the premises. In this world, is it logically possible for the conclusion to be false? That is, can you even imagine a world in which the conclusion is false?

Reflection Questions:

• If you cannot, then why not?
• If you can, then provide an example of a valid argument.

You should convince yourself that validity is not just about the actual truth or falsity of the premises and conclusion. Rather, validity only has to do with a certain logical relationship between the truth of the premise and the truth of the conclusion. So the only possible combination that is ruled out by a valid argument is a set of true premises and false conclusion.

Let’s go back to example #1. Here are the premises:

1. All humans are mortal.

If both of these premises are true, then every human that we find must be a mortal. And this means, that it must be the case that if Socrates is a human, that Socrates is mortal.

Reflection Questions about Invalid Arguments:

• Can you have an invalid argument with a true premise?
• Can you have an invalid argument with true premises and a true conclusion?

The s econd type of goodness for deductive arguments: The premises provide us the right reasons to accept the conclusion.

Soundness V ersus V alidity:

Our original argument is a sound one:

∴ Socrates is mortal.

Question: Can a sound argument have a false conclusion?

VIII. From Deductive Arguments to Inductive Arguments

Question: What happens if we mix around the premises and conclusion?

2. Socrates is mortal.

∴ Socrates is a human.

1. Socrates is mortal

∴ All humans are mortal.

Are these valid deductive arguments?

NO, but they are common inductive arguments.

Other examples :

Suppose that there are two opaque glass jars with different color marbles in them.

1. All the marbles in jar #1 are blue.

2. This marble is blue.

∴ This marble came from jar #1.

1. This marble came from jar #2.

2. This marble is red.

∴ All the marbles in jar #2 are red.

While this is a very risky argument, what if we drew 100 marbles from jar #2 and found that they were all red? Would this affect the second argument’s validity?

IX. Inductive Arguments:

The aim of an inductive argument is different from the aim of deductive argument because the type of reasons we are trying to provide are different. Therefore, the function of the premises is different in deductive and inductive arguments. And again, we can split up goodness into two types when considering inductive arguments:

• The premises provide the right logical support.
• The premises provide the right type of reason.

Logical S upport:

Remember that for inductive arguments, the premises are intended to provide probable support for the conclusion. Thus, we shall begin by discussing a fairly rough, coarse-grained way of talking about probable support by introducing the notions of strong and weak inductive arguments.

A strong inductive argument:

• The vast majority of Europeans speak at least two languages.
• Sam is a European.

∴ Sam speaks two languages.

Weak inductive argument:

• This quarter is a fair coin.

∴ Therefore, the next coin flip will land heads.

• At least one dog in this town has rabies.
• Fido is a dog that lives in this town.

∴ Fido has rabies.

The R ight T ype of R easons. As we noted above, the right type of reasons are true statements. So what happens when we get an inductive argument that is good in the first sense (right type of logical support) and good in the second sense (the right type of reasons)? Corresponding to the notion of soundness for deductive arguments, we call inductive arguments that are good in both senses cogent arguments.

• With which of the following types of premises and conclusions can you have a strong inductive argument?
• With which of the following types of premises and conclusions can you have a cogent inductive argument?

X. Steps for Evaluating Arguments:

• Read a passage and assess whether or not it contains an argument.
• If it does contain an argument, then identify the conclusion and premises.
• If yes, then assess it for soundness.
• If not, then treat it as an inductive argument (step 3).
• If the inductive argument is strong, then is it cogent?

XI. Evaluating Real – World Arguments

An important part of evaluating arguments is not to represent the arguments of others in a deliberately weak way.

For example, suppose that I state the following:

All humans are mortal, so Socrates is mortal.

Is this valid? Not as it stands. But clearly, I believe that Socrates is a human being. Or I thought that was assumed in the conversation. That premise was clearly an implicit one.

So one of the things we can do in the evaluation of argument is to take an argument as it is stated, and represent it in a way such that it is a valid deductive argument or a strong inductive one. In doing so, we are making explicit what one would have to assume to provide a good argument (in the sense that the premises provide good – conclusive or probable – reason to accept the conclusion).

The teacher’s policy on extra credit was unfair because Sally was the only person to have a chance at receiving extra credit.

• Sally was the only person to have a chance at receiving extra credit.
• The teacher’s policy on extra credit is fair only if everyone gets a chance to receive extra credit.

Therefore, the teacher’s policy on extra credit was unfair.

Valid argument

Sally didn’t train very hard so she didn’t win the race.

• Sally didn’t train very hard.
• If you don’t train hard, you won’t win the race.

Therefore, Sally didn’t win the race.

Strong (not valid):

• If you won the race, you trained hard.
• Those who don’t train hard are likely not to win.

Therefore, Sally didn’t win.

Ordinary workers receive worker’s compensation benefits if they suffer an on-the-job injury. However, universities have no obligations to pay similar compensation to student athletes if they are hurt while playing sports. So, universities are not doing what they should.

• Ordinary workers receive worker’s compensation benefits if they suffer an on-the-job injury that prevents them working.
• Student athletes are just like ordinary workers except that their job is to play sports.
• So if student athletes are injured while playing sports, they should also be provided worker’s compensation benefits.
• Universities have no obligations to provide injured student athletes compensation.

Therefore, universities are not doing what they should.

Deductively valid argument

If Obama couldn’t implement a single-payer healthcare system in his first term as president, then the next president will not be able to implement a single-payer healthcare system.

• Obama couldn’t implement a single-payer healthcare system.
• In Obama’s first term as president, both the House and Senate were under Democratic control.
• The next president will either be dealing with the Republican-controlled house and senate or at best, a split legislature.
• Obama’s first term as president will be much easier than the next president’s term in terms of passing legislation.

Therefore, the next president will not be able to implement a single-payer healthcare system.

Strong inductive argument

Sam is weaker than John. Sam is slower than John. So Sam’s time on the obstacle will be slower than John’s.

• Sam is weaker than John.
• Sam is slower than John.
• A person’s strength and speed inversely correlate with their time on the obstacle course.

Therefore, Sam’s time will be slower than John’s.

XII. Diagramming Arguments

All the arguments we’ve dealt with – except for the last two – have been fairly simple in that the premises always provided direct support for the conclusion. But in many arguments, such as the last one, there are often arguments within arguments.

Obama example :

• The next president will either be dealing with the Republican controlled house and senate or at best, a split legislature.

∴ The next president will not be able to implement a single-payer healthcare system.

It’s clear that premises #2 and #3 are used in support of #4. And #1 in combination with #4 provides support for the conclusion.

When we diagram arguments, the aim is to represent the logical relationships between premises and conclusion. More specifically, we want to identify what each premise supports and how.

This represents that 2+3 together provide support for 4

This represents that 4+1 together provide support for 5

When we say that 2+3 together or 4+1 together support some statement, we mean that the logical support of these statements are dependent upon each other. Without the other, these statements would not provide evidence for the conclusion. In order to identify when statements are dependent upon one another, we simply underline the set that are logically dependent upon one another for their evidential support. Every argument has a single conclusion, which the premises support; therefore, every argument diagram should point to the conclusion (c).

Sam Example:

• Sam is less flexible than John.
• A person’s strength and flexibility inversely correlate with their time on the obstacle course.

∴ Therefore, Sam’s time will be slower than John’s.

In some cases, different sets of premises provide evidence for the conclusion independently of one another. In the argument above, there are two logically independent arguments for the conclusion that Sam’s time will be slower than John’s. That Sam is weaker than John and that being weaker correlates with a slower time provide evidence for the conclusion that Sam will be slower than John. Completely independent of this argument is the fact that Sam is less flexible and that being less flexible corresponds with a slower time. The diagram above represent these logical relations by showing that #1 and #3 dependently provide support for #4. Independent of that argument, #2 and #3 also dependently provide support for #4. Therefore, there are two logically independent sets of premises that provide support for the conclusion.

Try diagramming the following argument for yourself. The structure of the argument has been provided below:

• All humans are mortal
• Socrates is human
• So Socrates is mortal.
• If you feed a mortal person poison, he will die.

∴ Therefore, Socrates has been fed poison, so he will die.

