Logical ReasoningDifficulty: Hard

PT123 S3 Q25 Explanation

Some anthropologists argue that the human

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

TopicsFlaw

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Stimulus

Some anthropologists argue that the human species could not have survived prehistoric times if the species had not evolved the ability to cope with diverse natural environments. However, there is considerable evidence that Australopithecus afarensis, a prehistoric species related to early humans, also became extinct. Hence, the anthropologists’ claim is false.

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
25.

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

Answer choices

  1. Correct49% picked this

    confuses a condition’s being required for a given result to occur in one case with the condition’s being sufficient for such a result

    Why this is right

    This identifies the error of reasoning as mistaking a sufficient condition for one that is necessary.

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

  2. Out of Scope7% picked this

    takes for granted that if one species had a characteristic that happened to enable it to survive certain conditions, at least one related extinct

    This relationship has no impact on the argument.

  3. Wrong Flaw14% picked this

    generalizes, from the fact that one species with a certain characteristic survived certain conditions, that all related species with the same characteristic must

    This describes the flaw of generalization. The argument does not generalize from a specific case, but rather uses a specific counterexample

  4. Not a Flaw18% picked this

    fails to consider the possibility that Australopithecus afarensis had one or more characteristics that lessened its chances

    Even if this were true, it would not undermine the argument and so does not point to an error of reasoning in the argument.

  5. Wrong Flaw12% picked this

    fails to consider the possibility that, even if a condition caused a result to occur in one case, it was not necessary to cause

    This describes the flaw of failing to rule out possible alternative causes.

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