Logical ReasoningDifficulty: Medium

PT9 S4 Q10 Explanation

Myrna: People should follow diets

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

TopicsNecessary Assumption

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Stimulus

Myrna: People should follow diets in which fat represents no more than 30 percent of total calories, not the 37 percent the average diet in this country contains. Roland: If everyone in the country followed your recommendation during his or her entire life, just 0.2 percent would lengthen their lives at all, high a price to pay for the chance of extending that sacrifice for 3 months.

Myrna: But for everyone who dies early from a high-fat diet, many more people suffer from serious chronic followed such diets.

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
10.

Roland’s argument assumes

Answer choices

  1. Opposite5% picked this

    it is desirable to live in such a way as to lengthen life as

    Roland actually says the opposite: it is not worth striving to extend life when the payoff is small. He is not assuming that it is always desirable to lengthen life “as much as possible.”

  2. Correct76% picked this

    a low-fat diet cannot readily be made appealing and satisfying to a person who

    Why this is right

    This has the lovable Defender "not". If we negate it, does the answer weaken? Sure! If we say that a low-fat diet can readily (i.e. "easily") be made appealing and satisfying, then where is the sacrifice? Roland’s discussion of a “lifetime of sacrifice eating an unappealing low-fat diet” shows he’s assuming that eating less fat must inevitably be unappealing. If, on the contrary, one could make that diet appealing, his argument that the tradeoff is too high would no longer hold.

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

  3. Too Strong: the only10% picked this

    diet is the only relevant factor to consider in computing influences on

    Just because diet is the only factor influencing length of life that's mentioned doesn't mean the author is assuming that diet is the only factor that influences length of life. This answer would be better if it said he assumes that "Life expectancy is the only relevant factor to consider in deciding whether to modify our diet"

  4. Opposite6% picked this

    the difference in tastiness between a diet in which fat represents 30 percent of total calories and one in which it represents

    Roland’s argument depends on there being a big difference (a “sacrifice”) in taste and appeal. This choice says the difference is “not noticeable,” which would undercut Roland’s “too big of a price to pay” angle.

  5. Irrelevant3% picked this

    not everyone in the country eats the

    Whether not everyone literally eats the “average diet” does not affect Roland’s argument that adopting the low-fat approach yields too little benefit. Roland’s claim involves the hypothetical scenario in which everyone adopts Myrna’s 30% recommendation.

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