Saturday, November 10, 2012

Logical Lingo I

For the next few weeks, I am going to blog about some different logical terms and phrases, including the non sequitur, the red herring, and the straw man. For this blog, I will specifically explore the non sequitur.

You probably noticed the italicized font. I know the suspense is killing you.

Non sequitur is Latin for "it does not follow," and it has a colloquial meaning and a logical meaning.

Colloquially, it can mean that a person suddenly changes the topic of discussion. For example, take the following dialogue between two old colleagues:

Pete: I'm can't understand why gas prices are so high. Did you watch the news this morning?
Kate: Yeah.
Pete: Do you hear anything about a storm forming in the Gulf of Mexico--maybe the big oil refineries are threatened?
Kate: Mike just texted me. He just won $10 on a scratch off ticket.

In this dialogue, Kate's final two statements could each be colloquially classified as a non sequitur. The question that Pete asked her is ignored. Instead, she provides him with irrelevant information.

The logical definition is a little different than its colloquial one. In its most general connotation, given its etymology, I suppose it could mean several different kinds of fallacies. Any fallacy that prevents the proper movement from premises to conclusion could be considered a non sequitur.

In Nonsense, our friendly guide, the late Robert J. Gula defines it a little more narrowly: He writes: "A non sequitur is a statement that claims to make a cause-and-effect relationship when, in fact, there is no logical connection between the premises and the conclusion" (56).

Although this piece of logical lingo may be new to you. I'm sure you've been subjected to the reasoning process that it condemns. For example, let's imagine the following argument:

Premise 1: If you want to be a great basketball player, you need to have a lot of stamina.
Premise 2: In order for you to have a lot of stamina, you need to do a lot of strenuous cardiovascular activity.
Premise 3: XYZ is a pair of basketball shoes that look cool with any dark basketball uniform.
Conclusion: XYZ will make you a better basketball player.

The conclusion above is, according to Gula's definition, a non sequitur. Premise 1 is true. Premise 2 also seems true. Let's suppose that premise 3 is also true. Does the conclusion follow (or "logically connect") from these three premises?

In other words, when you move from the beginning of the argument to the end of the argument, do the terms or concepts contained in the premises move to the conclusion in a logically acceptable manner?

Perhaps another example will help to show what I mean when I ask whether the conclusion follows from the premises. Let's take a look at the following argument:

Premise 1: If I miss the bus, then I will have to walk to school.
Premise 2: If I have to walk to school, then I will be all sweaty during my class.
Premise 3: If I am all sweaty during my class, then I will not be able to concentrate on my professor's lecture.
Premise 4: I missed the bus.

What conclusion follows from these four premises? Well, it follows from premise 4 and premise 1 that "I will have to walk to school." What follows from this? Look at premise 2.

When we look at premise 2, we know that "I will be sweaty during my class" follows from "my walking to school." What follows from this?

Our conclusion: "I will not be able to concentrate on my professor's lecture."

Now let's go back to the example with the basketball shoes. I guess it's possible that the conclusion  is true, but its relationship to the premises is very loose, so loose, in fact, it is close to being irrelevant. Because it states a causal conclusion that does not logically follow from the premises, it is, if we use Gula's definition, a non sequitur.

When you write a paper that calls for you to make an argument, you should watch out for the non sequitur. It might help to look carefully at your conclusion. If you write a paper about vegetarianism and conclude that "eating meat causes obesity," be sure that your premises are specific enough to support the conclusion. If your premises are all about the cruelty that animals endure in order for people to eat meat, then your conclusion will be a non sequitur.

I'm sure you can imagine many instances where a speaker or a writer might use a non sequitur as a means to persuasion. What we need to remember is that given there fallacious character, an argument that employs a non sequitur should not earn our vote.

Looking at what I've written about non sequiturs it probably doesn't surprise you that they play a big role in comedy--both sketch comedy and the unscripted kind that takes place between you and friends. For example, take the following examples:

"Let's go get some lunch. I've got a taste for a pizza. What about you?"
"Do clowns get paid by the hour or are they salaried?"

"Vegetarians live longer than carnivores. Maybe you should stop eating meat."
"The Bears won last night. 28-13."

"Let's stop at that gas station up there, so I can get a lottery ticket. The jackpot is up to 300 million."
"Martin Scorsese's been married five times. That fifth time must've been awkward during the vow exchange."

All these short dialogues are, or at least attempt to be, comedic instances of non sequiturs. They may not be funny, but I hope they help you see the comedic potential of the non sequitur.

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