Logical ReasoningDifficulty: Easy

PT117 S2 Q18 Explanation

Bram Stoker’s 1897 novel Dracula

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

TopicsNecessary Assumption

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Stimulus

Bram Stoker’s 1897 novel Dracula portrayed vampires—the “undead” who roam at night to suck the blood of living people—as able to turn into bats. As a result of the pervasive influence of this novel, many people now assume that a vampire’s being able to turn into a bat is an essential for vampire myths existed in Europe long before Stoker’s book.

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

Answer choices

  1. Out of Scope: nocturnal2% picked this

    At least one of the European vampire myths that predated Stoker’s book did not portray

    The author's argument doesn't care whether vampires are always portrayed as strictly nocturnal or not. He cares about whether vampires are always portrayed as being able to turn into a bat.

  2. Out of Scope: Central / South America1% picked this

    Vampire myths in Central and South America, where real vampire bats are found, portray vampires as able

    The author doesn't need to assume anything about Central and South America. If we negated this answer and said, "The vampire myths in Central and South America do not portray vampires as able to turn into bats", that would actually prove his conclusion true! The correct answer, when negated, would weaken the argument.

  3. Too Strong: only in Europe8% picked this

    Vampire myths did not exist outside Europe before the publication of

    The author doesn't need to assume the strong idea that vampire myths only existed in Europe prior to Stoker's book. If we negate this and say that vampire myths also existed outside Europe prior to Stoker's book, that wouldn't affect the argument at all. The author is only trying to prove that there is at least one vampire myth, from anywhere, in which the vampire is not able to turn into a bat.

  4. Correct81% picked this

    At least one of the European vampire myths that predated Stoker’s book did not portray vampires as able

    Why this is right

    The author is trying to prove that "being able to turn into a bat" is not an essential part of vampire myths, so he needs to support that by showing us that there is at least one vampire myth in which the vampire is not able to turn into a bat. His only premise (signified by "for") is that vampire myths existed in Europe prior to Stoker's book. He must, therefore, be assuming that in at least one of these vampire myths, the vampire was not able to turn into a bat. If we negated this, the "at least one" would become "none", and we would have a double-negative: none of the pre-Stoker vampire myths did not portray vampires as being able to turn into bats. If I say "none of my friends did not have ice cream", I'm saying "all of my friends had some ice cream". Here, we'd be getting "all of the pre-Stoker vampire myths did portray vampires as being able to turn into bats". That would definitely weaken the author, since he would then have no relevant premise at all with which to support his conclusion.

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

  5. Out of Scope: Stoker's familiarity7% picked this

    At the time he wrote Dracula, Stoker was familiar with earlier

    The argument doesn't care whether Stoker knew of any other vampire myths, or whether he just created his vampire myth purely from his own imagination (not knowing that other vampire myths even existed). Neither one has any impact on our conversation, which is about whether there's ever been a vampire myth in which the vampire was not able to turn into a bat.

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