• This section is taken from http://philosophy.hku.hk/think/ and is in use under creative commons license. Some modifications have been made to the original content. ↵

Critical Thinking Copyright © 2019 by Brian Kim is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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IDENTIFYING ARGUMENTS

8.1 WHAT IS AN ARGUMENT?

In ordinary usage, an argument is often taken to be a somewhat heated dispute between people. But in logic and critical thinking, an argument is a list of statements, one of which is the conclusion and the others are the premises or assumptions of the argument. An example:

It is raining.

So you should bring an umbrella.

In this argument, the first statement is the premise and the second one the conclusion. The premises of an argument are offered as reasons for accepting the conclusion. It is therefore irrational to accept an argument as a good one and yet refuse to accept the conclusion. Giving reasons is a central part of critical thinking. It is not the same as simply expressing an opinion. If you say “that dress looks nice,” you are only expressing an opinion. But if you say “that dress looks nice because the design is very elegant,” then it would be an argument indeed. Dogmatic people tend to make assertions without giving arguments. When they cannot defend themselves, they often resort to responses such as “this is a matter of opinion,” “this is just what you think,” or “I have the right to believe whatever I want.”

The ability to construct, identify, and evaluate arguments is a crucial part of critical thinking. Giving good arguments helps us convince other people, and improve our presentation and debating skills. More important, using arguments to support our beliefs with reasons is likely to help us discover the ...

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8.8: Differences Between Truth and Validity

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Differences Between Truth and Validity

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8 Arguments and Critical Thinking

J. anthony blair, introduction [1].

This chapter discusses two different conceptions of argument, and then discusses the role of arguments in critical thinking. It is followed by a chapter in which David Hitchcock carefully analyses one common concept of an argument.

1. Two meanings of ‘argument’

The word ‘argument’ is used in a great many ways. Any thorough understanding of arguments requires understanding ‘argument’ in each of its senses or uses. These may be divided into two large groupings: arguments had or engaged in , and arguments made or used . I begin with the former.

1.1 A n ‘a rgument’ as something two parties have with each othe r, something they get into, the kind of ‘argument’ one has in mind in de scribing two people as “arguing all the time ”

For many people outside academia or the practice of law, an argument is a quarrel . It is usually a verbal quarrel, but it doesn’t have to use words. If dishes are flying or people are glaring at each other in angry silence, it can still be an argument. What makes a quarrel an argument is that it involves a communication between two or more parties (however dysfunctional the communication may be) in which the parties disagree and in which that disagreement and reasons, actual or alleged, motivating it are expressed—usually in words or other communicative gestures.

Quarrels are emotional. The participants experience and express emotions, although that feature is not exclusive to arguments that are quarrels. People can and do argue emotionally, and (or) when inspired by strong emotions, when they are not quarrelling. Heated arguments are not necessarily quarrels; but quarrels tend to be heated.

What makes quarrels emotional in some cases is that at least one party experiences the disagreement as representing some sort of personal attack, and so experiences his or her ego or sense of self-worth as being threatened. Fear is a reaction to a perceived threat, and anger is a way of coping with fear and also with embarrassment and shame. In other cases, the argument about the ostensible disagreement is a reminder of or a pretext for airing another, deeper grievance. Jealousy and resentment fuel quarrels. Traces of ego-involvement often surface even in what are supposed to be more civilized argumentative exchanges, such as scholarly disputes. Quarrels tend not to be efficient ways of resolving the disagreements that gives rise to them because the subject of a disagreement changes as the emotional attacks escalate or because the quarrel was often not really about that ostensible disagreement in the first place.

In teaching that ‘argument’ has different senses, it is misleading to leave the impression (as many textbooks do) that quarrels are the only species of argument of this genus. In fact they are just one instance of a large class of arguments in this sense of extended, expressed, disagreements between or among two or more parties.

A dispute is an argument in this sense that need not be a quarrel. It is a disagreement between usually two parties about the legality, or morality, or the propriety on some other basis, of a particular act or policy. It can be engaged in a civil way by the disputants or their proxies (e.g., their spokespersons or their lawyers). Sometimes only the disputing parties settle their difference; sometimes a third party such as a mediator, arbitrator or judge is called in to impose a settlement.

A debate is another argument of this general kind. Debates are more or less formalized or regimented verbal exchanges between parties who might disagree, but in any case who take up opposing sides on an issue. Procedural rules that govern turn-taking, time available for each turn, and topics that may be addressed are agreed to when political opponents debate one another. Strict and precise rules of order govern who may speak, who must be addressed, sometimes time limits for interventions, in parliamentary or congressional debates in political decision-making bodies, or in formal intercollegiate competitive debates. Usually the “opponent” directly addressed in the debate is not the party that each speaker is trying to influence, so although the expressed goal is to “win” the debate, winning does not entail getting the opponent to concede. Instead, it calls for convincing an on-looking party or audience—the judge of the debate or the jury in a courtroom or the television audience or the press or the electorate as a whole—of the superior merits of one’s case for the opinion being argued for in the debate.

To be distinguished from a debate and a dispute by such factors as scale is a controversy . Think of such issues as the abortion controversy, the climate change controversy, the same-sex marriage controversy, the LGBT rights controversy, the animal rights controversy. The participants are many—often millions. The issues are complex and there are many disputes about details involved, including sometimes even formal debates between representatives of different sides. Typically there is a range of positions, and there might be several different sides each with positions that vary one from another. A controversy typically occurs over an extended period of time, often years and sometime decades long. But an entire controversy can be called an argument, as in, “the argument over climate change.” Controversies tend to be unregulated, unlike debates but like quarrels, although they need not be particularly angry even when they are emotional. Like quarrels, and unlike debates, the conditions under which controversies occur, including any constraints on them, are shaped by the participants.

Somewhere among quarrels, debates and controversies lie the theoretical arguments that theorists in academic disciplines engage in, in academic journals and scholarly monographs. In such arguments theorists take positions, sometimes siding with others and sometimes standing alone, and they argue back and forth about which theoretical position is the correct one. In a related type of argument, just two people argue back and forth about what is the correct position on some issue (including meta-level arguments about what is the correct way to frame the issue in the first place).

The stakes don’t have to be theories and the participants don’t have to be academics. Friends argue about which team will win the championship, where the best fishing spot is located, or what titles to select for the book club. Family members argue about how to spend their income, what school to send the children to, or whether a child is old enough to go on a date without a chaperone. Co-workers argue about the best way to do a job, whether to change service providers, whether to introduce a new product line, and so on. These arguments are usually amicable, whether or not they settle the question in dispute.

All of these kinds of “argument” in this sense of the term—quarrels, friendly disputes, arguments at work, professional arguments about theoretical positions, formal or informal debates, and various kinds of controversy—share several features.

• They involve communications between or among two or more people. Something initiates the communication, and either something ends it or there are ways for participants to join and to exit the conversation. They entail turn-taking (less or more regimented), each side addressing the other side and in turn construing and assessing what the other has to say in reply and formulating and communicating a response to the replies of the other side. And, obviously, they involve the expression, usually verbal, of theses and of reasons for them or against alternatives and criticisms.
• They have a telos or aim, although there seems to be no single end in mind for all of them or even for each of them. In a quarrel the goal might be to have one’s point of view prevail, to get one’s way, but it might instead (or in addition) be to humiliate the other person or to save one’s own self-respect. Some quarrels—think of the ongoing bickering between some long-married spouses—seem to be a way for two people to communicate, merely to acknowledge one another. In a debate, each side seeks to “win,” which can mean different things in different contexts ( cf. a collegiate debate vs. a debate between candidates in an election vs. a parliamentary debate). Some arguments seemed designed to convince the other to give up his position or accept the interlocutor’s position, or to get the other to act in some way or to adopt some policy. Some have the more modest goal of getting a new issue recognized for future deliberation and debate. Still others are clearly aimed not at changing anyone’s mind but at reinforcing or entrenching a point of view already held (as is usually the case with religious sermons or with political speeches to the party faithful). Some are intended to establish or to demonstrate the truth or reasonableness of some position or recommendation and (perhaps) also to get others to “see” that the truth has been established. Some seem designed to maintain disagreement, as when representatives of competing political parties argue with one another.
• All these various kinds of argument are more or less extended, both in the sense that they occur over time, sometimes long stretches of time, and also in the sense that they typically involved many steps: extensive and complex support for a point of view and critique of its alternatives.
• In nearly every case, the participants give reasons for the claims they make and they expect the other participants in the argument to give reasons for their claims. This is even a feature of quarrels, at least at the outset, although such arguments can deteriorate into name-calling and worse. (Notice that even the “yes you did; no I didn’t;…; did; didn’t” sequence of the Monty Python “Having an argument” skit breaks down and a reason is sought.)

