According to a meta-analysis of existing studies, argument mapping classes are by far the most effective at improving critical thinking.

Claudia María Álvarez Ortiz completed an in-depth analysis regarding the most effective forms of critical thinking education in 2007. Her MA thesis was Does Philosophy Improve Critical Thinking Skills? It can be downloaded for free right here in PDF format. She wanted to know how effective philosophy classes are at teaching critical thinking compared to other classes. Her study provides evidence for the following conclusions:

1. Philosophy classes aren’t significantly more effective than many other classes at teaching critical thinking (when the classes aren’t focused on primarily teaching critical thinking) (86).
2. Critical thinking classes are effective at teaching critical thinking (ibid.).
3. Critical thinking classes taught within the analytic philosophy tradition are generally more effective than the alternatives (ibid.).
4. Critical thinking classes that teach argument mapping are by far the most effective at teaching critical thinking (87-88).

The meta-analysis suggests that the most effective class for critical thinking meets the following criteria:

1. It’s taught in the philosophy department.
2. It’s focused on critical thinking.
3. It teaches argument mapping.

It should be mentioned that the meta-analysis equates “critical thinking” with “informal logic” (11). I don’t know everything that is measured by informal logic tests, but I know that informal fallacies would be involved.

There is a “broader conception” of critical thinking that includes formal logic, creative thinking, and so on. I think formal logic (at the very least) should be included in the definition and I’m not sure why it’s usually excluded from critical thinking classes. Formal logic skills should be even easier to test than informal logic skills.

Additionally, the actual benefits various classes have on us as human beings was not mentioned in this study. At the very least, there is evidence that philosophy for children helps children in many ways (see “Philosophy for Kids”) and there’s evidence that philosophy for adults helps them do better on standardized tests (see “Philosophers Excel on Standardized Tests”).

Finally, I am confident that there are benefits for attaining informal logic skills as well, but I do not know of any studies that tell us exactly what those benefits are. Even so, I would expect the following benefits to be included:

1. Better ability to persuade others.
2. Better ability to correct one’s beliefs that rely on poor reasoning.
3. Identifying deception, such as the manipulation commonly used by politicians, quacks, and cults.

Related:

• Introduction to Critical Thinking & Argument Mapping
• A Study Finds That Formal Logic Can Help High School Students

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Filed under: philosophy Tagged: argument mapping, argumentation, critical thinking, education, justification, logic, rationality, reasoning

I have discussed ten concepts that are related to argumentation, but there are many other concepts that are related to critical thinking that we should know about. Many of these concepts might sound like ordinary words, but the meaning of the words within the context of critical thinking is often quite different than what we might expect. That’s all the more reason why a clarification of these concepts within a critical thinking context can be very helpful.

I will now discuss the following eight concepts:

1. Explanation
2. Disagreement
3. Debate
4. Criticism
5. Rational
6. Logic
7. Valid
8. Philosophy

Explanation

Explanations are the reasons things are the way they are. Hypotheses and scientific theories are examples of explanations. The explanation for why things fall is the “law of gravity.” The explanation for why people can see is because they have eyes. Scientific explanations tell us why things are the way they are, and they can help us make predictions.

Philosophers develop many explanatory theories involving logic, morality, and metaphysics. For example, utilitarianism is a moral theory that—roughly speaking—states that we should try to make people happier and reduce their pain. We can use that theory to know why and when actions are morally right or wrong. If we consider all the actions we can do and one action makes people happiest (and/or less miserable) compared to all our other options, then that action would be morally right.

People often confuse explanations and arguments. Explanations don’t tell us why we should believe something. Consider the explanation that states “we have day and night because the Earth is spinning.” We know we have day and night from our observations of the world, not because the Earth is spinning.

Disagreement

A disagreement is what happens when two people have incompatible beliefs. For example, one person might think intelligent life probably exists on another planet, and another person might think intelligent life probably doesn’t exist on another planet.

Disagreements are often a reason people have a conversation and it can often motivate people to argue. If someone disagrees with you, then you might want to educate the other person as to why you think your belief is justified (or why you think the other person’s belief is unjustified).

Even so, not all arguments are meant to settle disagreement. Arguments can be made merely to state how we know what we know, why our beliefs are justified, or to consider the evidence for our beliefs.

Debate

A debate is a discussion where two people who disagree present arguments in favor of a certain belief and against the belief held by the “other side.” Debates also generally involve arguments against arguments.

Debates generally involve a lot of back and forth where one person tries to refute the arguments of another and the other person tries to refute the refutations. Consider the following debate:

Tabitha: We should abolish the death penalty because human life has value.

Dawn: The death penalty might save lives, so the value of human life is irrelevant.

Tabitha: There is no evidence that the death penalty saves human lives.

Dawn: I find it likely that the death penalty can save lives because it can deter criminals who decide not to murder others out of fear of punishment.

Tabitha: There is little to no evidence that the death penalty deters murders in that way, and the death penalty might give the impression to people that human life is worth sacrificing for various goals.

Many people have the impression that debates are hostile disagreements, shouting matches, or a manipulative and disrespectful exchange of ideas. That is not what debate refers to within the context of critical thinking.

Some debates are “public debates” with a moderator, and a limited time given to each side. That is not what debates refer to in a critical thinking context. What matters in critical thinking is how well you can argue and how justified your beliefs are. How well you can persuade an audience in a given amount of time is not relevant and could even be an indication of emotional manipulation.

Some debates in philosophy have lasted thousands of years with several authors participating and writing their arguments down in various books. Almost every philosophy essay written by philosophy professors is part of a debate.

Criticism

We often think of criticism as insults or disparaging remarks, and many people say we shouldn’t criticize others. However, that is not what criticisms are in a critical thinking context. Instead, it refers to an argument that attempts to oppose another argument or belief. Criticisms are also known as “objections, refutations, counter-arguments, or negative arguments.”

An example of a criticism is the following:

1. Hanna believes that platypuses are birds because they have bills and lay eggs, like ducks.
2. However, Hanna didn’t mention that platypuses have fur and produce milk for their young, like mammals.
3. Therefore, Hanna’s argument left out important information.

Rational

The words “rational” and “reasonable” are generally considered to be synonyms. People are said to have the power of “reason” and are “rational animals.” In the context of critical thinking, these words are generally attached to beliefs. A belief is “sufficiently justified” if it’s rational to hold the belief. Rational beliefs are “good enough” because the person either has a good reason to have the beliefs or don”t have a good reason to reject the beliefs.

How do we know when a belief is “rational?” How do we know what criteria determines when beliefs are “rational?” Part of the answer to these questions has been answered by logicians. For example, we know it is irrational to hold beliefs because of fallacious arguments (bad kinds of arguments). Even so, there is a lot we are still learning about rationality and it falls within the philosophical domain called “epistemology” or “the study of knowledge.”

Logic

There are two main domains of logic within the philosophical domain—informal logic and formal logic. Informal logic concerns an understanding of argumentation and informal fallacies. Formal logic concerns argument form (also known as “argument structure”).

