Logical ReasoningDifficulty: Hard

PT155 S2 Q15 Explanation

Few, if any, carbonated beverages

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

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Stimulus

Few, if any, carbonated beverages contain calcium. Some very popular ones, however, contain significant amounts of caffeine, and consuming caffeine causes people to excrete significantly more calcium than they would otherwise. Interestingly, teenagers who drink large amounts of carbonated beverages containing caffeine tend to suffer more broken bones than those who do who consume carbonated beverages with caffeine is probably due primarily to caffeine consumption.

What this question is testing

Weaken

Your task

Find the choice that makes the argument's conclusion less likely to be true.

Common trap

Answers that look negative but attack a claim the argument never relied on.

Winning move

Find the assumption the argument depends on, then pick the choice that undermines it.

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

The question
15.

Which one of the following, if true, most weakens

Answer choices

  1. Correct47% picked this

    Teenagers who drink large quantities of carbonated beverages containing caffeine tend to drink smaller quantities of calcium-rich beverages

    Why this is right

    This gives us a Third Factor alternate explanation. It's not the caffeinated soda that's causing these teens to have lower calcium and more brittle bones than their peers, it's the fact that they drink smaller quantities of calcium-rich beverages. You have teens drinking Mountain Dew, and other teens drinking milk. This answer is saying that the primary reason the Mountain Dew kids have more broken bones isn't that their MTN Dew drains their calcium but rather that they didn't have a milk-boosted supply of calcium to start with. Technically, we know the caffeinated soda drinking still contributes to lower calcium, but we now have a way to argue it's not the primary reason for their broken bones.

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

  2. Wrong Comparison29% picked this

    Teenagers engage in the types of activities that carry a high risk of causing broken bones much more often than both

    For this to be out answer it would need to say "Teenagers who drink caffeinated sodas engage in more broken bone activities than those who don't."

  3. Too Weak12% picked this

    Some teenagers have calcium deficiencies even though they do not consume

    The word "some" is wrong at least 90% of the time you see it in Strengthen, Weaken, Paradox since it's so weak. This says that there is at least one teenager who has a calcium deficiency even though they don't drink coffee. Cool. His name is Jeff, and he's sitting right here. "Sorry, Jeff, but you're irrelevant to this argument". Arguments about correlations and averages leave plenty of room for exceptions, but LSAT always writes this type of trap answer to bait people into objecting, "But that's not true 100% of the time!" You're right, but the author agrees with you. The author never said it was 100% of the time.

  4. Irrelevant Comparison: popularity Too Weak1% picked this

    Some of the less popular carbonated beverages contain even more caffeine than the

    This is again super dubious given that it says "Some". There's no impact on this argument by saying, "There is at least one less popular caffeinated soda that has even more caffeine than more popular ones". How does that help us argue that caffeinated soda is not the primary reason that teens who drink caffeinated have a higher rate of broken bones? Saying that "some brands have even more caffeine" doesn't allow us to think "oh, the brands that the teens are drinking don't REALLY have caffeine".

  5. No Impact10% picked this

    The more calcium a person ingests as a regular part of his or her diet, the more calcium that

    The more water I drink, the more I'll pee. What does this have to do with assessing the putative causal connection between caffeinated soda and broken bones? The people who make more money, spend more money, but they still end up with more money than the person who was low on money to begin with. So people who eat more calcium excrete more calcium, but still end up being someone with higher calcium (we assume).

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