Logical ReasoningDifficulty: Medium

PT103 S1 Q8 Explanation

Based on data collected from policyholders,

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

TopicsNecessary Assumption

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Stimulus

Based on data collected from policyholders, life insurance companies have developed tables that list standard weight ranges for various heights. Policyholders whose weight fell within the range given for their height lived longer than those whose weight fell outside their given range. Therefore, if people whose weight falls fall within that range, their overall life expectancies would improve.

What this question is testing

Necessary Assumption

Your task

Find the assumption the argument requires in order for its conclusion to hold.

Common trap

Answers that would help the argument but aren't strictly required (sufficient, not necessary).

Winning move

Negate each choice — the right one breaks the argument when negated.

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

The question
8.

Which one of the following is an assumption on which the

Answer choices

  1. Out of Scope: unwilling1% picked this

    Some people would be unwilling to modify their weights solely to increase the general population’s

    This argument has nothing to do with claiming that people are willing to modify their weights. It's only saying that if they modified their weight, a certain result would follow.

  2. Out of Scope: companies' intent14% picked this

    Life insurance companies intended their tables to guide individuals in adjusting their weights in order to

    The author doesn't need to assume that life insurance companies intended their tables to be used the way the author is using them. I might use a world map to plan an invasion of Australia. That doesn't mean that the map maker intended for the map to be used to invade Australia.

  3. Weakens3% picked this

    The tables include data gathered from policyholders whose deaths resulted from accidents in addition to those whose deaths

    The author doesn't need to assume anything about the specifics of how the life insurance company puts together its table. But if the table includes deaths that result from accidents, that actually introduces some noise that calls into question the way the author is interpreting the correlation. An alternate explanation for the 2nd sentence could be, "People whose weight fell outside the standard range didn't live less long because their weight killed them; these people were more likely to die in an accident that killed them much earlier in life than natural causes would have."

  4. Irrelevant Comparison6% picked this

    Holders of life insurance policies do not have longer overall life expectancies than

    The author doesn't need to compare insurance policy holders to the general population. It doesn't affect the argument whether policyholders have shorter life expectancies, longer ones, or similar ones. The only logically relevant part of the policyholder table is the comparison between policyholders within weight range vs. not in weight range.

  5. Correct75% picked this

    People’s efforts to modify their weight to conform to a given range would not damage their health enough to

    Why this is right

    As we predicted, this answer rules out a possible objection. The author makes a prediction, and we could fight that prediction by saying that if people try to change their weight to get it in range, it will not increase their life expectancy. Whenever we're doing Necessary Assumption and we see an answer with "ruling out" language like not / no, we want to consider it. Tons of correct answers (the vast majority of Defender answers) have that feature. If we negate this answer, does it hurt the argument? "People efforts to modify their weight would damage their health enough to decrease their overall life expectancies" Yes, that definitely weakens! In this case, it basically contradicts the conclusion. The correct answer, when negated, will weaken the argument. In this case, it weakens it so much it basically refutes the conclusion!

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

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