There are objective criteria that determines when an argument is “logical” within the critical thinking context. Logic involves rigor and precision far beyond what you should ever expect in a casual conversation.

Outside of the critical thinking context people use the word “logic” very loosely and often seem to think that “logical arguments” are “whatever arguments sound good.” That is not the case in the critical thinking context. What sounds good can be manipulative and unreasonable.

The fact that people define the word “logic” in such imprecise, unclear, and loose ways outside of the critical thinking context could be an indication for why so few people think they should learn logic. They already know what arguments “sound good,” so what’s the point? The point is that there’s a great deal of clarity, rigor, and precision that logic classes can offer us. People are generally good at knowing when arguments are good, but they make mistakes. Understanding logic of the critical thinking variety can help us makes less mistakes and put our minds to better use.

Valid

In the critical thinking context, an argument is valid if it’s impossible for its premises to be true and conclusion to be false at the same time; and invalid arguments could have true premises and a false conclusion at the same time. It’s generally important to have valid arguments because it helps assure us that our arguments prove conclusions to be true.

An example of a valid argument is the following:

1. If lizards are mammals, then lizards are animals.
2. Lizards are mammals.
3. Therefore, lizards are mammals.

The second premise is false—lizards are not actually mammals. Even so, this argument is logically valid because it would be impossible for the conclusion to be false assuming the premises are true. Valid arguments are not necessarily “good arguments.” Valid arguments have something good going for them, but might not have everything good going for them.

An example of an invalid argument is the following:

1. If lizards are reptiles, then lizards are animals.
2. Lizards are animals.
3. Therefore, lizards are reptiles.

The premises and conclusion are all true, but the argument is invalid because the premises could be true and the conclusion could be false. In other words, the premises are insufficient to prove the conclusion to be true. Lizards would be animals, even if they are mammals. If we assume that lizards are mammals, then the conclusion would be false, even though the premises could both be true.

Like the word “logical,” people use the word “valid” very loosely outside of the critical thinking context. A “valid point” or “valid argument” in a casual context seems to mean something like “it sounds good to me.” Again, this is much less technical, rigorous, and clear than what the word means within the critical thinking context. “Logicians” are not just saying what sounds good to them. They’re using high standards of rationality to make various discoveries.

Philosophy

Philosophy, broadly speaking, is a rigorous attempt to debate and make good arguments. While engaging in philosophy, we can consider various viewpoints against our beliefs, try to make sure our beliefs are all consistent, try to make sure our beliefs are justified, and so on.

The word “philosophy” within everyday life often refers to personal beliefs or personal policies. For example, a person might say, “A penny saved is a penny earned—That’s my philosophy!” That’s not what philosophy refers to within the critical thinking context. It has nothing to do with what “philosophy professors” study.

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Filed under: philosophy Tagged: argumentation, critical thinking, education, justification, logic, rationality, reasoning

The most important concept related to critical thinking is that of argumentation. An argument is a group of two or more statements when one statement (the conclusion) is supposed to be justified because the other statement(s) (the premises) are true. An example of a good argument is the following:

1. All men are mortal.
2. Socrates is a man.
3. Therefore, Socrates is mortal.

In this case the first two statements are premises and the last statement is a conclusion. The conclusion is justified because we know the first two statements are true. It would be impossible for the conclusion to be false precisely because we know the premises are true.

Not all arguments are good. For example, the following is an unreasonable argument:

1. All men are mortal.
2. Socrates is mortal.
3. Therefore, Socrates is a dog.

In this case the the premises do not justify the conclusion. Based on the premises, Socrates could be a cat, a man, or any number of other creatures that are mortal.

I will (1) discuss why arguments exist, (2) give more examples of good arguments, (3) give more examples of bad arguments, and (4) discuss why arguments make people angry.

(1) Why do arguments exist?

An important consideration when thinking about arguments is the purpose of them. The most common reason to present an argument is for rational persuasion—to convince someone that something is true because the belief is more justified than the alternatives.

Arguments can be meant to answer various questions, such as the following:

1. How do you know?
2. Why should I agree?
3. Why is that belief justified?
4. What’s the evidence in support of that belief?

(2) Three more examples of good arguments

Example 1

1. No fish are warm-blooded.
2. Whales are warm-blooded.
3. Therefore, wales are not fish.

Example 2

1. If the using atomic bombs on human beings kills them, then (at minimum) we generally shouldn’t use atomic bombs on human beings.
2. Using atomic bombs on human beings kills them.
3. Therefore, (at minimum) we generally shouldn’t use atomic bombs on human beings.

Example 3

1. People who make mistakes without realizing they are making mistakes are more likely to continue to make mistakes.
2. People who are close-minded are less likely to realize they are making mistakes.
3. We should generally want to stop making mistakes.
4. Therefore, we should try not to be close-minded.

(3) Three examples of bad arguments.

Example 1

1. All reptiles are animals.
2. All lizards are reptiles.
3. Therefore, no lizards are animals.

In this case we know all lizards are animals, so the conclusion is false. The premises do not give us a reason to think the conclusion is true.

Example 2

1. People who are gullible are more likely to believe lies.
2. We should want to believe lies.
3. Therefore we should want to be gullible.

In this case if the premises are true, then the conclusion is true. However, a premise is blatantly false because it’s false that we should want to believe lies. Only bad arguments contain blatantly false premises.

Example 3

1. If shooting people with machine guns often causes them to die, then we have a reason to think that shooting people with machine guns is generally morally wrong.
2. Shooting people with machine guns often causes them to die.
3. Therefore, it’s always morally wrong to use marijuana.

In this case the conclusion is totally unrelated to the premises. A much more reasonable conclusion would be, “Therefore, we have a reason to think that shooting people with machine guns is generally morally wrong.”

(4) Don’t arguments make people angry?

Good arguments are a respectful form of persuasion that appeals to a person’s capacity to reason and interest in knowing the truth. However, many people think the word “argument” refers to a shouting match or unpleasant disagreement. Perhaps that is one meaning of the word, but it is not the meaning we are interested in within the critical thinking context. Even so, it is quite possible for people to give genuine arguments during a shouting match or unpleasant disagreement, and giving “good arguments” can make people very angry. They might think you are being pushy or are being unpleasantly disagreeable. Some people think all debate and arguments are disrespectful and disagreeable because they equate some horrible sort of argumentation with all rational forms of argumentation. However, they should not equate the two. They are different things.

It is much more disrespectful to never use arguments of the critical thinking variety. To never tell people they are wrong (and why) is to treat them as irrational beings who can’t handle the truth.

Imagine if biology teachers refused to tell students that whales aren’t fish because whales are warm-blooded and fish are cold-blooded. There’s no reason to keep kids in the dark just because it might shatter their unjustified sense of confidence.

It is true that finding out our beliefs are false can shatter our sense of confidence and sometimes we might feel bad if we were particularly attached to our belief for some reason. Consider how heart-breaking it can be to find out there is no Santa Claus. At the same time the risks of finding out the truth are generally (or always) worth taking. The benefits almost always outweigh the harm.