The kinds of argument listed so far are all versions of having an argument (see Daniel J. O’Keefe, 1977, 1982). Some might think that this is not the sense of ‘argument’ that is pertinent to critical thinking instruction, but such arguments are the habitat of the kinds of argument that critical thinkers need to be able to identify, analyze and evaluate.

1.2 An argument a s something a person makes (or constructs, invents, borrows) consisting of purported reasons alleged to suggest, or support or prove a point and that is used for some purpose such as to persuade someone of some claim, to justify someone in maintaining the position claimed, or to test a claim .

When people have arguments—when they engage in one or another of the activities of arguing described above—one of the things they routinely do is present or allege or offer reasons in support of the claims that they advance, defend, challenge, dispute, question, or consider. That is, in having “arguments,” we typically make and use “arguments.” The latter obviously have to be arguments in different sense from the former. They are often called “reason-claim” complexes. If arguments that someone has had constitute a type of communication or communicative activity, arguments that someone has made or used are actual or potential contributions to such activities. Reason-claim complexes are typically made and used when engaged in an argument in the first sense, trying to convince someone of your point of view during a disagreement or dispute with them. Here is a list of some of the many definitions found in textbooks of ‘argument’ in this second sense.

“… here [the word ‘argument’] … is used in the … logical sense of giving reasons for or against some claim.” Understanding Arguments, Robert Fogelin and Walter Sinnott-Armstrong, 6th ed., p. 1. “Thus an argument is a discourse that contains at least two statements, one of which is asserted to be a reason for the other.” Monroe Beardsley, Practical Logic, p. 9. “An argument is a set of claims a person puts forward in an attempt to show that some further claim is rationally acceptable.” Trudy Govier. A Practical Study of Arguments, 5th ed., p. 3. An argument is “a set of clams some of which are presented as reasons for accepting some further claim.” Alec Fisher, Critical Thinking, An Introduction, p. 235. Argument: “A conclusion about an issue that is supported by reasons.” Sherry Diestler, Becoming a Critical Thinker, 4th ed., p. 403. “ Argument: An attempt to support a conclusion by giving reasons for it.” Robert Ennis, Critical Thinking, p. 396. “Argument – A form of thinking in which certain statements (reasons) are offered in support of another statement (conclusion).” John Chaffee, Thinking Critically, p. 415 “When we use the word argument in this book we mean a message which attempts to establish a statement as true or worthy of belief on the basis of other statements.” James B. Freeman, Thinking Logically, p. 20 “Argument. A sequence of propositions intended to establish the truth of one of the propositions.” Richard Feldman, Reason and Argument, p. 447. “Arguments consist of conclusions and reasons for them, called ‘premises’.” Wayne Grennan, Argument Evaluation, p. 5. Argument: “A set of claims, one of which, the conclusion is supported by [i.e., is supposed to provide a reason for] one or more of the other claims. Reason in the Balance, Sharon Bailin & Mark Battersby, p. 41.

These are not all compatible, and most of them define ‘argument’ using other terms—‘reasons’, ‘claims’, ‘propositions’, ‘statements’, ‘premises’ and ‘conclusions’—that are in no less need of definition than it is. In the next chapter, David Hitchcock offers a careful analysis of this concept of an argument.

Some define argument in this second sense as a kind of communication; others conceive it as a kind of set of propositions that can serve communicative functions, but others as well (such as inquiry). Either way, the communicative character, or function, of arguments has been the subject of much of the research in the past several decades. Most recently what some have called “multi-modal” argument has attracted attention, focusing on the various ways arguments can be communicated, especially visually or in a mix of verbal and visual modes of communication. Some have contended that smells and sounds can play roles in argument communication as well. This area of research interest would seem to have relevance for the analysis of arguments on the web.

1.3 Argumentation

‘Argumentation’ is another slippery term. It is used in several different senses.

Sometimes it is used to mean the communicative activity in which arguments are exchanged: “During their argumentation they took turns advancing their own arguments and criticizing one another’s arguments.” Sometimes ‘argumentation’ denotes the body of arguments used in an argumentative exchange: “The evening’s argumentation was of high quality.” And occasionally you will find it used to refer to the reasons or premises supporting a conclusion, as in: “The argumentation provided weak support for the thesis.” ‘Argumentation theory’ is the term often used to denote theory about the nature of arguments and their uses, including their uses in communications involving exchanges of arguments.

2 The relation between critical thinking and argument

2 .1 arguments are both tools of critical thinking and objects of critical thinking.

In … [one] sense, thought denotes belief resting upon some basis, that is, real or supposed knowledge going beyond what is directly present. … Some beliefs are accepted when their grounds have not themselves been considered …. … such thoughts may mean a supposition accepted without reference to its real grounds. These may be adequate, they may not; but their value with reference to the support they afford the belief has not been considered. Such thoughts grow up unconsciously and without reference to the attainment of correct belief. They are picked up—we know not how. From obscure sources and by unnoticed channels they insinuate themselves into acceptance and become unconsciously a part of our mental furniture. Tradition, instruction, imitation—all of which depend upon authority in some form, or appeal to our advantage, or fall in with strong passions—are responsible for them. Such thoughts are prejudices, that is, prejudgments, not judgments proper that rest upon a survey of evidence. (John Dewey, How We Think , pp. 4-5, emphasis added.)

People—all of us—routinely adopt beliefs and attitudes that are prejudices in Dewey’s sense of being prejudgments, “not judgments proper that rest upon a survey of evidence.” One goal of critical thinking education is to provide our students with the means to be able, when it really matters, to “properly survey” the grounds for beliefs and attitudes.

Arguments supply one such means. The grounds for beliefs and attitudes are often expressed, or expressible, as arguments for them. And the “proper survey” of these arguments is to test them by subjecting them to the critical scrutiny of counter-arguments.

Arguments also come into play when the issue is not what to believe about a contentious issue, but in order just to understand the competing positions. Not only are we not entitled to reject a claim to our belief if we cannot counter the arguments that support it; we are not in possession of an understanding of that claim if we cannot formulate the arguments that support it to the satisfaction of its proponents.

Furthermore, arguments can be used to investigate a candidate for belief by those trying “to make up their own minds” about it. The investigator tries to find and express the most compelling arguments for and against the candidate. Which arguments count as “most compelling” are the ones that survive vigorous attempts, using arguments, to refute or undermine them. These survivors are then compared against one another, the pros weighed against the cons. More arguments come into play in assessing the attributed weights.

In these ways, a facility with arguments serves a critical thinker well. Such a facility includes skill in recognizing, interpreting and evaluating arguments, as well as in formulating them. That includes skill in laying out complex arguments, in recognizing argument strengths and weaknesses, and in making a case for one’s critique. It includes the ability to distinguish the more relevant evidence from the less, and to discriminate between minor, fixable flaws and major, serious problems, in arguments. Thus the critical thinker is at once adept at using arguments in various ways and at the same time sensitive in judging arguments’ merits, applying the appropriate criteria.

Moreover, arguments in the sense of “reasons-claim” complexes surround us in our daily lives. Our “familiars”, as Gilbert (2014) has dubbed them—our family members, the friends we see regularly, shopkeepers and others whose services we patronize daily, our co-workers—engage us constantly in argumentative discussions in which they invoke arguments to try to get us to do things, to agree, to judge, to believe. The public sphere—the worlds of politics, commerce, entertainment, leisure activities, social media (see Jackson’s chapter)—is another domain in which arguments can be found, although (arguably) mere assertion predominates there. In the various roles we play as we go through life—child, parent, spouse or partner, student, worker, patient, subordinate or supervisor, citizen (voter, jurist, community member), observer or participant, etc.—we are invited with arguments to agree or disagree, approve or disapprove, seek or avoid. We see others arguing with one another and are invited to judge the merits of the cases they make. Some of these arguments are cogent and their conclusions merit our assent, but others are not and we should not be influenced by them. Yet others are suggestive and deserve further thought.

