LSAT 153 | Section 3 | Logical Reasoning: Q11

LR Question 11 Explanation

QUESTION TEXT: Studies have shown that those who take daily doses of vitamin C…

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: People who contract colds are likely not taking daily doses of vitamin C.

REASONING: People who take daily doses of vitamin C are less likely to contract colds than those who do not.

ANALYSIS: The flaw in the argument is that knowing the effects of vitamin C on catching colds does not tell us anything about the people who catch colds and their tendencies to take vitamin C. We can break down the argument to something like this.

If X, then Y is unlikely.

Therefore, If Y happens, then X is unlikely.

The fact that X makes Y unlikely doesn’t allow us to say the reverse, that Y happening makes X unlikely. For the parallel reasoning, we should be looking for two main components. The first will be that there will be one condition affecting the likelihood of another. The second will be the reversal of that likelihood equation, just as featured above.

___________

1. This has nothing to do with the components we are looking for. None of the components affect likelihood and there is no reversal.
2. This is a different error, it assumes that because one type of cafeteria food caused illness, then they all do.
3. Wrong kind of error. The mistake in this argument is that it assumes the effects of the low-calorie diets are the same for rats and people.
4. This argument mistakes one contributing factor for a result as being the sole cause.
5. CORRECT. This perfectly matches the mistake in the original argument. If we take “Oil changes” as X and “engine problems” as Y, then we can recreate our argument from before. X makes Y unlikely. Therefore, if Y happens, then X is unlikely.

Recap: The question begins with “Studies have shown that those who take daily doses of vitamin C”. It is a Flawed Parallel Reasoning question. Learn how to master LSAT Flawed Parallel questions on the LSAT Logical Reasoning question types page.