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Filed under: philosophy Tagged: argumentation, critical thinking, education, fallacies, justification, logic, rationality, reasoning

You might want to read Informal Fallacies part 1, part 2, part 3 , and part 4 before reading this.

I will present 20 arguments. I will discuss whether or not the argument contains an informal fallacy and, if so, how we can object to it (and create an argument map for the objection). Keep in mind that my answers can legitimately differ from yours and many of the fallacies overlap. Keep an eye out for the following 12 fallacies:

1. Red herring
2. Straw man
3. Appeal to authority
4. Hasty generalization
5. Appeal to ignorance
6. Slippery slope
7. Begging the question
8. False dilemma
9. Accident
10. One-sidedness
11. Equivocation
12. Continuum

The arguments

Argument 1

1. People who argue get angry at each other.
2. If people who argue get angry at each other, then we shouldn’t argue.
3. Telling children they generally shouldn’t hurt each other “because other people matter too” is an argument.
4. Therefore, we should not tell children they generally shouldn’t hurt each other “because other people matter too.”

This argument contains an equivocation fallacy.

This argument first talks about how arguments are “hostile disagreements” involving anger and later talks about how arguments are used for rational persuasion. The argument rejects using rational persuasion with children because it also rejects arguments as hostile interactions. However, we are dealing with two different definitions of “argument” here and they should not be confused. The argument requires this confusion, so the equivocation fallacy is committed.

Keep in mind that if the argument uses two definitions for the word “argument,” then we can rephrase the argument as, “People who have hostile disagreements get angry at each other; if people who have hostile disagreements get angry at each other, then we shouldn’t have hostile disagreements; telling children they generally shouldn’t hurt each other ‘because other people matter too’ is rational persuasion; therefore, we should not tell children not to hurt each other ‘because other people matter too.’”

My objection to the fallacious argument can be stated as follows:

1. The above argument requires that we use two different definitions for the word “argument.”
2. If the above argument uses two different definitions for “argument,” then it’s logically invalid.
3. Therefore, the above argument is logically invalid.

We can justify the second premise with the following argument:

1. If the argument uses two definitions for the word “argument,” then the argument form is “A; if A, then we shouldn’t B; C is a D; therefore, we shouldn’t C.”
2. The argument is logically invalid if another argument can have the same form, true premises, and a false conclusion.
3. “People who attack innocent people often hurt innocent people; if people who attack innocent people often hurt innocent people, then we generally shouldn’t innocent people; criticizing good-intentioned politicians for having bad policies makes politicians look bad; therefore, we shouldn’t criticize good-intentioned politicians for having bad policies” has the same form, true premises, and a false conclusion.

Click here to see the argument map of this objection.

Argument 2

1. Linda argued that we know it’s morally right to hurt people who have red hair (just because they have red hair) because people with red hair are inferiors.
2. Linda clearly does not think people with red hair deserve the same respect as all other people.
3. People who have red hair are not inferiors.
4. If Linda’s premise is false, then her argument gives us no reason to agree with her conclusion.
5. Therefore, Linda’s argument does not give us reason to agree with her conclusion.

There are no informal fallacies in this argument. We might suspect that a straw man argument is involved because someone else’s argument is mentioned, but nothing uncharitable is said about the argument. The objection given against Linda’s argument contains no major errors.

Argument 3

1. Sally argued that it’s usually wrong to hurt people because we should care about other people.
2. Sally clearly thinks it’s always wrong to hurt people, even when it is necessary to hurt others to protect ourselves in self-defense.
3. We know that its not wrong to hurt people when necessary for self-defense.
4. Therefore, Sally’s conclusion is false.

This argument contains a straw man fallacy.

We should look out for a straw man argument because someone else’s argument is mentioned and objected to. Additionally, Sally’s argument is uncharitably described. Sally did not say she thinks it’s always wrong to hurt people; she merely said it’s usually wrong. It’s uncharitable to Sally’s argument to distort it in this way. The objection is irrelevant because the objection is against a conclusion that Sally didn’t even argue for.

My objection to the above fallacious argument can be stated as follows:

1. Sally states that it’s usually wrong to hurt people.
2. A premise states that Sally thinks it’s always wrong to hurt people.
3. We are not given any reason to think the premise is true.
4. If we are not given any reason to think the premise is true, then it’s unjustified (because it contradicts what Sally said).
5. Therefore, the premise is unjustified.

Click here to see the argument map of this objection.

Argument 4

1. Kara says it’s never wrong to hurt people.
2. If it’s never wrong to hurt people, then it’s never wrong to stab people with knives.
3. If it’s never wrong to stab people with knives, then it’s never wrong to kill people with knives.
4. Therefore, Kara’s statement implies that it’s never wrong to kill people with knives.

This argument contains no informal fallacies. We could look for a slippery slope fallacy because many implications of a position are discussed, but all the implications are justified. Stabbing people with knives is one way we can hurt them, and killing people with knives could happen when we stab people with them.

Argument 5

1. If we have gun registration, then we will eventually ban automatic weapons.
2. If we ban automatic weapons, then we will eventually ban all guns.
3. We shouldn’t ban all guns.
4. Therefore, we shouldn’t have gun registration.

This argument contains a slippery slope fallacy.

There are many causal steps listed, and each of them are part of a longer causal chain that leads to something bad. That’s enough to know that a slippery slope is involved, but it is possible to have a non-fallacious slippery slope. Nonetheless, the slippery slope is fallacious because we don’t know that these acts will have the causal impacts that are mentioned.

An objection to the above fallacious argument is the following:

1. No evidence is mentioned supporting the first two premises.
2. If no evidence is mentioned supporting the first two premises, then they are unjustified (because causal claims are unjustified unless we can prove they are true).
3. Therefore, the first two premises are unjustified.

Click here to see the argument map of this objection.

Argument 6

1. Jack is running for sheriff and says he should get the job because he’s a war hero.
2. However, Jack was found guilty of many corruption charges while he was a Mayor.
3. We shouldn’t trust war heroes to be a sheriff who have been found guilty of corruption charges.
4. Therefore, Jack shouldn’t get the sheriff job.

No informal fallacies are committed here. We might suspect that a straw man argument is committed because it mentions the argument of someone else, but nothing uncharitable is said concerning Jack’s argument. The argument given against Jack is not a fallacious one because the flaws discussed are perfectly relevant to whether or not Jack should get the job.

Argument 7

1. Adam argues that racism is wrong because all racial groups are equal.
2. However, Adam murdered ten people.
3. We shouldn’t trust murderers.
4. Therefore, we should reject Adam’s argument.

This argument contains a red herring fallacy.

We might suspect that a straw man argument is committed because someone else’s argument is mentioned. However, nothing uncharitable is said concerning Adam’s argument. We can realize a red herring fallacy is committed because nothing relevant is said concerning Adam’s argument—and yet it says we should reject Adam’s argument. The argument claims that we should reject Adam’s argument because he’s a murderer, but even murderers can give good arguments. Therefore, this argument could be taken to be a distraction rather than as engaging in a genuine debate.

