Logic 103: The Dark (Dark) Side of Logic

In response to requests from my logically-sound readers, you can now find links to Logic 101 (which covers the basic structure of logical arguments), and Logic 102 (which covers the Argumentum ad Baculum, Argumentum ad Hominem, Argumentum ad Ignorantiam, and Argumentum ad Misericordium) here.

Actual Article Begins Now:

All right, Logic fans, it is time for the next exciting episode in our cutting edge expose’ of the sneaky little fallacies which try to undermine the very foundation of dialogue as we know it. Last session, we talked about four of the most common fallacies at large in the world today: the Argumentum ad Baculum (where you threaten folks with evil things if they don’t agree with you), the Argumentum ad Hominem (where you call someone else evil in order to undermine their credibility), the Argumentum ad Ignorantiam (where you say something’s true because it hasn’t been proven untrue), and the lousy, low-down Argumentum ad Misericordium (where you say someone should agree with you because you are so pathetic). We also covered a bit about how to get goth girls to talk to you, because that seemed to be very relevant. Speaking of relevance, all these fallacies were revealed to be “fallacies of relevance”, because they address situations where the premises you are using to prove your conclusion are irrelevant to the actual argument.

Everyone clear? All right. We are ready for our next foray into the treacherous waters of logical argument:
The Dark (Dark) Side of Logic.

My Mom (again, with me as translator):

There are a few more common types of arguments that contain fallacies of relevance. Let’s take a look at them, before we move on into other types:

5. An Argumentum ad Populum (appeal to the people) is a fallacy that happens when someone tries to get others to agree with them by claiming that lots of other people do. This is something that advertising firms have brought to a fine art. We can also use it on the goth girl in the corner. When asked by the girl of your dreams exactly why she should go home with you, you can simply answer “You see all those goth girls in the corner over there? They all have.”
On second thought, probably better not.
However, we are often confronted by this kind of logic when we see commercials on t.v. or pictures of rallies posted by activist groups.
“Ten thousand people marched to show their support of the ‘More Sugar’ bill proposed by Senator Toothache. This is obviously a fantastic bill, given the massive support it has received!” By making people watching think that everybody supports the bill, that it is a thrilling work of legislature, the presenters appeal to everything BUT the viewer’s ability to reason and their common sense regarding whether or not this is a bill that will truly be worthwhile.

6. An Argumentum ad Verecundiam (appeal to authority) is a fallacy that occurs when someone appeals to the feeling of respect people have for the famous to win a conclusion. This type of argument is not always strictly fallacious, for a reference to the opinion of an admitted expert in his special field may, indeed, constitute relevant evidence. However, a famous scientist’s opinions about politics are not relevant to a political dispute. Neither is an appeal to a religious document, like the Bible, relevant to a question of science. Advertisers use the appeal to authority when they get testimonials from famous athletes or actors to try to convince people to buy some product, even when the product is not related to the fields of athletics or acting. The goth girl may try it out on you when she says “Robert Smith says that people can never really know another. Therefore, it is true that I will never know you.”

7. A special case of fallacies of irrelevance is the Petitio Principii (or begging the question) fallacy. This is a fallacy where the conclusion that is being argued is actually built in (usually in some hidden fashion) to one of the premises. For example, suppose we have the following apparent argument:
People with good taste in literature prefer Shakespeare to Tom Robbins. If more people with good taste in literature prefer one author over another, then the preferred author is the greater writer. Therefore, Shakespeare is a greater writer than Tom Robbins.

On the surface, this appears to be a valid form of argument. However, if we then ask the person offering this argument how you tell that someone HAS “good taste in literature,” we might well discover that he defines someone with good taste in literature as someone who prefers Shakespeare to Tom Robbins. In other words, he has built the conclusion into his first premise. This is the fallacy of begging the question.

Some other types of common fallacies can be kind of funny…

8. Let us consider the fallacy of the Complex Question. You may have heard some of these offered more or less as jokes:

Have you given up your evil ways?

Have you stopped beating your wife?

Such questions assume that a positive answer has already been given to a prior question that was never even asked. For example, in the first instance, the question might be “Have you ever in the past followed evil ways?” and to the second it would be, “Have you ever beaten your wife?”

Less amusing examples of this sort of question occur when, for instance, in a movie you see a cop browbeating a man arrested on suspicion of robbery. Instead of asking the man if he commited the crime, the cop in the movie might say, “What did you do with the money you stole?” The policeman in this case is committing the fallacy of the Complex Question by PRESUPPOSING that he and the suspect have already agreed that the suspect did, in fact, commit the robbery.

Even sneakier examples occur in everyday conversation, however, involving question-begging labels. For example, you might be asked, “Is so and so one of those screwball radicals?” Or, conversely, “Is so and so a damned kneejerk conservative?” Or, about a proposed piece of legislation, “Is this policy going to lead to ruinous taxes for the middle class?” Obviously, the only way to deal with such questions is to divide the complexity into simpler questions. One might answer the first by saying, “Somewhat of a radical, yes, but not a screwball.” To the second, “He is a conservative on most issues, yes, but not in any kneejerk, automatic fashion.” On the third, the answer might be, “Yes, it will lead to slightly higher taxes, but not only on the middle class and not to a ruinous extent for anyone.” A good bit of political advertising these days makes use of such complex epithets.