We can simply ignore many of these arguments, but others confront us and force us to decide whether or not to accept them. Often it is unclear whether someone has argued or done something else: just vented, perhaps, or explained rather than argued, or merely expressed an opinion without arguing for it, or was confused. So we initially might have to decide whether there is an argument that we need to deal with. When it is an argument, often in order to make up our minds about it we need first to get clear about exactly what the argument consists of. So even before we evaluate this argument we have to identify and analyze it. (These operations are discussed in Chapter 12.)

In the end we have to decide for ourselves whether the argument makes its case or falls short. Does the conclusion really follow from the premises? Is there enough evidence to justify the conclusion? Is it the right kind of evidence? Are there well-known objections or arguments against the conclusion that haven’t been acknowledged and need to be answered satisfactorily? Can they be answered? And are the premises themselves believable or otherwise acceptable? Are there other arguments, as good or better, that support the claim?

Critical thinking can (and should!) come into all of these decisions we need to make in the identification, the analysis and the assessment of arguments.

2 .2  Critical thinking about things other than arguments

Many critical thinking textbooks focus exclusively on the analysis and evaluation of arguments. While the centrality of arguments to the art of critical thinking is unquestionable, a strong case can be made that critical thinking has other objectives in addition to appreciating arguments. In their analysis of the concept of critical thinking, Fisher and Scriven suggest the following definition:

Critical thinking is skilled and active interpretation and evaluation of o b servations and communications , information and argumentation. (1997, p. 21, emphasis added)

We agree with the gist of this claim, but notice what Fisher and Scriven propose as the objects to which critical thinking applies. Not just argumentation, but as well observations, communications and information. About observations, they note that:

What one sees (hears, etc.) are usually things and happenings, and one often has to interpret what one sees, sometimes calling on critical thinking skills to do so, most obviously in cases where the context involves weak lighting, strong emotions, possible drug effects, or putatively magical or parapsychological phenomena. Only after the application of critical thinking—and sometimes not even then—does one know what one “really saw”. … When the filter of critical thinking has been applied to the observations, and only then, one can start reasoning towards further conclusions using these observations as premises. ( Ibid ., p, 37)

An example is the recent large number of convictions in the U.S.A. that originally relied on eyewitness testimony but that have been overturned on the basis of DNA evidence. [2] ,  [3]

The DNA evidence proved that the accused was not the culprit, so the moral certainty of the eyewitness had to have been mistaken. The observation of the eyewitness was flawed. He or she did not think critically about whether the conditions need ed to make a reliable o b servation were present (e.g., were strong emotions like fear involved? was the lighting good? has he or she ordinarily a good memory for faces? was there time to observe carefully? were there distractions present?). Neither, probably, did the lawyers on either side, or else they immorally suppressed what should have been their doubts. As a consequence, innocent people languished in jail for years and guilty parties went free.

Communications are another object for critical thought. When in reply to Harry’s question, “How are you doing?” Morgan says, in a clipped and dull voice and a strained expression on her face, “I’m fine”, Harry needs to be aware that “How are you doing?” often functions as equivalent to a simple greeting, like “Hi” and so the response “Fine” could similarly be functioning as a polite return of the greeting, like “Hi back to you”, and not as an accurate report of the speaker’s condition. Harry needs to notice and interpret other aspects of Morgan’s communication—her lethargic tone of voice and her anxious facial expression—and to recognize the incompatibility between those signals and the interpretation of her response as an accurate depiction of Morgan’s state of well-being. He needs to employ critical interpretive skills to realize that Morgan has communicated that she is not fine at all, but for some reason isn’t offering to talk about it.

If President Trump did in fact say to his then F.B.I. director James Comey, about the F.B.I. investigation of former National Security Advisor Michaell Flynn “I hope you can let this go”, was it legitimate for Comey to interpret the President’s comment as a directive? And was Comey’s response, which was simply to ignore President Trump’s alleged comment, an appropriate response? What was going on? It takes critical thinking to try to sort out these issues. Taking the President’s alleged comment literally, it just expresses his attitude towards the FBI investigation of Flynn. But communications from the President in a tête-à-tête in the White House with the Director of the FBI are not occasions for just sharing attitudes. This was not an occasion on which they could step out of their political roles and chat person-to-person. The President can legitimately be presumed to be communicating his wishes as to what his FBI Director should do, and such expressions of wishes are, in this context, to be normally understood as directives. On the other hand, for the President to direct that an ongoing investigation by the FBI be stopped, or that it come up with a pre-determined finding, is illegal: it’s obstruction of justice. So Comey seemed faced with at least two possible interpretations of what he took the President to be saying: either an out-of-place expression of his attitude towards the outcome of the Flynn investigation or an illegal directive. Which was the President’s intention? However, there are other possibilities.

Was President Trump a political tyro whose lack of political experience might have left him ignorant of the fact that the FBI Director has to keep investigations free of political interference? Or might Trump have thought that the Presidency conveys the authority to influence the outcome of criminal investigations? Or might President Trump have been testing Mr. Comey to see if he could be manipulated? And Mr. Comey could have responded differently. He could have said, “I wish we could let this go too, Mr. President, but there are questions about General Flynn’s conduct that have to be investigated, and as you know, we cannot interfere with an ongoing FBI investigation”. Such a response would have forced the President to take back what he allegedly said, withdrawing any suggestion that his comment was a directive, or else to make it plain that he was indeed directing Comey to obstruct justice. In the event, apparently Mr. Comey did not take this way out, which would at once have displayed loyalty to the President (by protecting him from explicitly obstructing justice) and also have affirmed the independence of the FBI from interference from the White House. Perhaps he thought that the President clearly had directed him to obstruct justice, and judged that giving him an opportunity explicitly to withdraw that directive amounted to overlooking that illegal act, which would be a violation of his responsibilities as Director of the FBI. If so, however, simply not responding to the President’s comment, the path Comey apparently chose, also amounted to turning a blind eye to what he judged to be President Trump’s illegal directive.

As these two examples illustrate, the interpretation of communications, and the appropriate response to them can require critical thinking: recognizing different functions of communication, and being sensitive to the implications of different contexts of communication; being sensitive to the roles communicators occupy and to the rights, obligations, and limits attached to such roles.

As Fisher and Scriven acknowledge, “defining information is itself a difficult task.” They make a useful start by distinguishing information from raw data (“the numbers or bare descriptions obtained from measurements or observations”, op . cit., p. 41). No critical thinking is required for the latter; just the pains necessary to record raw data accurately, In many cases, though, the interpretation of raw data, the meaning or significance that they are said to have, can require critical thinking.

One might go beyond Fisher and Scriven’s list of other things besides arguments to which critical thinking can be applied. A thoughtful appreciation of novels or movies, plays or poetry, paintings or sculptures requires skilled interpretation, imagining alternatives, thoughtful selection of appropriate criteria of evaluation and then the selection and application of appropriate standards, and more. A good interior designer must consider the effects and interactions of space and light and color and fabrics and furniture design, and coordinate these with clients’ lifestyles, habits and preferences. Advanced practical skills in various sciences come into play. A coach of a sports team must think about each individual team member’s skills and deficiencies, personality and life situation; about plays and strategies, opponents’ skills sets; approaches to games; and much more. Conventional approaches need to be reviewed as to their applicability to the current situation. Alternative possibilities need to be creatively imagined and critically assessed. And all of this is time-sensitive, sometimes calling for split-second decisions. The thinking involved in carrying out the tasks of composing a review of some work of literature or art or of coaching a sports team can be routine and conventional, or it can be imaginative, invoking different perspectives and challenging standard criteria.

