Logical reasoning PrepTest 146 · Section 1 · Question 22

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
A study had a sample that was too small to draw conclusions from, but it did show that younger subjects had less of a toxin, so a ban must have worked.

Answer Anticipation:
It's always interesting to see an argument that points out a potential flaw! Here, the stimulus establishes that the study in question had a sample that was too small to lead to "valid inferences"—gotta love recognition of a sampling flaw.

However, the argument then goes on to draw an inference from the results of the study! It states that the study "proves" regulations worked. You can't say a study has too small of a sample to draw an inference and then use it to draw an inference.

This argument contradicts itself in how it treats the study, so the correct answer should highlight this shift.

Answer Explanation:
The argument starts by treating the study as being too small to allow for inferences. It then inconsistently uses it to draw an inference. This answer reflects that shift and is thus correct.

Key Takeaway:
While rare, there are some examples of self-contradictory arguments on the LSAT. Make sure that the author of the argument is contradicting an earlier statement from their argument and not from an opposing point!

Incorrect. The study looked at the levels of the chemical in individuals, it didn't look at effects as a proxy for levels of the chemical. As such, multiple chemicals having the same effect wouldn't impact this argument.

Incorrect. The generalization in the conclusion is based on a study, not on a flaw in an opposing point attempting to disprove it.

Incorrect. It's hard to see how regulations banning a chemical could be the result of that chemical being used less. Reversed causality doesn't make sense in this case!

Incorrect. The ban was in the 70s and the study was done in 2005, so more than "several years" have passed since the ban. Additionally, the stimulus discusses PCB levels, not PCB effects.