Then, of course, we have our ongoing discussion with the pretty goth girl in the corner:

She says: “Does your girlfriend know you are out using fallacious arguments to try to pick up other girls at bars?”
You Answer: “No! Of course I would never use a fallacious argument!”
But she’s already gone…and you forgot to address the fact that you don’t have a girlfriend.

9. The Ignoratio Elenchi (or irrelevant conclusion)fallacy happens when an argument which is supposed to establish one particular conclusion is directed to proving a different conclusion.

For example, imagine a case where a young woman is on trial for murder. The prosecuting attorney might go on at length about the fact that murder is a horrible crime. He might even succeed in proving that conclusion. But when he infers from his remarks about the horribleness of murder that the defendant is guilty of it, he is committing the fallacy of ignoratio elenchi. Unfortunately, if the prosecutor has been really convincing, the jury may be so worked up that they will bring in a verdict of guilty faster than if the prosecutor had “merely” proved that the defendant had committed the crime.

10. Fallacies of Ambiguityare a type of fallacy where the arguments contain ambigious words or phrases, whose meanings shift and change in the course of an argument, and thus render it fallacious. One such fallacy involves what is called “equivocation.” For example, the world “end” can mean either “goal” or “last event.” Now, consider the following classical example of a fallacy of equivocation:

The end of a thing is its perfection. [Here, “end” means “goal.”]
Death is the end of life. [Here, “end” means “last event.”]
Hence, death is the perfection of life.
This is an example where the person arguing has probably confused himself, simply by not distinguishing between the two meanings of the word “end.”

Here is another, more amusing example of the fallacy of equivocation:

Some dogs have fuzzy ears.
My dog has fuzzy ears.
Therefore, my dog is some dog!
11. The Fallacy of Composition : Another sort of fallacy is based on confusion between what we call the “distributive” and the “collective” use of general terms.

Consider the argument that since goth girls wear more black than most people, goths girls(totally) own more black clothing than all the people (totally). It is true that goths (each one individually or distributively) wear more black than most people do (individually). However, this is an invalid argument. There are many more non-goths than goths, so that goths (totally or collectively) own less black clothing all together than everyone else put together. A similar mistake would be made in arguing, for example, than since an individual beer is relatively light in weight, a pallet of beer is also light in weight. You can easily carry a single beer to the party; but can you carry a pallet worth of beer anywhere?

12.The exact opposite sort of argument is called a Fallacy of Division. This involves arguing that what is true of a whole must be true of its parts. You might, for example, argue that because a pallet of beer is heavy, each beer must be heavy. More difficult examples of the fallacy of division, however are harder to catch. For instance, consider the perfectly valid argument:

Dogs are carnivorous.
Japanese spaniels are dogs.
Therefore, Japanese spaniels are carnivorous.
Then consider this argument, which closely resembles the valid one:

Dogs are common.
Japanese spaniels are dogs.
Therefore, Japanese spaniels are common.
This argument is invalid, because is commits the fallacy of division; it assumes that because of the fact that dogs in general are common (occur frequently almost everywhere) that a particular type of dog is also common (occurs frequently almost everywhere). This is obviously not true – in fact, I have never knowingly seen a Japanese spaniel.

Again, remember the valid argument we discussed in our first session:

All people will eventually die.
I am a person.
Therefore, I will eventually die.
and compare it with this superficially similar argument:

Goth Girls are disappearing.
That girl is a Goth Girl.
Therefore, that girl is disappearing!
The fallacy of division strikes again.

Back to (Just) Me:

All right. We now have the low-down on the common types of fallacies at large in the world today. We looked at the Argumentum ad Populum, where it is claimed that because lots of people support something, it must be true. We investigated the Argumentum ad Verecundiam, where you try to bring in someone famous who knows nothing about the topic to back you up and say it’s true. Then we witnessed the nefarious Petitio Principii (where you try to tuck in your conclusion as one of your premises) and the Complex Question (where you wrap an assumption up in a question as if it has already been answered). We explored the sneaky Ignoratio Elenchi (wherein you prove one conclusion…but not the one you say you are) and the Fallacies of Ambiguity, where you get the various meanings of a word mixed up in your argument. Last of all we looked at the Fallacy of Composition and the Fallacy of Division, which try to claim that some parts are equal to the whole, and that what is true of the whole must be true of all its parts, respectively.

Whew! That’s a lot of fallacies. No wonder people are confused. But looking at them one by one, it’s easy to see where people get off track. Again, I offer up that if anyone can find and post examples they encounter of these (or any of the previous) fallacies that they encounter in real life, I will send you a lollipop. I promise. Give it a go, and see what you can come up with.