Logical ReasoningDifficulty: Medium

PT116 S3 Q22 Explanation

Taking advanced mathematics courses should

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsParallel Flaw

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Stimulus

Taking advanced mathematics courses should increase a student’s grade point average, for, as numerous studies have shown, students who have taken one or more advanced mathematics courses are far more likely to have who have not taken such courses.

What this question is testing

Parallel Flaw

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
22.

The flawed pattern of reasoning in the argument above is most similar to that in which one

Answer choices

  1. Weak Match1% picked this

    Fur color is in large measure hereditary, for, as many studies have shown, black cats are more likely than others to have black kittens,

    This concludes that "genes cause fur color" (hereditary = genetic). Is there a correlation in the evidence that says "cats who had these genes were more likely than those who didn't to have a certain color fur"? No, not quite. Talking about a cat's offspring certainly conveys the idea of shared genes, but this isn't the same as presenting a correlation between supposed cause (genes) and supposed effect (fur color). Also, this correlation wouldn't be vulnerable to speculation of reverse causality (we wouldn't be able to argue that fur color caused the genes).

  2. Weak Evidence Match2% picked this

    Water can cause intoxication. After all, imbibing scotch and water, whiskey and water, bourbon and water, gin and water, and vodka

    The conclusion is causal, although it's less strongly worded than the original. "X should have an effect on Y" seems stronger than saying "X can have an effect of Y". The evidence is not a correlation between X and Y, though. That would have sounded like, "People who drink water are more likely than those who don't to be intoxicated". But, this definitely deserves points for being one of the funniest LSAT answer choices we'll come across.

  3. Weak Match6% picked this

    Eating a diet consisting primarily of fats and carbohydrates may cause weight gain in some people. Studies have shown that many

    The conclusion is causal but more weakly worded than the original (X may cause Y vs. X should cause Y). And the evidence isn't quite the same type of correlation. We would want to hear something more like, "People whose diet is mainly fats and carbs are more likely than people without such a diet to have gained weight". This just says "many obese people eat such diets". Cool, but many non-obese people also each such diets. A correlation reveals a clear asymmetry because of how it's phrased. Many people who don't have high GPAs take advanced math, but the correlation is saying "yes, but you're more likely to have a high GPA if you take advanced math".

  4. Correct72% picked this

    Buying running shoes should increase the frequency with which a person exercises, since those who buy two or more pairs of running shoes each

    Why this is right

    The conclusion is causal and has the same strength: buying running shoes should cause more exercise. The evidence is a correlation saying "people who are X are more likely than those who aren't to be Y". And this argument is definitely vulnerable to reverse causality objections (maybe exercising a bunch causes them to need to buy running shoes more often) or third factor objections (maybe wealthy people have more means to buy new running shoes and more disposable time to exercise).

    Skill tested: Parallel Flaw · how this choice captures the argument's function is the move to repeat next time.

  5. Not as Good as (D)19% picked this

    Reading to children at an early age should inspire them to read on their own later, since studies have shown that children who have

    This is a frustratingly close match, but not as close as (D). This does have a causal conclusion of the same strength as the original. We want the evidence to say "kids who have been read to are more likely than those who don't to read on their own later". The evidence basically does say that. It's presented in inverted format, but it's the same idea: "kids who haven't been read to are less likely". That slight difference would already award the victory of "closest match" to (D), but the other salient difference is that there's no way to argue reverse causality with this one, since it already has a chronology built in. In the original, we could object, "maybe they had a high GPA before they started doing advanced math". We (D), we can object, "maybe they started exercising more first, and then they needed more running shoes". But with this one, we can't say, "maybe they started reading on their own later in life before they were read to as a child".

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