Logical ReasoningDifficulty: Hard

PT129 S1 Q21 Explanation

Several people came down with an illness

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

TopicsParadox

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Stimulus

Several people came down with an illness caused by a type of bacteria in seafood. Health officials traced the history of each person who became ill to the same restaurant and date. Careful testing showed that most people who ate seafood at the restaurant on that date had not come in contact confident that contaminated seafood from this restaurant caused the cases of illness.

What this question is testing

Paradox

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence 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
21.

Which one of the following, if true, most helps to resolve the apparent

Answer choices

  1. Out of Scope: "immune"6% picked this

    Most people are immune to the effects of the bacteria

    Being immune to the bacteria is not the same as not coming into contact with it, so this couldn’t help us to explain that part of the mystery. If the paradox had been, “Given that most people came into contact with it, how come only several got the illness”, then this answer would work.

  2. Unclear Impact / Irrelevant Distinction18% picked this

    Those made ill by the bacteria had all been served by a waiter who

    We have no idea if the waiter also ate this seafood or even if the subsequent illness was the same as that suffered by the patrons. This also doesn’t help us explain why the majority of seafood eaters weren’t exposed to the bacteria.

  3. Opposite /Irrelevant: "allergic to MSG"12% picked this

    All and only those who ate contaminated seafood at the restaurant on that date were allergic to the monosodium glutamate in

    We were told that the sickness came from bacteria, not an allergy to MSG. So either this is saying, “the sick people ALSO had an allergic reaction” or it’s trying to contradict the given idea that the sickness came from ingesting a bacteria, not MSG.

  4. Explains Background, Not Surprise4% picked this

    The restaurant in question had recently been given a warning about violations

    This adds some context to why the restaurant might serve contaminated seafood, but it doesn’t help us explain why the majority of seafood eaters didn’t get exposed to the bacteria.

  5. Correct61% picked this

    All and only those who ate a particular seafood dish at the restaurant

    Why this is right

    This gets at the overly broad category of ‘seafood’ from the paradox. Most seafood eaters didn’t get the bacteria, but maybe all the people who ordered scallops got the bacteria. The keyword that distinguishes the sick group from the rest of the seafood eaters is a particular seafood dish. The bacteria could have been only found in the Scallops Au Gratin, and everyone who ate that got sick. Everyone who didn’t eat that dish, didn’t get sick (whether they ordered seafood or not).

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

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