An objection to the above fallacious argument can be stated in the following way:

1. It is possible for murderers to give us good arguments.
2. If it is possible for murderers to give us good arguments, then the premises are irrelevant.
3. Therefore, the premises are irrelevant.

Click here to see the argument map of this objection.

Argument 8

1. Whales live in the ocean and have fins.
2. Fish live in the ocean and have fins.
3. If whales have characteristics of fish rather than mammals, then it’s likely that whales are fish.
4. Therefore, it’s likely that whales are fish.

This argument engages in one-sidedness.

It is true that whales have characteristics of fish, but whales have even more characteristics of mammals. If this argument is two-sided and gives us all the relevant information for both sides, then no fallacy is committed. The problem with the argument is what is left out—the evidence that whales have characteristics of mammals is ignored. That means the argument commits the one-sidedness fallacy.

An objection to the above fallacious argument can be stated in the following way:

1. The above argument requires the assumption that whales have characteristics of fish rather than mammals.
2. However, this assumption is false.
3. If this assumption is false, then the above argument fails to prove that the conclusion is true.
4. Therefore, the above argument fails to prove that the conclusion is true.

Click here to see the argument map of this objection.

Argument 9

1. If all animals with bills are birds, then platypuses are birds.
2. We should assume all animals with bills are birds.
3. Therefore, we should assume that platypuses are birds.

This argument commits the begging the question fallacy.

The problem with this argument is that the most controversial premise is assumed—that we should assume that all animals with bills are birds. If that’s true, then it’s trivial that platypuses are birds. However, we can’t just assume that controversial premises are true that would trivially lead to the conclusion we want. When we do that, we beg the question. Therefore, this argument begs the question.

An objection to the above fallacious argument can be stated in the following way:

1. If the second premise is a scientific hypothesis and no evidence supports it being true, then the premise is unjustified.
2. The second premise is a scientific hypothesis and no evidence supports it being true.
3. Therefore, the second premise is unjustified.

Click here to see the argument map of this objection.

Argument 10

1. Physicists agree that Einstein’s theory of physics is more complete than Newtan’s theory of physics.
2. If physicists agree about something within their field of expertise, then we should agree with them.
3. Therefore, we should agree that Einstein’s theory of physics is more complete than Newtan’s theory of physics.

This argument contains no informal fallacies. It is an appeal to authority because it relies on the expert opinions of physicists to justify what beliefs we should have. However, it is a non-fallacious appeal to authority because the experts agree and have the relevant expertise. (Medical doctors are not the appropriate sort of expert concerning physics, but physicists are.)

Argument 11

1. Many war heroes agree that we shouldn’t legalize same-sex marriage.
2. If war heroes believe something, then we should agree with them.
3. Therefore, we should agree that we shouldn’t legalize same-sex marriage.

This argument commits the appeal to authority fallacy.

The “expert opinion” of war heroes is not relevant to political, legal, or ethical knowledge; and not all war heroes agree about what laws we should have anyway.

This could also be considered to be a red herring fallacy because the opinions of war heroes is irrelevant to the conclusion and could used as a distraction from genuine debate.

An objection to the above fallacious argument can be stated in the following way:

1. War heroes are not experts about whether we should legalize same-sex marriage.
2. If war heroes are not experts about whether we should legalize same-sex marriage, then it’s false that “if war heroes believe something, then we should agree with them.”
3. Therefore, the second premise is false.

Click here to see the argument map of this objection.

Argument 12

1. There is no good evidence that unicorns exist.
2. If unicorns exist, then we would have probably found good evidence of them by now.
3. Therefore, unicorns probably don’t exist.

This argument contains no informal fallacies. We might suspect that this is an appeal to ignorance fallacy because a lack of evidence doesn’t prove that unicorns don’t exist. However, it is also true that we would expect to find evidence of unicorns if they exist. Many people have spent a lot of time looking around for new species and would love to prove unicorns exist.

Argument 13

1. There is no proof that bigfoot doesn’t exist.
2. If there is no proof that bigfoot doesn’t exist, then we should assume that bigfoot exists.
3. Therefore, we should assume that bigfoot exists.

This argument commits the appeal to ignorance fallacy because it uses a lack of proof as evidence that we should believe something. If bigfoot doesn’t exist, then there’s even a higher chance that we wouldn’t have any proof that it exists.

An objection to the above fallacious argument can be stated in the following way:

1. If there is no proof that unicorns exist, then we should not assume that unicorns exist.
2. If we should not assume unicorns exist due to a lack of evidence, then we should not assume bigfoot exists due to a lack of evidence.
3. The second premise is false.

Click here to see the argument map of this objection.

Argument 14

1. Every human in recorded history was mortal.
2. If every human in recorded history was mortal, then every human is probably mortal.
3. Therefore, every human is probably mortal.

This argument contains no informal fallacies. We might suspect that this is a hasty generalization because the argument requires us to generalize. However, this is a perfectly reasonable sort of generalization.

Argument 15

1. There are testimonials of people who use homeopathic remedies who got healthier after using them.
2. If there are testimonials of people who use homeopathic remedies who got healthier after using them, then the homeopathic remedies probably make people healthier.
3. Therefore, the homeopathic remedies probably make people healthier.

This argument commits the hasty generalization fallacy.

Testimonials are infamously used as “anecdotal evidence” and people often fallaciously generalize from a few cases to everyone (or themselves). If you get healthier after taking a remedy, it is quite possible that you would have got better anyway.

An objection to the above fallacious argument can be stated in the following way:

1. It is possible to get healthier after using so-called remedies that don’t actually help us.
2. If it is possible to get healthier after using so-called remedies that don’t actually help us, then testimonials are not evidence that homeopathic remedies probably make us healthier.
3. If testimonials are not evidence that homeopathic remedies probably make people healthier, then the second premise is false.
4. Therefore, the second premise is false.

Click here to see the argument map of this objection.

Argument 16

1. We generally shouldn’t attack people.
2. If we generally shouldn’t attack people, then there are many situations in which we should not attack other people.
3. Therefore, there are many situations in which we should not attack other people.

This argument contains no informal fallacies. We might suspect that the “accident” fallacy is committed because a general rule is involved, but the general rule is used appropriately.

Argument 17

1. Around 50% of the population gets married at least once.
2. Therefore, Oprah Winfrey has around a 50% chance of getting married at least once.

This argument contains the accident fallacy.

We know this argument is fallacious because we can’t apply general rules to specific situations or people without additional information. We could only do that if general rules apply to all situations, but they don’t. That’s why we say there are “exceptions to the rule.”

An objection to the above fallacious argument can be stated in the following way:

1. The above argument requires the assumption that Oprah Winfrey has the same odds of getting a diverse as everyone else.
2. We can’t apply general rules to all cases.
3. If we can’t apply general rules to all cases, then the assumption that Oprah Winfrey has the same odds of getting a diverse as everyone else is unjustified.
4. Therefore, the above argument requires an unjustified assumption.

