Logical ReasoningDifficulty: Hard

PT102 S4 Q25 Explanation

The dwarf masked owl, a rare

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

TopicsNecessary Assumption

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Stimulus

The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of masked owl will not make its home on the Baja peninsula this winter.

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
25.

The argument depends on assuming which one of

Answer choices

  1. Too Strong1% picked this

    No birds of prey other than the dwarf masked owl nest in

    Too Strong: no other Only Mentioned ≠ Only Thing Just because the dwarf owl is the only bird of prey that nests in spiny cactus who is mentioned in the paragraph doesn't mean the author is assuming that the dwarf owl is the only bird of prey that nests in spiny cactus.

  2. Negation16% picked this

    If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its

    The author is assuming that, If the Baja peninsula → the owl will not make doesn't have spiny cacti its winter home there This answer is just taking that assumption and showing us an illegal negation of it (the left and right sides have been flipped from negative to positive).

  3. Out of Scope3% picked this

    On occasion the dwarf masked owl has been known to make its winter home far from

    Out of Scope: far from normal route This has absolutely nothing to do with the Conclusion, so we should be very dubious. The author says that the owl normally migrates to the Baja peninsula in the winter. That "normally" leaves room for exceptional occasions. But we have no idea (nor do we care) whether those exceptional occasions are ones in which the owl makes its winter home far from the Baja peninsula or near to it.

  4. Reversal21% picked this

    The dwarf masked owl will not make its winter home on the Baja peninsula only if that region

    The author is assuming that, If the Baja peninsula → the owl will not make doesn't have spiny cacti its winter home there This answer is just taking that assumption and showing us an illegal reversal of it. The term "only if" always introduces the Necessary (right side) idea. So the answer is saying: The owl will not make → BP contains no its winter home on BP spiny cacti

  5. Correct60% picked this

    Suitable nesting sites must be present where the dwarf masked owl makes

    Why this is right

    This is saying, if there aren't suitable owl won't make its nesting sites → winter home there That seems to be what the author is thinking. This is providing that link from 3 to 4. Don't try to no no suitable no owl reestablish --> SC ---> nesting ---> on BP this SC population site winter

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

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