Flawed Reasoning in LSAT Logical Reasoning Questions: Circular Reasoning

LSAT Logical Reasoning | LSAT Prep

LSAT Logical Reasoning, PowerScore LSAT Bibles[Click here to read Flawed Reasoning in LSAT Logical Reasoning Questions: Source Arguments]

Before we continue with our examination of common flaws found in LR questions on the LSAT, let’s take a brief moment to review why it’s so important to understand these argumentative errors. Here’s how I began the first post in this series, where we looked at Source Arguments:

Considering the vast majority of LSAT Logical Reasoning questions will have an argument in their stimulus, and the vast majority of those arguments will contain some sort of flawed reasoning, I thought I would take a moment to address a variety of the flaws that tend to appear with some frequency. In a series of posts I’ll examine a number of common mistakes that authors on the test make, which should prove useful for both Flaw in the Reasoning questions (a type that accounts for about 15% of all LR questions), as well as other question types that require you to respond to argumentation.

With that in mind, let’s turn our attention to another type of mistake that authors make with some frequency: Circular Arguments. Occasionally referred to as “circular reasoning,” these arguments commit a singular, recognizable error where the author’s stated conclusion (belief) is supported primarily, or even exclusively, by a premise that is the same as the conclusion. In other words, the author assumes as true (gives the premise as a truth) what is intended to be proven (the conclusion). This is a somewhat tricky idea to grasp in the abstract, so let me give you a simple example of what this might look like:

“The New England Patriots are the best football team because they’re better than the other teams.”

Do you see the restatement of just one idea in both the conclusion and its premise? Remember, when constructing an argument the author gives the premises as factual and then from those facts attempts to draw a valid, fully supported conclusion. So the conclusion must follow from the premises. But if I’m trying to prove that “the Patriots are the best,” I need to provide actual evidence for that belief, rather than simply saying it’s true in a premise as well. And that’s how circular reasoning works: the conclusion given is based on an identical premise, which the author simply believes without evidence. The “circularity” is based on the idea that when you question the conclusion the author points to the premise (the same idea), and when you question the belief in that premise the author just gives the conclusion (same idea again), and so on, around and around without any actual evidence to show the truth of either.

See if you can spot the circularity in another example:

“I must be telling the truth, since I’m not lying.”

How would you know I’m telling the truth? Well, according to me in this example, it’s because I say I’m not lying. But you would have no more reason to believe that premise (not lying) than you would to believe the conclusion (telling the truth), and vice versa.

If you spot an argument where the conclusion is synonymous with one of the premises, and no evidence has been given to show that the premise is correct/true, you’ve got a circular argument. At that point you can quickly scan the answers for one that describes the author presuming to be true the thing he/she is attempting to prove.

Here are a few examples of how the test makers describe circular reasoning:

“it assumes what it seeks to establish”

“presupposes the truth of what it sets out to prove”

“it takes for granted the very claim that it sets out to establish”

Notice in each of these the author mistakenly believes something to be true in a premise, when it is that very thing he/she is attempting to prove in the conclusion.

A final point about circular arguments: because most test takers don’t really understand what a circular argument is, answer choices like the ones above are very commonly presented as traps following stimuli with other reasoning errors. That is, you’ll see circularity described as the flaw much more often than you’ll see circularity actually appear in the stimulus. People pick this answer choice because they don’t truly know what it means, but don’t make that mistake! Only if you see the restatement idea discussed above should you choose an answer choice that suggests circular reasoning.

Keep an eye out for additional posts addressing a wide variety of other flaws you are likely to encounter on test day. Commit them all to memory and you’ll find yourself well prepared to respond to nearly any argument you come across.