Logical ReasoningDifficulty: Easy

PT130 S1 Q9 Explanation

People who need to reduce

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

TopicsFlaw

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Stimulus

People who need to reduce their intake of fat and to consume fewer calories often turn to fat substitutes, especially those with zero calories such as N5. But studies indicate that N5 is of no use to such people. Subjects who ate foods prepared with N5 almost invariably reported feeling hungrier afterwards more, quickly making up for the calories initially saved by using N5.

What this question is testing

Flaw

Your task

Describe the reasoning error the argument actually commits.

Common trap

Answers that name a real logical flaw the argument doesn't actually make.

Winning move

Articulate the gap in the reasoning yourself, then match it to the choice that describes that gap.

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

The question
9.

The reasoning in the argument is most vulnerable to criticism on the grounds that the argument fails to

Answer choices

  1. Too Weak / Opposite1% picked this

    many foods cannot be prepared with

    Since we're just debating whether N5 is useless or somewhat useful, it's not important whether it can be used to prepare all/not-all foods. We don't judge whether a tool is useful by asking, "Can I use this one tool to do all my household repairs?" This answer choice is also wrong because it goes with the author and strengthens the idea that N5 is useless.

  2. Opposite / Too Weak0% picked this

    N5 has mild but unpleasant side

    This goes the wrong direction. It sounds like a negative about N5. Our goal is to argue that N5 is useful (a positive). Furthermore, mild but unpleasant side effects is not a strong enough idea to move the needle, even if this were pointing in the right direction.

  3. Too Weak / Out of Scope:5% picked this

    not everyone who eats foods prepared with N5 pays attention to

    "doesn't pay attention to calories" This is such a weak claim, saying that there's at least one person who eats N5 foods but doesn't pay attention to how many calories they're consuming (his name is Jeff). We should be highly suspicious that such a weak idea could have much impact. But Jeff is actually irrelevant, since the conclusion says "N5 is of no use to such people". What kind of people? People who do pay attention to their fat and caloric intake.

  4. Irrelevant Comparison11% picked this

    people who know N5 contains zero calories tend to eat more foods prepared with N5 than do people who are

    It doesn't matter to us which group of people eats more N5 than another. We have to establish that there's some usefulness to eating N5. Hearing about people who eat it a lot doesn't prove that it's actually useful when it comes to reducing fat or calories.

  5. Correct83% picked this

    the total fat intake of people who eat foods prepared with N5 tends to decrease even if their

    Why this is right

    This shows how eating N5 could be useful to people who need to reduce their intake of fat and calories. They could use N5 to reduce their fat intake for some meals (they would end up having a normal amount of calories at these meals). A partial victory is still a useful step forward. Maybe they can achieve a total victory by using N5 at some meals to lower their fat and using some other means at other meals to lower their calories.

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

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