Logical ReasoningDifficulty: Hard

PT18 S4 Q18 Explanation

Professor Hartley’s new book on moral philosophy

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

TopicsNecessary Assumption

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Stimulus

Professor Hartley’s new book on moral philosophy contains numerous passages that can be found verbatim in an earlier published work by Hartley’s colleague, Professor Lawrence. Therefore, in view of the fact that these passages were unattributed in Hartley’s acknowledging the intellectual debt owed to Lawrence.

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.

Which one of the following is an assumption on which the argument

Answer choices

  1. Too Strong: could not have without8% picked this

    Hartley could not have written the new book without the passages

    The author doesn't need to assume that these passages were absolutely necessary to the book. Even if they weren't, the author would still be able to make the same case that H may have stolen the passages without fair attribution.

  2. Not Necessary20% picked this

    While writing the new book, Hartley had access to the manuscript

    This would Strengthen but it isn't necessary. In order for H to have "stolen" the material from L, does she need to have obtained it via a manuscript? No, of course not. Maybe L emailed H these passages at some point to get H's feedback. Maybe L often quotes these passages aloud in the university teacher's lounge. Maybe H just got these passages from the final published version of L's book (not the manuscript).

  3. Out of Scope: should6% picked this

    A book on moral philosophy should contain only material representing the

    Nothing in this argument is normative, so we can't say the author is assuming anything about what "should" be the case. Whether a moral philosophy book should / shouldn't include anything besides the author's thoughts doesn't affect whether or not this book did / didn't steal L's material without proper attribution.

  4. Correct66% picked this

    Lawrence did not get the ideas in the passages in question or did not get their

    Why this is right

    This rules out an alternate explanation. If we negate it, this answer badly weakens the argument (which tells us that this answer is something that needs to be assumed). NEGATION: Lawrence got the ideas in the passages originally from Hartley. This would badly weaken the author's story that Hartley stole the ideas from Lawrence.

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

  5. Too Strong: best possible1% picked this

    Hartley considered the passages in question to be the best possible expressions of the

    It doesn't matter whether H considered these passages to be the "best" possible expression, the 2nd best, the 3rd best. She obviously considered them "good enough" to put in her book, but the author's argument isn't affected in any way if Hartley thought these expressions were "good enough, even if not the best possible".

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