Logical ReasoningDifficulty: Hard

PT126 S1 Q24 Explanation

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

TopicsFlaw

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Stimulus

Advertisement: Researchers studied a group of people trying to lose weight and discovered that those in the group who lost the most weight got more calories from protein than from carbohydrates and ate their biggest meal early in the day. So anyone who follows our diet, which provides more calories from protein the biggest meal of the day, is sure to lose weight.

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
24.

The reasoning in the advertisement is most vulnerable to criticism on the grounds that the advertisement overlooks

Answer choices

  1. Out Of Scope Comparison3% picked this

    eating foods that derive a majority of their calories from carbohydrates tends to make one feel fuller than does eating foods that derive a

    Out Of Scope Comparison: “make one feel fuller” We’re not concerned with what type of food makes you feel fuller. This won’t help us argue that “#1 protein / early big meal” will not be sure to make you lose weight. At its best, maybe this answer gives someone a way to argue that a different diet might make it even easier to lose weight, but the conclusion is not comparative so that’s not a relevant objection.

  2. Too Weak: "a few"5% picked this

    a few of the people in the group studied who lost significant amounts of weight got nearly all of their calories from carbohydrates and

    It doesn’t hurt the author if people who used an opposite technique (#1 carbs / late big meal) also had some weight loss. The author will still say, “Yes, but the ones who lost the most weight were #1 protein / early big meal.” In most statistics / study results that LSAT presents, we come away with a tendency that two things were connected. We can’t weaken that evidence by pointing out that some data points did not follow that trend. It is a weak idea that is fully compatible with the original premise.

  3. Unclear Impact26% picked this

    the people in the group studied who increased their activity levels lost more weight, on average, than those who did not, regardless of whether

    Very tempting. This suggests that the author has pulled out the wrong causal factor from the study. It looks like activity level was a strong predictor of weight loss, whether or not people got #1 calories from protein or carbs. It has unclear impact on the conclusion, though, because the conclusion isn’t saying that #1 protein + early big meal is the best way to lose weight or the way that helps you lose the most weight. There’s nothing comparative about the conclusion, so the only way to beat the conclusion is to find a way to argue that if you did #1 protein + early big meal you would not necessarily lose weight.

  4. Correct64% picked this

    some people in the group studied lost no weight yet got more calories from protein than from carbohydrates and ate their biggest

    Why this is right

    It’s very rare for an answer this weakly worded to be correct on Weaken, but a weak idea can still be devastating if you’re arguing against a strongly worded claim. If I say that “All men like football”, you can completely refute me with one man who doesn’t like football. Similarly, we can refute the conclusion that “anyone who follows this diet is sure to lose weight” with one counterexample of someone who followed the diet but didn’t lose weight. That’s what this answer provides. Even though “protein > carbs / early biggest meal” was associated with those who lost the most weight, it was also associated with people who lost no weight. Thus, it’s very hard for the author to act in her conclusion like following these two guidelines ensures that anyone will lose weight.

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

  5. Opposite2% picked this

    people who eat their biggest meal at night tend to snack more during the day and so tend to take in more total calories

    This seems to strengthen by supporting the author’s notion that eating big earlier in the day would lead to weight loss, by adding that it results in less snacking.

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