The list could go on. The present point is that, while argument is central to critical thinking, critical thinking about and using arguments is not all there is to critical thinking. [4]

Bailin, Sharon & Battersby, Mark. (2010). Reason in the Balance , An I n quiry Approach to Critical Thinking , 1 st ed. Toronto: McGraw-Hill Ryerson.

Beardsley, Monroe C. (1950). Practical L ogic . Englewood Cliffs, NJ: Prentice-Hall.

Chaffee, John. 1985. Thinking Critically . Boston: Houghton Mifflin.

Dewey, John. (1910, 1991). How We Think . Lexington, MAD.C. Heath; Buffalo, NY: Prometheus Books.

Diestler, Sherry. (2005). Becoming a Critical Thinker , 4 th ed. Upper Saddle River, NJ: Pearson Education.

Ennis, Robert H. (1996). Critical Thinking . Upper Saddle River, NJ: Prentice-Hall.

Feldman, Richard. (1993). Reason and Argument , 2 nd ed. Upper Saddle River, NJ: Prentice-Hall.

Fisher, Alex.(2001). Critical Thinking, An Introduction . Cambridge: Cambridge University Press.

Fisher, Alec & Scriven, Michael. (1997). Critical Thinking, Its Definition and Assessment . Point

Reyes, CA: EdgePress; Norwich, UK: Center for Research in Critical Thinking.

Fogelin, Robert & Sinnott-Armstrong, Walter. (2001). Understanding A r guments , An Introduction to Informal Logic , 6 th ed. Belmont, CA: Wadsworth.

Freeman, James B. (1988.) Thinking Logically , Basic Concepts of Reaso n ing . Englewood Cliffs, NJ: Prentice-Hall.

Grennan, Wayne . (1984). Argument Evaluation . Lanham, MD: University Press of America.

Govier, Trudy. (2001). A Practical Study of Argument , 5 th ed. Belmont, CA: Wadsworth.

O’Keefe, Daniel J. (1977). Two concepts of argument. Journal of the Amer i can Forensic Association , 13 , 121-128.

O‘Keefe, Daniel J. (1982). The concepts of argument and arguing. In J. R. Cox & C. A. Willard (Eds.), Advances in Argumentation Theory and R e search , pp. 3-23. Carbondale, IL: Southern Illinois University Press.

• © J. Anthony Blair ↵
• According to the Innocence Project, “Eyewitness misidentification is the greatest contributing factor to wrongful convictions proven by DNA testing, playing a role in more than 70% of convictions [in the U.S.A.] overturned through DNA testing nationwide.” (https://www.innocenceproject.org/causes/eyewitness-misidentification/, viewed August 2017). ↵
• I owe the general organization and many of the specific ideas of this chapter to a series of lectures by Jean Goodwin at the Summer Institute on Argumentation sponsored by the Centre for Research in Reasoning, Argumentation and Rhetoric at the University of Windsor. ↵

Studies in Critical Thinking Copyright © by J. Anthony Blair is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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M18 Critical Thinking & Reasoning

Critical thinking and reasoning: logic and the role of arguments.

Critical thinkers tend to exhibit certain traits that are common to them. These traits are summarized in Table 6.1: [1]

Recall that critical thinking is an active mode of thinking. Instead of just receiving messages and accepting them as is, we consider what they are saying. We ask if messages are well-supported. We determine if their logic is sound or slightly flawed. In other words, we act on the messages before we take action based on them. When we enact critical thinking on a message, we engage a variety of skills including: listening, analysis, evaluation, inference and interpretation or explanation, and self-regulation [2]

Next, we will examine each of these skills and their role in critical thinking in greater detail. As you read through the explanation of and examples for each skill, think about how it works in conjunction with the others. It’s important to note that while our discussion of the skills is presented in a linear manner, in practice our use of each skill is not so straightforward. We may exercise different skills simultaneously or jump forward and backward.

“ Martha Stewart ” by nrkbeta.  CC-BY-SA .

Without an open-minded mind, you can never be a great success. ~ Martha Stewart

In order to understand listening, we must first understand the difference between listening and hearing . At its most basic, hearing refers to the physiological process of receiving sounds, while listening refers to the  psychological process of interpreting or making sense of those sounds.

Every minute of every day we are surrounded by hundreds of different noises and sounds. If we were to try to make sense of each different sound we would probably spend our day just doing this. While we may hear all of the noises, we filter out many of them. They pass through our lives without further notice. Certain noises, however, jump to the forefront of our consciousness. As we listen to them, we make sense of these sounds. We do this every day without necessarily thinking about the process. Like many other bodily functions, it happens without our willing it to happen.

Critical thinking requires that we consciously listen to messages. We must focus on what is being said – and not said. We must strive not to be distracted by other outside noises or the internal noise of our own preconceived ideas. For the moment we only need to take in the message.

Listening becomes especially difficult when the message contains highly charged information. Think about what happens when you try to discuss a controversial issue such as abortion. As the other person speaks, you may have every good intention of listening to the entire argument.

However, when the person says something you feel strongly about you start formulating a counter-argument in your head. The end result is that both sides end up talking past each other without ever really listening to what the other says.

Once we have listened to a message, we can begin to analyze it. In practice we often begin analyzing messages while still listening to them. When we analyze something, we consider it in greater detail, separating out the main components of the message. In a sense, we are acting like a surgeon on the message, carving out all of the different elements and laying them out for further consideration and possible action.

Let’s return to Shonda’s persuasive speech to see analysis in action. As part of the needs section of her speech, Shonda makes the following remarks:

Americans today are some of the unhealthiest people on Earth. It seems like not a week goes by without some news story relating how we are the fattest country in the world. In addition to being overweight, we suffer from a number of other health problems. When I was conducting research for my speech, I read somewhere that heart attacks are the number one killer of men and the number two killer of women. Think about that. My uncle had a heart attack and had to be rushed to the hospital. They hooked him up to a bunch of different machines to keep him alive. We all thought he was going to die. He’s ok now, but he has to take a bunch of pills every day and eat a special diet. Plus he had to pay thousands of dollars in medical bills. Wouldn’t you like to know how to prevent this from happening to you?

If we were to analyze this part of Shonda’s speech (see Table 6.2), we could begin by looking at the claims she makes. We could then look at the evidence she presents in support of these claims. Having parsed out the various elements, we are then ready to evaluate them and by extension the message as a whole.

When we evaluate something we continue the process of analysis by assessing the various claims and arguments for validity. One way we evaluate a message is to ask questions about what is being said and who is saying it. The following is a list of typical questions we may ask, along with an evaluation of the ideas in Shonda’s speech.

Is the speaker credible?

Yes. While Shonda may not be an expert per se on the issue of health benefits related to wine, she has made herself a mini-expert through conducting research.

Does the statement ring true or false based on common sense?

It sounds kind of fishy. Four or more glasses of wine in one sitting doesn’t seem right. In fact, it seems like it might be bordering on binge drinking.

Does the logic employed hold up to scrutiny?

Based on the little bit of Shonda’s speech we see here, her logic does seem to be sound. As we will see later on, she actually commits a few fallacies.

What questions or objections are raised by the message?

In addition to the possibility of Shonda’s proposal being binge drinking, it also raises the possibility of creating alcoholism or causing other long term health problems.

How will further information affect the message?

More information will probably contradict her claims. In fact, most medical research in this area contradicts the claim that drinking 4 or more glasses of wine a day is a good thing.

Will further information strengthen or weaken the claims?

Most likely Shonda’s claims will be weakened.

What questions or objections are raised by the claims?

In addition to the objections we’ve already discussed, there is also the problem of the credibility of Shonda’s expert “doctor.”

A wise man proportions his belief to the evidence. ~ David Hume

Inference and Interpretation or Explanation

“Imply” or “Infer”?

For two relatively small words, imply and infer seem to generate an inordinately large amount of confusion. Understanding the difference between the two and knowing when to use the right one is not only a useful skill, but it also makes you sound a lot smarter!

Let’s begin with imply. Imply means to suggest or convey an idea. A speaker or a piece of writing implies things. For example, in Shonda’s speech, she implies it is better to drink more red wine. In other words, she never directly says that we need to drink more red wine, but she clearly hints at it when she suggests that drinking four or more glasses a day will provide us with health benefits.

