Logical reasoning PrepTest 116 · Section 3 · Question 22

Incorrect. Reversed causality doesn't even make sense in this context—fur color can't cause particular genes! The conclusion also isn't comparative ("increase").

Incorrect. The conclusion here isn't comparative, so it's missing that aspect of the flawed reasoning. Additionally, while it's a good idea to drink water after drinking five different liquors, intoxication doesn't cause you to drink that water! (Also, it's a bad idea to mix five different liquors . . . Don't drink and LSAT, folks.)

Incorrect. The conclusion here is too weak in stating that something may" be a cause, whereas the stimulus said that it is an expected cause ("should increase").

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Flawed Parallel Reasoning

Stimulus Summary:
Students taking advanced math have higher GPAs than students who don't, so taking such a course should increase someone's GPA.

Answer Anticipation:
[S]hould increase" is a huge indicator of the flaw in this argument. Saying that one thing "should increase" another is saying that it should have a positive effect. In other words, this conclusion is causal! The advanced math courses are the supposed cause, with an increased GPA being the supposed effect.

Is that based on a correlation? It is—students with the supposed cause are "far more likely" to have a high GPA. "More likely" is correlative language, and so we have a correlation/causation flaw.

However, we can be a bit more specific.

First, the supposed effect isn't actually in the correlation. That effect is an increased GPA, whereas the correlation is about a higher GPA. That's a subtle shift that we should look for in the correct answer (it's the difference between comparing something to others and to itself over time).

Second, we can figure out the specific type of correlation/causation flaw here. And this correlation isn't likely a coincidence. Rather, it's likely the case that better students are more likely to take those advanced math classes—in other words, the argument gets the causality backwards.

Answer Explanation:
This answer has the two pieces of the flaw we identified. It goes from a correlation between buying running shoes and running to a conclusion that buying running shoes causes one to run, whereas the reverse makes at least as much sense. And it goes from a comparison between groups (runners vs. non—runners) to one within the group (someone before they buy running shoes to after; "should increase").

Key Takeaway:
For harder Flawed Parallel Reasoning questions that feature a flaw with a few different "types, the correct answer will need to match the subset of the flaw that the stimulus falls into. Additionally, trap answers will likely have the same flaw category but not the same type of flaw within that category. Here, we saw a couple correlation/causation flaws, but only one that had the same specific issues within that category as the stimulus.

Incorrect. First, a bad reason to eliminate this answer—the correlation is negative instead of positive. The reason we can't eliminate an answer based on this is that correlations work in both directions—if kids who aren't read to are less likely to enjoy reading later, then it's necessarily the case that kids who are read to are more likely to enjoy reading later. Otherwise, the comparative language in the correlation makes no sense. So what does let us eliminate this answer? The conclusion, which has two issues. First, it isn't about an increase in an effect, but rather about that effect being present (inspire"). Second, the causal relationship is different because there are different people involved (the person reading to the kid is the cause; the kid reading is the effect—versus the person taking the class as both the cause and that person's GPA increasing as the effect) and there's a timeline jump in it.