Click here to see the argument map of this objection.

Argument 18

1. Either people learn logic or they generally have a higher chance of making logical mistakes.
2. Many people do not learn logic.
3. Therefore, many people generally have a higher chance of making logical mistakes.

This argument contains no informal fallacies. We might suspect that this argument is a false dilemma because there might be more options than are listed here, but that is probably not the case for this argument. There might be some people who would make less logical mistakes without learning anything about logic, but that is not usually the case. Learning logic tends to help people make less logical mistakes.

Argument 19

1. Either Newton’s theory of physics is perfect or Einstein’s theory of physics is perfect.
2. Newton’s theory of physics is not perfect.
3. Therefore, Einstein’s theory of physics is perfect.

This argument commits the false dilemma fallacy.

Although Eisntein’s theory of physics is superior to Newton’s theory of physics, we don’t know that Einstein’s theory is “perfect.” There might still be corrections to be made, or it might be incomplete, or a superior theory of physics might be developed in the future. There are more options than are listed here and yet the argument depends on there only being two possibilities. Therefore, the argument commits a false dilemma fallacy.

An objection to the above fallacious argument can be stated in the following way:

1. We might not know the perfect theory of physics.
2. If we might not know the perfect theory of physics, then the first premise is unjustified.
3. Therefore, the first premise is unjustified.

Click here to see the argument map of this objection.

Argument 20

1. If I drink one molecule of water, it will have no benefit for me.
2. If I drink two or three molecules of water, it will have no benefit for me.
3. We don’t know how to draw the line about how many molecules of water I’d have to drink for it to benefit me.
4. Therefore, drinking water will have no benefit for me.

This argument commits the continuum fallacy.

Something vague is discussed—how much water I have to drink to have a benefit, and conclusions are drawn based on the fact that we don’t know where to “draw the line.” However, we know that drinking water does benefit us, even though we don’t know where we should “draw the line.” We simply don’t need to know where to draw the line for water to benefit us.

An objection to the above fallacious argument can be stated in the following way:

1. The above argument requires the assumption that we can’t be benefited by something unless we know where to draw the line concerning when we have enough of it to benefit us.
2. We don’t know exactly how much vegetables we have to eat to benefit us.
3. If we don’t know exactly how much vegetables we have to eat to benefit us, then it’s false that we can’t be benefited by something unless we know where to draw the line concerning when we have enough of it to benefit us.
4. Therefore, the above argument requires a false assumption.

Click here to see the argument map of this objection.

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You might want to read Informal Fallacies part 1 and part 2 before reading this.

Fallacies of presumption involve unreasonable and unwarranted assumptions. I will discuss the following three fallacies of presumption: (1) begging the question, (2) false dilemma, (3) accident, and (4) one-sidedness.

(1) Begging the question

The begging the question fallacy is committed when the argument offered requires us to either assume that the conclusion is true or that a controversial premise is true that would make the conclusion a trivial consequence. These arguments provide none of the evidence that would be required to prove the conclusion is true.

An extreme form of begging the question is the “circular argument,” which has a premise that contains the conclusion. “All dogs are mammals because all dogs are mammals” is a circular argument. No evidence is given by this argument to accept the conclusion despite the fact that it’s logically valid.

Another example of begging the question is the following argument:

1. It’s always wrong to kill people.
2. If it’s always wrong to kill people, then it’s always wrong to kill murderers.
3. Therefore, it’s always wrong to kill murderers.

The argument map for this is the following:

The problem with this argument is that the conclusion is a trivial consequence of assuming that it’s always wrong to kill people. The second premise is uncontroversial, but the first premise—that it’s always wrong to kill people—is not obvious.

To explicitly object to arguments that beg the question, we should make it clear that the argument is circular or fails to provide evidence for a controversial premise.

An explicit objection to the above fallacious argument is the following:

1. The above argument requires us to agree that “it’s always wrong to kill people,” but it gives us no reason to agree with this controversial premise.
2. If an argument requires us to agree with a controversial premise and it doesn’t give us any reason to agree with it, then the argument begs the question.
3. Therefore, the above argument begs the question.

The argument map for this objection is the following:

(2) False Dilemma

An argument is a false dilemma when it requires us to assume there are only so many possibilities when even more possibilities are plausibly available. A false dilemma can be logically valid, but the argument fails to give us a reason to agree with the conclusion because it’s unreasonably demanding us to dismiss or ignore certain relevant options.

An example of a false dilemma is the following:

1. Either matter can be created without cause or God created the universe.
2. It is false that matter can be created without cause.
3. Therefore, God created the universe.

The argument map for this false dilemma is the following:

This argument is a false dilemma because there are plausible alternatives that are left out. Perhaps the universe always existed. If so, we can’t conclude that God created the universe even if we agree that matter can be created without cause. First we would have to prove that the universe didn’t always exist.

When we object to false dilemmas, we can make it clear that we are required to unreasonably restrict our options when more options should be considered.

An example of an objection to the above false dilemma is the following:

1. The above argument requires that there are only two reasonable possibilities—either (1) matter can be created without cause or (2) God created the universe.
2. However, there is at least one other reasonable possibility—perhaps the universe was not created after all.
3. If the argument requires only two reasonable possibilities, but more than two reasonable possibilities exist, then the argument will fail to give us a reason to agree with the conclusion.
4. Therefore, the above argument fails to give us a reason to agree with the conclusion.

The argument map for this objection is the following:

(3) Accident

The “accident” fallacy takes a general rule and applies it in an inappropriate way. General rules tell us what is usually the case rather than always the case. For example, it’s a general rule that birds can fly, but not all birds can fly. For example, ostriches.

An example of an argument that uses the accident fallacy is the following:

1. 50% of marriages end in divorce.
2. Therefore, President Obama has a 50% chance of getting a divorce.

The argument map for this argument is the following:

This is an accident fallacy because this statistic can’t be used to make predictions about specific people. There are many factors that determine the likelihood of getting a divorce. (We could conclude that a random person that we know nothing about has a 50% of getting a divorce only because we wouldn’t have enough information to make a better estimation.)

In order to object to an accident fallacy, you can make it clear that a general rule is being considered that does not apply in every case.

We can explicitly state an objection to the above fallacious argument as the following:

1. The argument requires the assumption that “if 50% of marriages end in divorce, then President Obama has a 50% chance of ending in divorce.”
2. However, there are many factors that we should use when determining the probability of divorce rather than just use the average for all people.
3. If there are many factors that we should use when determining the probability of divorce rather than just use the average for all people, then the assumption that “if 50% of marriages end in divorce, then President Obama has a 50% chance of ending in divorce” is unjustified.
4. Therefore, the assumption that “if 50% of marriages end in divorce, then President Obama has a 50% chance of ending in divorce” is unjustified.