Now let’s consider infer. Infer means that something in a speaker’s words or a piece of writing helps us to draw a conclusion outside of his/her words. We infer a conclusion. Returning to Shonda’s speech, we can infer she would want us to drink more red wine rather than less. She never comes right out and says this. However, by considering her overall message, we can draw this conclusion.

Another way to think of the difference between imply and infer is: A speaker (or writer for that matter) implies. The audience infers.

Therefore, it would be incorrect to say that Shonda infers we should drink more rather than less wine. She implies this. To help you differentiate between the two, remember that an inference is something that comes from outside the spoken or written text.

The next step in critically examining a message is to interpret or explain the conclusions that we draw from it. At this phase we consider the evidence and the claims together. In effect we are reassembling the components that we parsed out during analysis. We are continuing our evaluation by looking at the evidence, alternatives, and possible conclusions.

Before we draw any inferences or attempt any explanations, we should look at the evidence provided. When we consider evidence we must first determine what, if any, kind of support is provided. Of the evidence we then ask:

• Is the evidence sound?
• Does the evidence say what thespeaker says it does?
• Does contradictory evidenceexist?
• Is the evidence from a validcredible source?

Seatbelt by M.Minderhoud, CC-BY-SA .

Even though these are set up as yes or no questions, you’ll probably find in practice that your answers are a bit more complex. For example, let’s say you’re writing a speech on why we should wear our seatbelts at all times while driving. You’ve researched the topic and found solid, credible information setting forth the numerous reasons why wearing a seatbelt can help save your life and decrease the number of injuries experienced during a motor vehicle accident. Certainly, there exists contradictory evidence arguing seat belts can cause more injuries. For example, if you’re in an accident where your car is partially submerged in water, wearing a seatbelt may impede your ability to quickly exit the vehicle. Does the fact that this evidence exists negate your claims? Probably not, but you need to be thorough in evaluating and considering how you use your evidence.

A man who does not think for himself does not think at all. ~ Oscar Wilde

Self-Regulation

The final step in critically examining a message is actually a skill we should exercise throughout the entire process. With self-regulation, we consider our pre-existing thoughts on the subject and any biases we may have. We examine how what we think on an issue may have influenced the way we understand (or think we understand) the message and any conclusions we have drawn. Just as contradictory evidence doesn’t automatically negate our claims or invalidate our arguments, our biases don’t necessarily make our conclusions wrong. The goal of practicing self-regulation is not to disavow or deny our opinions. The goal is to create distance between our opinions and the messages we evaluate.

Man thinking on bus , by IG8. CC-BY .

The Value of Critical Thinking

In public speaking, the value of being a critical thinker cannot be overstressed. Critical thinking helps us to determine the truth or validity of arguments. However, it also helps us to formulate strong arguments for our speeches. Exercising critical thinking at all steps of the speech writing and delivering process can help us avoid situations like Shonda found herself in. Critical thinking is not a magical panacea that will make us super speakers. However, it is another tool that we can add to our speech toolbox.

As we will learn in the following pages, we construct arguments based on logic. Understanding the ways logic can be used and possibly misused is a vital skill. To help stress the importance of it, the Foundation for Critical Thinking has set forth universal standards of reasoning. These standards can be found in Table 6.3.

When the mind is thinking, it is talking to itself. ~ Plato

Logic and the Role of Arguments

“Sharia Law Billboard” by Matt57. Public domain.

We use logic every day. Even if we have never formally studied logical reasoning and fallacies, we can often tell when a person’s statement doesn’t sound right. Think about the claims we see in many advertisements today—Buy product X, and you will be beautiful/thin/happy or have the carefree life depicted in the advertisement. With very little critical thought, we know intuitively that simply buying a product will not magically change our lives. Even if we can’t identify the specific fallacy at work in the argument (non causa in this case), we know there is some flaw in the argument.

By studying logic and fallacies we can learn to formulate stronger and more cohesive arguments, avoiding problems like that mentioned above. The study of logic has a long history. We can trace the roots of modern logical study back to Aristotle in ancient Greece. Aristotle’s simple definition of logic as the means by which we come to know anything still provides a concise understanding of logic. [3] Of the classical pillars of a core liberal arts education of logic, grammar, and rhetoric, logic has developed as a fairly independent branch of philosophical studies. We use logic everyday when we construct statements, argue our point of view, and in myriad other ways. Understanding how logic is used will help us communicate more efficiently and effectively.

Defining Arguments

When we think and speak logically, we pull together statements that combine reasoning with evidence to support an assertion, arguments. A logical argument should not be confused with the type of argument you have with your sister or brother or any other person. When you argue with your sibling, you participate in a conflict in which you disagree about something. You may, however, use a logical argument in the midst of the argument with your sibling. Consider this example:

“Man and Woman Arguing” by mzacha. morgueFile .

Brother and sister, Sydney and Harrison are arguing about whose turn it is to clean their bathroom. Harrison tells Sydney she should do it because she is a girl and girls are better at cleaning. Sydney responds that being a girl has nothing to do with whose turn it is. She reminds Harrison that according to their work chart, they are responsible for cleaning the bathroom on alternate weeks. She tells him she cleaned the bathroom last week; therefore, it is his turn this week. Harrison, still unconvinced, refuses to take responsibility for the chore. Sydney then points to the work chart and shows him where it specifically says it is his turn this week. Defeated, Harrison digs out the cleaning supplies.

Throughout their bathroom argument, both Harrison and Sydney use logical arguments to advance their point. You may ask why Sydney is successful and Harrison is not. This is a good question. Let’s critically think about each of their arguments to see why one fails and one succeeds.

Let’s start with Harrison’s argument. We can summarize it into three points:

• Girls are better at cleaning bathrooms than boys.
• Sydney is a girl.
• Therefore, Sydney should clean the bathroom.

Harrison’s argument here is a form of deductive reasoning, specifically a syllogism. We will consider syllogisms in a few minutes. For our purposes here, let’s just focus on why Harrison’s argument fails to persuade Sydney. Assuming for the moment that we agree with Harrison’s first two premises, then it would seem that his argument makes sense. We know that Sydney is a girl, so the second premise is true. This leaves the first premise that girls are better at cleaning bathrooms than boys. This is the exact point where Harrison’s argument goes astray. The only way his entire argument will work is if we agree with the assumption girls are better at cleaning bathrooms than boys.

Let’s now look at Sydney’s argument and why it works. Her argument can be summarized as follows:

1. The bathroom responsibilities alternate weekly according to the work chart.

2. Sydney cleaned the bathroom last week.

3. The chart indicates it is Harrison’s turn to clean the bathroom this week.

4. Therefore, Harrison should clean the bathroom.

“Decorative toilet seat” by Bartux~commonswikiv. Public domain.

Sydney’s argument here is a form of inductive reasoning. We will look at inductive reasoning in depth below. For now, let’s look at why Sydney’s argument succeeds where Harrison’s fails. Unlike Harrison’s argument, which rests on assumption for its truth claims, Sydney’s argument rests on evidence. We can define evidence as anything used to support the validity of an assertion. Evidence includes: testimony, scientific findings, statistics, physical objects, and many others. Sydney uses two primary pieces of evidence: the work chart and her statement that she cleaned the bathroom last week. Because Harrison has no contradictory evidence, he can’t logically refute Sydney’s assertion and is therefore stuck with scrubbing the toilet.

Defining Deduction

Deductive reasoning refers to an argument in which the truth of its premises guarantees the truth of its conclusions. Think back to Harrison’s argument for Sydney cleaning the bathroom. In order for his final claim to be valid, we must accept the truth of his claims that girls are better at cleaning bathrooms than boys. The key focus in deductive arguments is that it must be impossible for the premises to be true and the conclusion to be false. The classic example is:

All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

We can look at each of these statements individually and see each is true in its own right. It is virtually impossible for the first two propositions to be true and the conclusion to be false. Any argument which fails to meet this standard commits a logical error or fallacy. Even if we might accept the arguments as good and the conclusion as possible, the argument fails as a form of deductive reasoning.

