Logical ReasoningDifficulty: Hard

PT144 S2 Q18 Explanation

An article claims that many medical

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

TopicsNecessary Assumption

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Stimulus

An article claims that many medical patients have an instinctual ability to predict sudden changes in their medical status. But the evidence given is anecdotal and should not be trusted. The case is analogous to empirically disproven reports that babies are born in disproportionately high numbers during full moons. Once that rumor remember busy nights with full moons than busy nights without them.

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
18.

The argument requires the assumption

Answer choices

  1. Too Strong: soon disproven20% picked this

    the article claiming that medical patients can instinctually predict sudden changes in their medical status will

    This is tempting, but the author doesn't specifically need this similarity to line up. The author is definitely assuming that in both cases "the claim" is not legit. In the case of "full moon babies" is was empirically disproven. In the case of "clairvoyant patients" it may one day be empirically disproven, but it doesn't matter to the author whether that happens soon or not.

  2. Correct58% picked this

    patients' predictions of sudden changes in their medical status are less likely to be remembered by medical staff if

    Why this is right

    This is a relevant similarity, selective memory. The author thinks that what gave credence to the false idea of "full moon baby explosions" was the selective memory that maternity room staff had --- they were more likely to remember busy baby nights that conformed to the full moon legend than to remember busy baby nights that deviated. So, similarly, the author is thinking that what gives credence to the false idea of "patients can predict what's going to happen to them" is selective memory on the part of the medical staff -- they are more likely to remember times when patients did accurately predict a change in status, and less likely to remember when patients didn't. If we negated this, it would break down what the author thinks is the crucial similarity between the two analogous cases. That said, this answer and this problem are frustratingly loose. I would not consider every part of this answer choice necessary. The selective memory definitely doesn't have to be on the part of medical staff. The legend could have started with other people's selective memory.

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

  3. Trap2% picked this

    the patients in the article were not being serious when they predicted sudden changes in

    Opposite, if anything Out of Scope: not serious The author doesn't give any indication that she's thinking of the patients being facetious. It seems like she thinks in the case of the "full moon babies" and the "clairvoyant patients", every one is acting earnestly and just being fooled by confirmation bias and selective memory.

  4. Too Strong: less likely10% picked this

    babies are less likely to be born during a night with a full moon than during a night

    The author is saying that "babies are not more likely to be born on a full moon", but that doesn't mean the author is saying that "babies are less likely to be born on full moon nights". The author probably thinks that babies are just as likely to be born on any phase of the moon's night.

  5. Opposite, if anything10% picked this

    the idea that medical patients have an instinctual ability to predict sudden changes in their medical status is

    If the "full moon babies" and "clairvoyant patients" were completely analogous cases, then in both cases there would be a popular rumor / a widely held belief that influenced people into having selective memory / confirmation bias.

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