Shantila's Inside Logic #25

Fallacies

*

You are going to leave soon in Britney's plane. The guy who was going to confess is sitting by the men's restroom, handcuffed to a chair after getting arrested for trying to steal Joe's lottery ticket. He looks at you plaintively. He seems so unhappy that you decide you should talk with him for a moment before leaving.

"Do you know where Shantila went?" he asks immediately.

"No," you say. "But I think she left you for good this time."

"Oh," he says.

"At least that's what she told me," you say.

"Well, I deserve it," he says.

"Why?" you ask.

"What happened is I wrote a textbook about logic but it had a dumb story in it," he says. "So when I passed it out and put it online I decided I'd better not use my real name."

"Hmm."

"So I made up a name. A pseudonym," he says.

"What name did you use?"

"Shantila." he says. "Shantila Hugginger."

"Oh."

"But it turned out there was a woman in Chicago already named that!"

"Her?" you ask.

"Yes, her. Shantila. After I put the stuff online and started using it for my class, she got fired from her job. Her boyfriend broke up with her. And her reputation was completely ruined."

"Just because you used her name?" you ask.

"Yes," he says. "When she first contacted me about it, she said she was going to sue me. But I don't have any money so that was going to be pointless. So I said how about we meet for coffee. The rest is history."

"I am so sorry!" you say.

"I basically ruined her life," he says. "Now she is going to leave the country."

"Wow. What a confession!" you exclaim.

"Oh," he says.

"What?"

"Actually, that's not the confession."

"What's the confession?" you ask.

"I am a university professor. I have been stealing money from my students," he says.

"No. I can't believe it," you say. "That is horrible!"

"I know," he says. "I have been doing it for many years."

"Wow," you say. "So you mean, like, they pay their tuition and come to class, but you don't teach very well? So you've been wasting their time? Is that what you mean?"

"No. Well, yes, probably I have been boring them pretty bad," he says. "But that's not what I meant."

"What did you mean?" you ask.

"I have actually been taking their money," he says.

"You've been taking their money?" you gulp.

"Yes," he says.

"That is stealing!"

"Yes, I know."

"But how do you get it?"

"I make them focus on logic problems so hard that I easily can walk around the class during tests and I simply reach into their backpacks and get the money."

"Wow."

"Actually that's the biggest thrill of logic for me. That is why I love proofs," he says.

"Wow," you say again. "That is really horrible."

"I know. I am very sorry about it," he says.

"Your students probably do not have very much money to begin with," you say.

"That's true," he says. "It is frustrating. I can get only about $20 per test and that is hardly enough for a movie if you buy popcorn and stuff."

A policeman suddenly walks out of the bathroom and unlocks the man from the chair. The cop lifts him up, and they walk away.

***

We earlier talked about inferences as processes of thought that often can be evaluated as good or bad. There is an area between formal logic and other areas of philosophy (such as epistemology, philosophy of science, and ethics) that classifies an inference as good or bad based upon an interpretation of the inference.

We saw earlier that it is important to be charitable in interpreting the reasoning of others. All the same, people definitely make bad inferences now and then. Recall, for example, the fallacies AC/Bad or DA/Bad that we criticized earlier. And sometimes people (knowingly or unknowingly) try to get other people to make bad inferences too. They are able to get away with this because most bad inference practices come disguised as corresponding good ones.

The bad practices that come disguised as good ones we call "fallacies," and they can be considered "near enemies" of the corresponding good forms of reasoning. The fallacies can be contrasted both with the corresponding good inference as well as with others that are simply and obviously bad, not even masquerading as good form. The non-masquerading bad forms we can call the "far enemies" of the good ones. For example, consider this chart about MP and AC/Bad:

Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")
Valid rule MP:

P>Q, P } Q

 Invalid form AC/Bad:

P>Q, Q } P

 Not only invalid, but ridiculous, for example, non sequiter:

P>Q, R } Q

Since AC/Bad might be confused with MP, it is possible for an invalid inference using AC/Bad to masquerade as MP. But inferences based on AC/Bad really are invalid, no matter what they look like -- they are just as invalid as the obviously invalid "just plain bad" and ridiculous far enemies.

We also can make a similar chart for MT and DA/Bad.

Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")
Valid rule MT:

P>Q, ~Q } ~P

 Invalid form DA/Bad:

P>Q, ~P } ~Q

 Just plain bad, for example:

P>Q, ~R } ~Q

*

Experts

Now to consider a different type of example, suppose my friend Sally is an expert on dinosaurs and has taught me a lot about dinosaurs. If I have a question about dinosaurs, I ask Sally and she gives me reliable information. There is nothing wrong with this. I have many reliable and interesting beliefs about dinosaurs because I rely on what Sally says about them. Reliance on experts is a source of knowledge. Small children learn a great deal about the world by relying upon the expertise of their parents and teachers about many things.

