Logical ReasoningDifficulty: Hard

PT149 S4 Q18 ExplanationSanderson intentionally did not tell

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

TopicsNecessary Assumption

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Stimulus

Sanderson intentionally did not tell his cousin about overhearing someone say that the factory would close, knowing that if he withheld this information, his cousin would assume it would remain open. Clearly this was morally wrong. After all, lying is morally wrong. And making a statement with the intention of misleading someone stating and failing to state if they are done with the same intention.

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 required by

Answer choices, explained

  1. Out of Scope5% picked this

    Sanderson believed that his cousin would not want to be informed about

    Out of Scope: "want to be informed" The language of these rules / considerations is really only about truth / falsity, and whether or not we're misleading. The issue of whether or not we're pleasing someone's desire is irrelevant.

  2. Too Strong5% picked this

    No one ever told Sanderson's cousin about the

    Too Strong: "no one told the cousin" It wouldn't hurt the argument to negate this and get, "at least one person told Sanderson's cousin about the factory closing". That wouldn't change anything. I can be rightfully accused of lying to my cousin about X, even if some other person told my cousin the truth about X.

  3. Correct57% picked this

    Sanderson believed that the factory would in fact

    Why this is right

    If we negate this, it is an objection! If Sanderson didn't think the factory was actually closing, then Sanderson would have heard the person who said "it's closing" and thought, "no it isn't". This would mean that allowing his cousin to continue believing that the factory would remain open wasn't an act of deliberate misleading by Sanderson. It would mean that by withholding the story about the guy he overheard, Sanderson was allowing his cousin to continue believe what Sanderson himself believed to be true. In other words, you have to establish that Sanderson believes the factory is closing, in order for it to qualify as deliberately misleading when Sanderson allows his cousin to believe that the factory will remain open.

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

  4. Out of Scope: Predicts a Hypothetical27% picked this

    Sanderson would have lied to his cousin if his cousin had asked him whether the

    Answers that predict what would happen in a hypothetical or counterfactual situation are almost always wrong on Necessary Assumption. Our author might think that Sanderson lied through omission, but our author could still believe that Sanderson wouldn't have lied outright. If we negate this answer and learn that Sanderson might have told the truth if his cousin has asked him point-blank about the factory, that doesn't hurt the author's argument. She could just say, "I'm glad he would be honest if confronted, but that doesn't change the fact that his misleading omission still qualifies as a morally wrong lie."

  5. Out of Scope: something to gain5% picked this

    Sanderson had something to gain by his cousin's continuing to believe that the factory

    So cynical, (E). We don't have to assume anything about what Sanderson's possible motivations could have been, if he in fact was trying to mislead his cousin.

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