The argument map for this objection is the following:

(4) One-sidedness

It is often important for arguments to account for the reasons for and against various beliefs. Debates are very educational because they present two sides and it’s important for debaters to respond to the objections given by others. It’s often a good idea to seek out and consider the arguments of those who disagree with us precisely so (a) we don’t unreasonably dismiss the evidence against our beliefs, and (b) we can correct our beliefs whenever we find out they’re unjustified. One-sidedness is what often happens when we fail to take account of “both sides” of an issue.

One-sidedness is one of the most popular fallacies, which is also known as “cherry picking” or “suppressed evidence.” When we make certain strong claims, we need strong evidence to prove our claim to be justified. Strong evidence must include all the most relevant pros and cons for believing the claim being made. To neglect to mention various objections to a claim can make a claim seem more reasonable than it really is. We therefore need to make sure that our arguments and discussions are two-sided whenever necessary. For example, we can’t think that free speech justifies making promises of reward for an assassination because it violates someone else’s right to life. Both rights should be considered. To ignore the rights to life would require us to have a one-sided argument.

An example of a one-sided argument is the following:

1. Susan argues that a war with another country would cost a lot of money and lead to the death of many people.
2. However, the USA can attack other countries to take their oil.
3. If the USA can attack other countries to take their oil, then it should do so.
4. Therefore, the USA should attack other countries to take their oil.

An argument map for this argument is the following:

This argument is one-sided because it ignores the reasons why going to war could be a bad idea (it costs money and many people will die). One possible positive benefit (getting oil) is merely one consideration in favor of going to war. We should consider all the reasons for and against going to war before we conclude whether it should happen.

When explicitly objecting to a one-sided argument, we should make it clear that there is important evidence against the conclusion that has been left out.

We can explicitly object to the above one-sided argument in the following way:

1. The above premise is only true if attaining oil is a sufficiently good reason to go to war.
2. If there are other considerations that might be of greater important than attaining oil, then the premise is false.
3. The financial cost and lost lives can both be more important than attaining oil.
4. Therefore, the above premise is false.

The argument map for this objection is the following:

Updated (3/20/2011): I added the one-sidedness fallacy to the list.

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(You might want to review my “Introduction to Argument Mapping” before reading this.)

Fallacies are errors in reasoning. We often find fallacious arguments to be persuasive—at least until we know what’s wrong with them. Even so, fallacious arguments are generally only given when we are thinking poorly or trying to manipulate the minds of others. There is much to be said about what is required of good arguments, and the least controversial requirement is that no fallacies are committed.

I have already discussed formal fallacies—logically invalid argument forms. Informal fallacies are errors of reasoning that don’t merely involve the argument form.

I have already discussed how we can give objections to logically invalid arguments. However, it is much more common to object to arguments that commit informal fallacies. I will focus on how we can object to informally fallacious arguments.

Fallacies of relevance

I will discuss three fallacies of relevance—red herring, straw man, and appeal to authority. Good arguments need relevant supporting evidence and good arguments within a debate must be relevant to the other arguments within the debate. Fallacies of relevance fail to live up to these principles.

(1) Red herring

The red herring fallacy is committed during a debate by saying something mostly irrelevant to distract people or change the subject. Generally what is said focuses the attention on the opponent or the opponent’s argument in order to avoid one’s own failings (or the failings of one’s own argument). The most common form of red herring is meant to discredit the opponent by discussing the failings of the opponent (or those who associate with the opponent), but a red herring can also be used to discuss the moral superiority of yourself or those you associate with.

Red herrings do not necessarily lead to an illegitimate conclusion. Instead, we tend to want to avoid them for being unproductive within a debate.

An example of a red herring fallacy is the following:

1. The President wants to have social programs to help the poor.
2. However, totalitarian communists wanted to have social programs to help the poor.
3. Totalitarian communists, like Stalin, killed millions of innocent people.
4. Therefore, we shouldn’t have social programs for the poor.

The map for this argument is the following:

In the above argument the mere association of totalitarian communists and social programs for the poor is meant to discredit them. However, it is quite possible that evil totalitarian communists did some things right. Consider the view that everything totalitarian communists do is wrong. In that case, we shouldn’t eat or drink because so did Stalin.

In order to give an objection to a red herring, you can make sure to point out that the argument is irrelevant to the debate and explain why you think the argument is irrelevant. For example, we can explicitly object to the above fallacious argument in the following way:

1. The premises are irrelevant to the conclusion unless everything totalitarian communists do is wrong.
2. Not everything totalitarian communists do is wrong.
3. Therefore, the above premises are irrelevant to the conclusion.

The map for this objection is the following:

(2) Straw man

We should be charitable to those we disagree with and try to understand why intelligent people disagree with us. The straw man fallacy is what can happen when we are uncharitable to others. The straw man fallacy is committed by mischaracterizing the arguments of others in a way that makes the arguments of others seem less reasonable. We can create straw man arguments by changing the arguments given by our opponents slightly or by ignoring the actual arguments given them entirely and making up some totally different argument. This is generally done in order to easily discredit arguments we disagree with. However, the actual argument given by an opponent was never actually discredited. We can’t discredit the actual arguments given by others if we make the argument less reasonable than they really are.

An example of a straw man fallacy is the following:

1. Scientists believe in evolution because they reject God and need an atheistic explanation for where complex organisms came from.
2. Once we realize God exists, we don’t need an atheist explanation for where complex organisms came from.
3. Therefore, theists should reject evolution.

The map for this argument is the following:

This argument is an extreme sort of straw man argument because it ignores all the evidence for evolution actually given by biologists and merely gives a psychological motivation behind why scientists might want to justify the theory of evolution. The reason to believe in evolution given above certainly is not the strongest argument for evolution.

In order to give an explicit objection to a straw man fallacy, we should point out that the best argument for a position is being ignored or distorted, and the opponent has replaced the best argument with something less reasonable. For example, we can explicitly object to the above fallacious argument in the following way:

1. The above argument describes a reason to believe in evolution as, “Scientists reject God and need an atheistic explanation for where complex organisms came from.”
2. However, the above argument states a significantly worse argument for evolution than are available. (Rejecting God is not evidence for evolution and there is physical evidence of evolution.)
3. If the above argument states a significantly worse argument for evolution than are available, then the above argument does not refute the best reasons to believe in evolution.
4. Therefore, the above argument does not refute the best reasons to believe in evolution.

The map for this objection is the following:

(3) Appeal to authority

An appeal to authority argument is reasonable when we refer to the unanimous opinions of experts who have justified their beliefs though the appropriate research. The “appeal to authority fallacy” is when we refer to the opinions of others who are not qualified in the relevant sense. Either the authority figure is not the right kind of expert or the expert’s opinion is controversial among the other experts in the field.

An example of an appeal to authority fallacy is the following:

1. Aristotle was one of the greatest philosophers of all time who discovered formal logic.
2. Aristotle thought the Sun revolves around the Earth.
3. Therefore, the Sun revolves around the Earth.

The map for this argument is the following:

Although Aristotle was a great philosopher, astronomers now unanimously agree that the Sun does not revolve around the Earth.