Now suppose you and I happen to be talking about logic. You tell me that AC/Bad is a not a valid argument form, but I say, Yes it is valid! You ask me, What are your reasons for saying that AC/Bad is valid? And I say, Because Sally told me so. Obviously my reliance on Sally is not wise in this context because (apparently) Sally is not an expert about logic even though she is an expert about dinosaurs. And my reliance upon her in this context would be unfortunate, since she happens to be wrong!

The fallacy of "appealing to authority" is using the authority of someone who is an expert in one area as a reason for regarding him or her as an expert in other areas in which he or she does not have expertise. Because Sally is an expert about dinosaurs, it might be tempting to assume she also is an expert about other things. And indeed, since she is smart enough to know about dinosaurs, it is likely that indeed she is smart enough to know about much else as well. But the assumption is dangerous. It is difficult for anyone to be an expert about very many things in a complex world. And it is simply impossible for anyone to be an expert about everything. (To consider a trivial example, nobody but you and perhaps one or two close friends or family members are experts about what you generally eat for breakfast.)

  Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")

  
  Reliance on experts (within expertise) Appealing to authority (outside expertise)

What are my reasons for saying that AC/Bad is valid? Because Sally told me so.

 Reliance on fools  

*

Character

Suppose now we are wondering if a certain person Sam really is an expert about topic X. How do we decide? Suppose, for example, Sam is a witness in court and topic X is about what happened when Joe shot the gun at the airport. Suppose it is controversial whether or not Sam is a reliable witness. It really matters. Suppose it then is shown that Sam lied in court in a criminal trial last year. This is relevant information about whether we should treat Sam as reliable now. But suppose someone says Sam's children do not like him. Well, even if true, this probably is irrelevant to the question whether or not he is a reliable witness. It is an irrelevant ad hominen attack. And obviously, if it is false and known to be false, then it is simply a malicious attack.

  Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")

  
  Relevant information about person (character witness) Ad hominem: irrelevant (even if true) information about a person, often negative

Sam's children do not like him. (This is a fallacy when this information is irrelevant to the topic being discussed.)

 Malicious slander: false negative claims about a person  

*

Generalizations

With respect to our own beliefs about the world, we as individual people have no choice but to accept the role of "expert" for our own lives. Nobody else has better information than you about all the details of your life. Based on our experiences, we form general beliefs about all sorts of things.

To consider an example we discussed earlier, one way or another one might come to have the general belief that all members of the BG dance team are conceited. How do we get general beliefs like that? Well, consider this example. Suppose we might meet somebody from Clearwater, Florida and find him or her to be quite annoying. The next day we happen to meet another person from Clearwater, Florida, and also find that second person annoying. On the third day, amazingly, we might meet yet a third person from Clearwater, Florida, and once again find that person annoying. After these three experiences, we might come to believe an "all"-statement about everybody from Clearwater, Florida. Everybody from Clearwater, Florida, is annoying. We can represent this belief using the symbols introduced earlier: (x)(C>Ax), using the symbols Cx: x is from Clearwater, Florida; Ax: x is annoying.

Now this belief might be reasonable. Notice that you can come to have such a belief even without meeting everybody who lives in Clearwater, Florida. We often do form general beliefs like this on the basis of a limited sample of things. A similar inference would be to the belief that Most of the people in Clearwater, Florida, are annoying. This is one form of "inductive" inference, and sometimes is rational.

On the other hand, sometimes we form such a belief too "hastily" -- being based on too small a sample. Or the sample might be too limited in some other way. Recall the story about the dreamy reasoning when you concluded that the couple at the airport was going to your sister's birthday dinner. You had some information that was relevant. They were going to a birthday dinner at the same general place and the same time as your sister's birthday dinner:

The Peachtree Plaza? A birthday dinner? At 6 o'clock tonight? -- My sister's dinner is at Atlanta's Peachtree Plaza at 6 tonight!! --These people must be going to my sister's birthday party!

What is being assumed here? That everybody going to a birthday dinner beginning tonight at 6 at the Peachtree Plaza is going to your sister's birthday party. This might very well be true. But equally it might be false, for there easily could be other birthday dinners taking place at 6 at the Peachtree Plaza (it is a large place). Your tendency to leap to the conclusion that they are going to your sister's party is influenced by your worries and excitement about going there yourself.

While it might not be stupid to make this inference in a situation like that, one has to be wary. The inference might be be a hasty generalization. In the first example, the inference to the belief that everybody in Clearwater, Florida, is annoying is based upon meeting only 3 people and it certainly is too hasty.-- It would be a case of "hasty generalization."

  Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")

  
  Inductive inference to "all"or "most" judgments based on enough good evidence Hasty Generalization based on a too few examples.

Everybody from Clearwater, Florida, is annoying.

Carelessly holding a generalization independent of any evidence (eg racial or sexual prejudice) -- no real generalization at all  

*

Two fallacies misusing the form of a valid argument

There are informal fallacies that, surprisingly, are based on arguments that are in fact valid. They are fallacies when they are presented as providing significant reasons for believing the conclusion, since in fact they do not do provide a significant reason for the conclusion.

  Good

inference

 Fallacy

("near enemy")

 Opposite

("far enemy")

  
  Presenting a valid argument in which the premises offer independent and significant support for the conclusion Begging the Question

Merely assuming what one wants to prove but pretending to have independent and significant supporting premises

Next week there is going to be an earthquake in Chile. Therefore, an earthquake will take place next week in Chile.

 Presenting an invalid argument as if it were valid  
  Ditto Equivocation

Using a name or phrase in more than one way

You live in Bowling Green. Bowling Green is in Kentucky. Therefore, you live in Kentucky.

 Ditto  

A blatant example of Begging the Question: "Next week there is going to be an earthquake in Chile. Therefore, an earthquake will take place next week in Chile." Now notice that this is a valid argument -- if the premise is true, the conclusion must be true. But obviously it is not a significant argument since the conclusion merely re-states the premise. There is not going to be a clear-cut criterion here for distinguishing "significance" of arguments. Recall the valid argument from Fox Mulder in an earlier chapter that was supposed to offer support for the conclusion that personal identity is not identity of a soul. Since the argument is valid, the conclusion is implicitly "contained" in the premises. Does Mulder "beg the question"? Well, one who disagrees with his conclusion might try to criticize the argument for doing so. But in any case it is not as blatant as the example just given about earthquakes in Chile.

Examples of Equivocation will tend to be less controversial since it can be made obvious and definite when one is using a name in more than one way. We have talked about this sort of example before. Suppose I try to prove to you that you live in Kentucky, as follows. You live in Bowling Green; Bowling Green is in Kentucky; Therefore, you live in Kentucky. The argument is valid. But if you live in Bowling Green, Ohio, and not in Bowling Green, Kentucky, the argument can be interpreted as sound only by interpreting the name 'Bowling Green' in two different ways -- as BG, OH in the first premise and as BG, KY, in the second premise. This is the fallacy of equivocation and it is possible because of the simple and obvious fact that any name can be used to refer to more than one thing. And, of course, this argument is not sound given a univocal (that is, not equivocal) use of the name 'Bowling Green' to refer to either BG, OH or BG, KY both times it is used. If BG, OH is intended, then the second premise is false. If BG, KY is intended, then the first premise is false (assuming, of course, that you live in BG, OH).

* Practice

25.1 The identification of fallacious reasoning requires interpretation within a certain context, and sometimes it is not totally clear cut when reasoning is fallacious. But assuming that each of the following is asserted or thought in a context in which it is fallacious, which fallacy (of those discussed in this chapter) is most clearly exhibited by each of these?

1. Noted psychologist Dr. Laura believes investing in gold is how to get rich fast, so that is what you should do.

2. You may argue that God doesn't exist, but you are just following a fad like you always do.

3. I got sideswiped by this Italian guy name Calvino and had to get my car repainted; all Italians are lousy drivers.

4. Father Dave's arguments against abortion are no good. He's a priest, so he has to say that abortion is wrong, and besides lots of priests have molested children.

5. She asserts that we need more military spending, but that is false, since she is only saying it because she works for a defense contractor.

6. Since I'm not lying, it follows that I'm telling the truth.

7. The sign says "Fine for parking here." The sign said it was fine, so you shouldn't be writing me that ticket, sir.

8. We know that God exists, since the Bible says God exists. What the Bible says must be true, since God inspired it and God never lies.

9. All of my friends are in favor of the federal tax increase, so the tax increase is very popular.

10. The great baseball player Rafael Palmeiro endorsed Viagra on tv, so you should get some right away.

11. The belief in God is universal. After all, everyone believes in God.

12. All men are all sexist pigs, which I know all too well since every one of my last four boyfriends turned out to be a sexist pig.

13. If such actions were not illegal, then they would not be prohibited by the law.

25.2 Create an example in English of each of these fallacies. (That is, come up with a new one that has not been discussed in the text or in class.)

(a) Affirming the Consequent (Bad/AC)

(b) Denying the Antecedent (Bad/DA)

(c) Appealing to Authority

(d) Ad hominem

(e) Hasty Generalization

(f) Begging the Question

(g) Equivocation