A few observations and much reasoning lead to error; many observations and a little reasoning to truth. ~ Alexis Carrel

Another way to think of deductive reasoning is to think of it as moving from a general premise to a specific premise. The basic line of reasoning looks like this:

“Deductive Reasoning” CC-BY-NC-ND .

This form of deductive reasoning is called a syllogism. A syllogism need not have only three components to its argument, but it must have at least three. We have Aristotle to thank for identifying the syllogism and making the study of logic much easier. The focus on syllogisms dominated the field of philosophy for thousands of years. In fact, it wasn’t until the early nineteenth century that we began to see the discussion of other types of logic and other forms of logical reasoning.

It is easy to fall prey to missteps in reasoning when we focus on syllogisms and deductive reasoning. Let’s return to Harrison’s argument and see what happens.

Logic: the art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding. ~ Ambrose Bierce

“Applied Deductive Reasoning” CC-BY-NC-ND .

Considered in this manner, it should be clear how the strength of the conclusion depends upon us accepting as true the first two statements. This need for truth sets up deductive reasoning as a very rigid form of reasoning. If either one of the first two premises isn’t true, then the entire argument fails.

Let’s turn to recent world events for another example.

“US Invasion Deductive Reasoning Example” CC-BY-NC-ND .

In the debates over whether the United States should take military action in Iraq, this was the basic line of reasoning used to justify an invasion. This logic was sufficient for the United States to invade Iraq; however, as we have since learned, this line of reasoning also shows how quickly logic can go bad. We subsequently learned that the “experts” weren’t quite so confident, and their “evidence” wasn’t quite as concrete as originally represented.

Defining Induction

Inductive reasoning is often though of as the opposite of deductive reasoning; however, this approach is not wholly accurate. Inductive reasoning does move from the specific to the general. However, this fact alone does not make it the opposite of deductive reasoning. An argument which fails in its deductive reasoning may still stand inductively.

Unlike deductive reasoning, there is no standard format inductive arguments must take, making them more flexible. We can define an inductive argument as one in which the truth of its propositions lends support to the conclusion. The difference here in deduction is the truth of the propositions establishes with absolute certainty the truth of the conclusion. When we analyze an inductive argument, we do not focus on the truth of its premises. Instead we analyze inductive arguments for their strength or soundness.

“Inductive Reasoning Model” CC-BY-NC-ND .

Another significant difference between deduction and induction is inductive arguments do not have a standard format. Let’s return to Sydney’s argument to see how induction develops in action:

• Bathroom cleaning responsibilities alternate weekly according to the work chart.
• Sydney cleaned the bathroom last week.
• The chart indicates it is Harrison’s turn to clean the bathroom this week.
• Therefore, Harrison should clean the bathroom.

What Sydney does here is build to her conclusion that Harrison should clean the bathroom. She begins by stating the general house rule of alternate weeks for cleaning. She then adds in evidence before concluding her argument. While her argument is strong, we don’t know if it is true. There could be other factors Sydney has left out. Sydney may have agreed to take Harrison’s week of bathroom cleaning in exchange for him doing another one of her chores. Or there may be some extenuating circumstances preventing Harrison from bathroom cleaning this week.

You should carefully study the Art of Reasoning, as it is what most people are very deficient in, and I know few things more disagreeable than to argue, or even converse with a man who has no idea of inductive and deductive philosophy. ~ William John Wills

Let’s return to the world stage for another example. After the 9/11 attacks on the World Trade Center, we heard variations of the following arguments:

• The terrorists were Muslim (or Arab or Middle Eastern)
• The terrorists hated America.
• Therefore, all Muslims (or Arabs or Middle Easterners) hate America.

“1993 Word Trade Center bombing” by Bureau of ATF 1993 Explosives Incident Report. Public domain.

Clearly, we can see the problem in this line of reasoning. Beyond being a scary example of hyperbolic rhetoric, we can all probably think of at least one counter example to disprove the conclusion. However, individual passions and biases caused many otherwise rational people to say these things in the weeks following the attacks. This example also clearly illustrates how easy it is to get tripped up in your use of logic and the importance of practicing self-regulation.

• Adapted from Facione, P. A. (1990). Critical Thinking: A Statement of Expert Consensus for Purposes of Educational Assessment and Instruction, The Delphi Report (Executive Summary) . Millbrae, CA: California Academic Press. ↵
• Adapted from Facione, P. A. (1990). ↵
• Aristotle. (1989). Prior Analytics (Trans. Robin Smith). Cambridge, MA: Hackett Publishing. ↵
• Image of man and woman arguing. Authored by : mzacha. Provided by : MorgueFile. Located at : http://mrg.bz/ynkIUa . License : All Rights Reserved . License Terms : Free to remix, commercial use, no attribution required. http://www.morguefile.com/license/morguefile
• Chapter 6 Logic and the Role of Arguments. Authored by : Terri Russ, J.D., Ph.D.. Provided by : Saint Mary's College, Notre Dame, IN. Located at : http://publicspeakingproject.org/psvirtualtext.html . Project : The Public Speaking Project. License : CC BY-NC-ND: Attribution-NonCommercial-NoDerivatives
• Martha Stewart nrkbeta. Authored by : nrkbeta. Located at : http://commons.wikimedia.org/wiki/File:Martha_Stewart_nrkbeta.jpg . License : CC BY-SA: Attribution-ShareAlike
• Seat belt BX. Authored by : M.Minderhoud. Located at : http://commons.wikimedia.org/wiki/File:Seat_belt_BX.jpg . License : CC BY-SA: Attribution-ShareAlike
• Man thinking in a bus. Authored by : IG8. Located at : https://www.flickr.com/photos/ig8/4295549232/ . License : CC BY: Attribution
• Sharia-Law-Billboard. Authored by : Matt57. Located at : http://commons.wikimedia.org/wiki/File:Sharia-law-Billboard.jpg . License : Public Domain: No Known Copyright
• Decorative toilet seat. Authored by : Bartux. Located at : http://commons.wikimedia.org/wiki/File:Decorative_toilet_seat.jpg%20 . License : Public Domain: No Known Copyright
• Image of 1993 World Trade Center bombing. Provided by : Bureau of ATF 1993 Explosives Incident Report. Located at : http://commons.wikimedia.org/wiki/File:WTC_1993_ATF_Commons.jpg . License : Public Domain: No Known Copyright

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Kinds of Arguments

Contemporary Western philosophy treats arguments as coming in two main types, deductive and inductive. The basic distinction and difference will be mentioned here.

Deductive arguments are arguments in which the premises (if true) guarantee the truth of the conclusion. The conclusion of a successful deductive argument cannot possibly be false, assuming its premises are true. This is what it means to label an argument as “valid” in logic. The form or structure of a deductive argument is the essential aspect to consider. Somewhat counter-intuitively, the premises do not need to be true for the conclusion to be true.

Arguments are a linguistic representation of an inference. So, using slightly different terminology, we can define deductive inferences . In a successful deductive inference, the premises and the denial of the conclusion constitute an inconsistent set of statements. An alternative way to describe the same relation: in a successful deductive inference, the truth of the premises makes the falsity of the conclusion logically impossible. A successful deductive inference is valid .

Deductive Example

1) All dogs are mammals.

2) All mammals breathe air.

_______________________________________________

SO: All dogs breathe air.

Inductive arguments are arguments with premises which make it likely that the conclusion is true but don’t absolutely guarantee its truth . Inductive arguments are by far the most common type of argument we see in our daily lives. We can assess inductive arguments along a spectrum of successful (stronger) to unsuccessful (weaker). The more successful (stronger) argument suggests that the premises mean the conclusion is probably true, with a high degree of likelihood. It is important to remember that inductive arguments can never fully guarantee the truth of the conclusion.

Using slightly different terminology, we can consider inductive inferences, referring to the actual thinking process in someone’s mind. In a successful inductive inference, the truth of the premises makes the falsity of the conclusion possible, but unlikely. Inductive inferences can be evaluated as “stronger” or “weaker” depending on the probability.

Inductive Example

1) The Interstate Bridge is regularly inspected by qualified engineers.

2) Vehicles have been driving over it for years.