We can explicitly object to an argument that uses a fallacious appeal to authority by pointing out why it’s fallacious—either the authority is not the appropriate kind of expert or the experts do not unanimously agree. For example, we can give the following objection to the fallacious argument above:

1. The above appeal to authority is fallacious unless Aristotle is an expert astronomer and his opinion is uncontroversial among the experts.
2. However, Aristotle’s opinion is now unanimously rejected by the relevant experts.
3. Therefore, the above argument is fallacious.

The map for this objection is the following:

Update (3/29/2012): I made some corrections.

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You might want to read “Finding and Examining Arguments” before reading this.

People tend not to explicitly state every premise their argument requires, and we can try to discover the hidden assumptions (i.e. “unstated premises” or “missing premises”). I will present three passages, identify the premises and conclusions, explain how we can find the hidden assumptions, and create argument maps for them.

Passage 1

[T]he care of souls cannot belong to the civil magistrate, because his power consists only in outward force; but true and saving religion consists in the inward persuasion of the mind, without which nothing can be acceptable to God. And such is the nature of the understanding, that it cannot be compelled to the belief of anything by outward force. Confiscation of estate, imprisonment, torments, nothing of that nature can have any such efficacy as to make men change the inward judgement that they have framed of things. (Locke)¹

Here Locke argues that the “civil magistrate” (i.e. government) should not be concerned with “the care of souls” (i.e. people’s religious beliefs) because the government can use force, but religious beliefs should be influenced though inward persuasion of the mind (i.e. arguments). Persuasion involving force (e.g. confiscation of wealth, imprisonment, and torments) would not be capable of giving us a genuine religious belief of the relevant kind.

The premises and conclusion of the argument can be listed as the following:

1. Governments can only persuade us using force.
2. Force can’t cause genuine religious beliefs.
3. Genuine religious beliefs are only caused by arguments.
4. Therefore, governments shouldn’t be concerned with our religious beliefs.

This argument is incomplete because the premises don’t prove the conclusion. They don’t say anything about what the government should or should not be concerned with. It is not entirely clear what the hidden assumption is, but it could be “Governments shouldn’t be concerned with religious beliefs unless they can cause genuine religious beliefs.” This premise seems charitable to Locke’s reasoning because there’s nothing very offensive about it. It seems innocent enough. We can then rewrite the argument with the hidden assumption as the following:

1. Governments can only persuade us using force.
2. Force can’t cause genuine religious beliefs.
3. Governments shouldn’t be concerned with religious beliefs unless they can cause genuine religious beliefs.
4. Genuine religious beliefs are only caused by arguments.
5. Therefore, governments shouldn’t be concerned with our religious beliefs.

The argument map for this passage is the following:

Passage 2

I have heard it asserted by some, that as America hath flourished under her former connection with Great Britain that the same connection is necessary towards her future happiness, and will always have the same effect. Nothing can be more fallacious than this kind of argument. We may as well assert that because a child has thrived upon milk that it is never to have meat, or that the first twenty years of our lives is to become a precedent for the next twenty. But even this is admitting more than is true, for I answer roundly, that America would have flourished as much, and probably much more, had no European power had any thing to do with her. The commerce, by which she hath enriched herself, are the necessaries of life, and will always have a market while eating is the custom of Europe. (Paine)²

This passage presents various objections to an argument. The argument that is being rejected is that America can only flourish if it’s dominated by Great Britain because it flourished under Great Britain in the past. We can write this argument as the following:

1. America flourished because it was dominated by Great Britain in the past.
2. Therefore, America can only flourish if it’s dominated by Great Britain.

We know that this argument is incomplete, so it’s missing a premise. The fact that America flourished under Great Britain in the past does not prove that America can only flourish if it’s dominated by Great Britain.

The missing premise can be found by realizing that this argument can use modus ponens (A; if A, then B; therefore, B.) So far the argument form is A; therefore, B. The missing premise is “If A, then B.”

A is “America flourished under Great Britain in the past” and B is “America can only flourish if it’s dominated by Great Britain.” Therefore, the missing premise is “If America flourished under Great Britain in the past, then America can only flourish when it’s dominated by Great Britain.”

We can now rewrite the argument with the missing premise as the following:

1. America flourished because it was dominated by Great Britain in the past.
2. If America flourished under Great Britain in the past, then America can only flourish when it’s dominated by Great Britain.
3. Therefore, America can only flourish if it’s dominated by Great Britain.

Thomas Paine then gives us three objections against this first argument:

The first two objections are almost the same. First, he argues that the reasoning of the first argument is fallacious because it would imply that children flourish from drinking milk rather than eating meat, so they should always drink milk and shouldn’t eat meat. Second, he argues that the reasoning of the first argument is fallacious because it would imply that the first twenty years of our lives tells us everything we need to know about how to flourish in the future.

The fallacious reasoning he has in mind to refute here is that whatever causes flourishing in the past will cause flourishing in the future. The assumption is that the first argument’s missing premise—If America flourished because it was dominated by Great Britain in the past, then America can only flourish if it’s dominated by Great Britain—can only be justified if we assume that “whatever causes flourishing in the past will cause flourishing in the future.” The two arguments are objections to that premise because they are counterexamples. If the premise were true, then it would be best for adults to drink milk rather than eat meat (and the first twenty years of our lives would tell us everything we need to know about flourishing in the future). However, (presumably) adults should not drink milk and can eat meat (and the first twenty years of our lives doesn’t tell us everything about how to flourish in the future).

We can now list the premises and conclusion of Paine’s first objection as the following:

1. The only reason to believe that “if America flourished under Great Britain in the past, then America can only flourish if it’s dominated by Great Britain” is if what causes flourishing in the past will cause flourishing in the future.
2. If whatever causes flourishing in the past will cause flourishing in the future, then adults shouldn’t eat meat.
3. It is false that adults shouldn’t eat meat.
4. Therefore, it is false that whatever causes flourishing in the past will cause flourishing in the future.

And the premises and conclusion of Paine’s second objection is the following:

1. The only reason to believe that “if America flourished under Great Britain in the past, then America can only flourish if it’s dominated by Great Britain” is if what causes flourishing in the past will cause flourishing in the future.
2. If whatever causes flourishing in the past will cause flourishing in the future, then the first twenty years of our lives will tell us everything we need to know about how to flourish in the future.
3. It is false that the first twenty years of our lives will tell us everything we need to know about how to flourish in the future.
4. Therefore, it is false that whatever causes flourishing in the past will cause flourishing in the future.

Third, Paine argues that America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain, so America would have flourished as much if not more without the domination of Great Britain. We should therefore reject the conclusion that America only flourished because it was’s dominated by Great Britain. This argument objects to the premise that “America flourished because it was dominated by Great Britain in the past.” The premise and conclusion of this argument is the following:

1. America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain.
2. Therefore, it is false that America flourished in the past because of the domination of Great Britain.

