The Typical Argument Types Typically Go Wrong on the LSAT

Describe questions (questions that ask of an argument’s “method of reasoning” or how the argument “proceeds”) have kind of a funny place on the LSAT. On the one hand, they’re not terribly common. You might see a couple on test day, or you might just as easily not see any at all. But the skill they test, describing reasoning with the subject matter abstracted out, is important to a lot of things on the LSAT.

Therefore, in class, when we talk about Describe questions, we also take the opportunity to go over the common types of arguments you’ll see on the LSAT. These aren’t just for Describe questions! You’ll see them other places, too. For example, Parallel questions are pretty much just Describe questions looking through a funhouse mirror.

But for today, we’re going to look at how some of these methods of reasoning relate to common flaws in arguments. There’s a lot of overlap between Describe questions and Flaw questions. Both kinds of questions involve describing the reasoning in arguments; the difference lies mainly in whether the reasoning described needs to be flawed. For many of the common methods of reasoning you’ll see in Describe questions, there are ways that reasoning can go wrong.

Ruling out options / Exclusivity

Arguments that proceed by ruling out options can be valid or flawed. It usually depends on whether the options presented are known to be exhaustive. Let’s take an example:

We’ll stop for dinner in Tumbleweed. We’re no longer welcome at the Cowboy Corral, so we’ll have to go to Fred’s Feed Trough.

That’s an argument by ruling out options: we don’t like one place, so we’ll go to the other. As written, it also commits a bad exclusivity fallacy — could there be other places to eat in Tumbleweed? We could fix this argument by adding a premise that the Cowboy Corral and Fred’s Feed Trough are the only places to eat in Tumbleweed. We’d then have a valid argument by ruling out options.

Analogies / Well, bad analogies

Arguments by analogy are inherently suspect. They typically argue that, since things are similar in one way, they must be similar in some other way. For example, you could reason that since Los Angeles and San Francisco are both coastal cities in California, they must have similar weather. That would be a bad conclusion. Arguments by analogy ignore relevant differences between the things being compared.

Some analogies are better than others. Some might even be reasonable. But it’s a hard to prove anything by analogy. Lots of Describe questions with arguments by analogy could just as easily have been written as Flaw questions. In some cases you’d only need to change the prompt.

Attacking a premise or assumption / Absence of evidence

Many Describe questions involve two perspectives; the task is to describe how the second perspective attacks the first. One common way the second perspective will respond is by attacking the first perspective’s premises or reasoning.

There’s nothing inherently wrong about doing this. If someone’s argument relies on faulty information or reasoning, then they should be called out for it. But take it just a little too far, and you’ll commit a fallacy. A bad argument shouldn’t persuade you of its conclusion. But that doesn’t mean its conclusion is false. If you make that little leap too far, you’ll commit an absence of evidence fallacy.

This is a flaw you’ll see in some Flaw questions, but it’s also one the LSAT tries to tempt you into making all the time. Many wrong answers on Soft Must Be True or Disagree questions, for example, try to trick you into going too far and attacking a conclusion.

Appeal to authority / Perception vs. reality

Some arguments in Describe questions cite an expert opinion to make their case. Even qualified experts can be wrong, so these arguments are usually not completely valid even at their best. That’s where issues of perception vs. reality creep in.

It gets even worse, though, when the experts become the wrong experts. If you ask me, your LSAT instructor, for advice on the bar exam, well, you’ve asked the wrong expert. Any conclusions you draw from what I said would therefore be very flawed.

There’s more, too. The ways arguments are reasoned are intimately intertwined with the ways they can go wrong. Keep your eye out for the methods of reasoning you learn about as you cover Describe questions. You’ll see them, done well and (more often) poorly, all over the LSAT.

One Response

  1. This is a really interesting observation. The argument types do tend to get used in a lot of different question types. I’ve notice that many necessary assumption stimuli could easily be turned into flaw questions with a different question stem (and different answer choices, of course).

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