SO: It will be safe to drive over it tomorrow.

One thing that makes applying the distinction between deductive and inductive arguments a bit tricky is this: we can’t look only at the premises OR only at the conclusion. Instead, we need to focus on the relationship between the premise(s) and the conclusion to tell what kind of argument we have.

A further contributor to trickiness: we can’t be distracted by the question of whether the statements are true or false. To classify an argument as deductive or inductive, we need to grant that the premises are true in a hypothetical way. We have to ask the question, “If those premises were true, would it be IMPOSSIBLE for the conclusion to be false?” If so, it is a deductive argument. Or “If those premises were true, would it be UNLIKELY, but still possible, that the conclusion is false? If so, it is an inductive argument.

As an example, consider this valid deductive argument:

1) All clouds are made out of spun sugar.

2) Anything made out of spun sugar is high in calories.

SO: All clouds are high in calories.

This argument is deductively successful because the truth of the premises would make the falsity of the conclusion impossible. Odd, isn’t it?

Some arguments are presented with premises missing. In those cases, the determination of deductive or inductive will depend on how that premise is filled in.

For example: I had an apple for lunch, so I had something healthy!

Exercise: Deductive or Inductive?

Determine if the following arguments are deductive or inductive. It is a good idea to put the arguments in standard form first, so you are clear about the relation between premises and conclusion.

Critical Thinking in Academic Research Copyright © 2022 by Cindy Gruwell and Robin Ewing is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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2.8: Patterns of Valid Arguments

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Obviously, valid arguments play a very important role in reasoning, because if we start with true assumptions, and use only valid arguments to establish new conclusions, then our conclusions must also be true. But how do we determine whether an argument is valid? This is where formal logic comes in. By using special symbols we can describe patterns of valid argument, and formulate rules for evaluating the validity of an argument. Below we introduce a few patterns of valid arguments. You should make sure that you can recognize these patterns and make use of them in reasoning.

Modus ponens

Consider this argument:

• If copper is a metal, then it conducts electricity.
• Copper is a metal.
• So, copper conducts electricity.

Notice that it has a similar structure compared with this one:

• If there is a storm tomorrow, the park will close.
• There will be a storm tomorrow.
• So the park will close.

Both arguments are of course valid. What is common between them is that they have the same structure or form:

• If P then Q.
• Therefore Q.

Here, the letters P and Q are sentence letters . They are used to translate or represent statements.

By replacing P and Q with appropriate sentences, we can generate the original valid arguments.

This shows that the two arguments have a common form. It is also in virtue of this form that the arguments are valid, for we can see that any argument of the same form is a valid argument.

Because this particular pattern of argument is quite common, it has been given a name. It is known as modus ponens .

However, don’t confuse modus ponens with the following form of argument, affirming the consequent, which is not valid!

• Therefore, P.

It is often a mistake to reason with an argument of this form. This is not valid:

• If Jane lives in London, then Jane lives in England.
• Jane lives in England.
• Therefore Jane lives in London.

Here are some other patterns of valid argument.

Modus tollens

• Therefore, not-P.

Here, not-Q simply means the denial of Q. So if Q means Today is hot., then not-Q can be used to translate It is not the case that today is hot, or Today is not hot.

• If there was a major earthquake, we would have felt it.
• We did not feel anything.
• So, there was no major earthquake.

But do distinguish modus tollens from the following fallacious pattern of argument, Denying the antecedent :

• Therefore, not-Q.

An example:

• If Elsie is competent, she will get a promotion.
• But Elsie is not competent.
• So she will not get a promotion.

Hypothetical syllogism

• If Q then R.
• Therefore, if P then R.

Example: If God created the universe, then the universe will be perfect. If the universe is perfect, then there will be no evil. So if God created the universe, there will be no evil.

Disjunctive syllogism

• Therefore, Q.

Example: Either the government brings about more sensible educational reforms, or the only good schools left will be private ones for rich kids. The government is not going to carry out sensible educational reforms. So the only good schools left will be private ones for rich kids.

• If P then R.
• If Q then S.
• Therefore, R or S.

When R is the same as S, we have a simpler form:

• Therefore, R.

Example: Either we increase the tax rate or we don’t. If we do, the people will be unhappy.If we don’t, the people will also be unhappy. (Because the government will not have enough money to provide for public services.) So the people are going to be unhappy anyway.

Arguing by Reductio ad Absurdum

The Latin name here simply means reduced to absurdity. It is actually an application of modus tollens . It is a method to prove that a certain statement S is false:

• First assume that S is true.
• From the assumption that it is true, prove that it would lead to a contradiction or some other claim that is false or absurd.
• Conclude that S must be false.

For example, suppose someone claims that the right to life is absolute and it is always wrong to kill a life, no matter what. Assume that this is true. We would then have to conclude that killing for self-defence is also wrong. But surely this is not acceptable. If killing an attacker is the only way to save your own life, then most people would agree that this is morally permissible. Since the original claim leads to an unacceptable consequence, we should conclude that the right to life is not absolute. This kind of reductio method is used in many famous mathematical proofs.

Other Patterns

There are of course many other patterns of deductively valid arguments. It is understandable that you might not remember the names of all these patterns. What is important is that you can distinguish the valid ones from the invalid ones, and construct examples of your own.

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To analyze an argument is to do an “active listening” step. The point is to make sure you understand what the argument actually is before turning to the evaluative question: is it a good argument?

Standard argument form is a graphical method for displaying arguments, making plain the purpose of a statement by its placement. Premises are separated, numbered, and placed above a line, and the conclusion is placed below the line. The act of inference is represented with three dots (or the word “so”) placed next to the conclusion.

_______________________________________________

Some cases are straightforward. Here is a passage, followed by the analysis into standard form.

I have a dental cleaning scheduled for June fourth. Wow, since today is the third, I guess that means the appointment is for tomorrow.

Issue: Is my dental cleaning tomorrow?

1) My dental cleaning is scheduled for the fourth.

2) Today is the third.

SO: my dental cleaning is tomorrow.

The explicit indicator word is “since.” The premise follows that indicator. The conclusion is in the clause following the comma.

If we straightened the sentence, it would read:

The appointment is for tomorrow since today is the third.

This follows a classic pattern:

(Conclusion) since (premise.)

Note: in the analysis, the words “I guess” were left out. These words signal a thinking process is happening, and can also signal how much conviction the thinker has in their own thinking. “I guess” signals a lack of confidence. If the passage had said, “that means my appointment must be tomorrow,” a higher degree of confidence would be signaled. In general, these confidence-signaling words and phrases are not themselves part of the argument.

Here is another example:

If we want to increase defense spending, we would have to either cut domestic programs or raise taxes. You know when conservatives are in control, they aren’t going to raise taxes. So, the increase in defense spending means a cut to domestic programs, for sure.

Issue: Will increased defense spending mean a cut to domestic programs?

1) To increase defense spending requires cutting domestic spending or increasing taxes.

2) Conservatives are in control.

3) Taxes won’t be increased when conservatives are in control.

SO: an increase in defense spending means a cut to domestic programs.

This analysis is more complicated, but the first step is spotting the indicator word “so.” This gives us a clue that the last sentence is the conclusion. We then articulate the issue by putting the conclusion in the form of a question. The statements preceding the conclusion indicator are premises.

We could treat this passage as listing only two premises since the premises are presented in two separate sentences. But for purposes of evaluation, it is better to list more instead of fewer premises. It allows a greater chance for finding common ground among people coming to an issue from different points of view.

Note: the phrase “for sure” in the original passage signals the thinker has a high degree of confidence in their thinking. It was left out when putting the argument into standard form.

Standard Form Examples

Most people don’t like to be lied to. So, if you lie to someone, and they find out, they are probably not going to like it.

Issue: How do people react to be being lied to?

1) Most people don’t like to be lied to

SO: if you lie to someone, they are not going to like it.

I am working full time and going to school full time, so you know I don’t get enough sleep!

Issue: Do I get enough sleep?

1) I am working full time

2) I am going to school full time

SO: I don’t get enough sleep.

Critical Thinking in Academic Research Copyright © 2022 by Cindy Gruwell and Robin Ewing is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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