Again, we know that there’s a hidden assumption because the premise does not prove the conclusion to be true by itself. And once more we can use modus ponens to find the missing premise. A is “America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain” and B is “it is false that America flourished in the past because of the domination of Great Britain.” The missing premise is “If A, then B,” so the hidden assumption is “If America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain, then it is false that America flourished in the past because of the domination of Great Britain.” We can now write the argument with the hidden assumption as the following:

1. America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain.
2. If America has prospered because of commerce dealing with the necessities of life rather than by being dominated by Great Britain, then it is false that America flourished in the past because of the domination of Great Britain.
3. Therefore, it is false that America flourished in the past because of the domination of Great Britain.

When making an argument map for this passage, we need to keep in mind how exactly the objections relate to the first argument (and the justification given for it).

The argument map for the passage is the following:

Passage 3

We argued, as we thought then rather logically, that no social class was so good, so true, and so disinterested as to be trusted wholly with the political destiny of its neighbors; that in every state the best arbiters of their own welfare are the persons directly affected; consequently that it is only by arming every hand with a ballot,—with the right to have a voice in the policy of the state,—that the greatest good to the greatest number could be attained. To be sure, there were objections to these arguments, but we thought we had answered them tersely and convincingly; if some one complained of the ignorance of voters, we answered, “Educate them.” If another complained of their venality, we replied, “Disfranchise them or put them in jail.” And, finally, to the men who feared demagogues and the natural perversity of some human beings we insisted that time and bitter experience would teach the most hardheaded. It was at this time that the question of Negro suffrage in the South was raised. Here was a defenceless people suddenly made free. How were they to be protected from those who did not believe in their freedom and were determined to thwart it? Not by force, said the North; not by government guardianship, said the South; then by the ballot, the sole and legitimate defence of a free people, said the Common Sense of the Nation. No one thought, at the time, that the ex-slaves could use the ballot intelligently or very effectively; but they did think that the possession of so great power by a great class in the nation would compel their fellows to educate this class to its intelligent use. (DuBois)³

There are six major arguments contained in this passage.

The first argument states that social groups need a right to vote because no one social group can be trusted to look out for the welfare of other social groups and we know how to look out for our own social group’s welfare best. The premises and conclusion of the first argument is the following:

1. We can’t trust any group other than our own to look out for our group’s welfare.
2. We know how to best look out for our group’s welfare.
3. Therefore, every social group needs a right to vote.

This argument is missing a premise. We know that because of the rabbit rule—premises must contain all the terms mentioned in the conclusion. In this case voting is not mentioned in either premise. We can use a version of modus ponens to reach the conclusion. We can treat both premises as A and the conclusion as B. The missing premise is then “if A, then B” or “If we can’t trust any group other than our own to look out for our welfare and we know how to best look out for our group’s welfare, then everyone needs a right to vote.” We can now rewrite the argument with the missing premise as the following:

1. We can’t trust any group other than our own to look out for our group’s welfare.
2. We know how to best look out for our group’s welfare.
3. If we can’t trust any group other than our own to look out for our welfare and we know how to best look out for our group’s welfare, then everyone needs a right to vote.
4. Therefore, every social group needs a right to vote.

The second and third arguments are both objections to the belief that every social group should have voting rights. The first objection is that some people are ignorant and the second objection is that some people suffer from venality (corruption). The conclusion of both these arguments is that we should reject that all social groups should have a right to vote. Both these objetions are missing premises. We know this because of the rabbit rule. Neither premise mentions “voting,” but the conclusion does. We can complete both objections and find the missing premises by realizing that they can both use modus ponens. The missing premise in both cases is “if A, then B.” The first objection is therefore missing the premise, “If some people are ignorant, then some social groups shouldn’t have a right to vote” and the second objection is therefore missing the premise, “if some people are venal, then some social groups shouldn’t have a right to vote.”

We can then rewrite both the objections as the following:

Objection 1

1. Some people are ignorant.
2. If some people are ignorant, then some social groups shouldn’t have a right to vote.
3. Therefore, we should reject that all social groups should have a right to vote.

Objection 2

1. Some people are venal.
2. If some people are venal, then some social groups shouldn’t have a right to vote.
3. Therefore, we should reject that all social groups should have a right to vote.

DeBois then criticizes these objections. One, he argues that we can educate people, so we should reject the premise that being ignorant is a good reason to take voting rights from a social group). Two, he argues that we could put venal people in jail or disenfranchise them, so we should reject the premise that being venal is a good reason to take voting rights from a social group. Neither criticism explicitly lays out the objection and they are both missing a premise. The first argument is against the premise that “if some people are ignorant, then some social groups shouldn’t have a right to vote” and the second argument is against the premise that “if some people are venal, then not all social groups should have the right to vote.” Both premises can be found once we realize that they can use modus ponens. Both premises can use the form “if A, then B.” Therefore, the missing premise of the first criticism is “If we can educate people, then we should reject that ‘if some people are ignorant, then some social groups shouldn’t have a right to vote.‘” The missing premise of the second criticism is “if we can arrest or disfranchise people for being venal, then we should reject that ‘if some people are venal, then not all social groups should have the right to vote.’”

The premises and conclusion of the criticisms are the following:

Criticism 1

1. We can educate people.
2. If we can educate people, then we should reject that ‘if some people are ignorant, then some social groups shouldn’t have a right to vote.’
3. Therefore, we should reject that if some people are ignorant, then some social groups shouldn’t have a right to vote.

Criticism 2

1. We can imprison or disenfranchise people who are venal.
2. If we can arrest or disfranchise people for being venal, then we should reject that ‘if some people are venal, then not all social groups should have the right to vote.’
3. Therefore, we should reject that if some people are venal, then some social groups shouldn’t have a right to vote.

The sixth argument concerns how the welfare of black people should be protected. The North rejects the view that we should protect the welfare of black people with force and the South rejects that we should protect the welfare of black people with government guardianship. DuBois concludes that we should protect their welfare by giving them voting rights.

The premises and conclusion of the sixth argument are the following:

1. The welfare of black people should be protected.
2. The North won’t protect the welfare with of black people with force.
3. The South won’t protect the welfare of black people through government guardianship.
4. Therefore, black people should have voting rights.

However, we should notice that this argument is missing a premise. The premises are not sufficient to prove the conclusion to be true. One way we can realize this is because of the rabbit rule—the conclusion mentions a term (voting rights) that aren’t mentioned in the premises. One option here is to use a premise containing “either or”—We should either protect the welfare of black people by giving them voting rights, or through force, or though government guardianship. The argument with the missing premise now looks like the following:

1. The welfare of black people should be protected.
2. We should either protect the welfare of black people by giving them voting rights, or through force, or though government guardianship.
3. The North won’t protect the welfare with of black people with force.
4. The South won’t protect the welfare of black people through government guardianship.
5. Therefore, black people should have voting rights.

The argument map for the passage is the following:

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Notes

Filed under: philosophy Tagged: argument maps, argumentation, critical thinking, education, justification, logic, rationality, reasoning