Logical ReasoningDifficulty: Easy

PT121 S4 Q10 Explanation

The proposed coal-burning electric

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

TopicsNecessary Assumption

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Stimulus

The proposed coal-burning electric plant should be approved, since no good arguments have been offered against it. After all, all the arguments against by competing electricity producers.

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
10.

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

Answer choices

  1. Out of Scope6% picked this

    The competing electricity producers would stand to lose large amounts of revenue from the building of

    Out of Scope: lose large amounts of $ Our author is certainly suspicious of the validity of arguments coming from competitors, but we don't specifically know why she's suspicious. We can't say she's definitely assuming they would stand to lose large amounts of revenue.

  2. Backwards Logic6% picked this

    If a person’s arguments against a proposal are defective, then that person has a vested interest in seeing that

    We are interested in any answer that says competitor said not good it (vested interest) ? argument But this answer gives us that backwards: Not good argument ? Vested Interest

  3. Out of Scope: who's pleased more2% picked this

    Approval of the coal-burning electric plant would please coal suppliers more than disapproval would please suppliers of fuel

    This is talking about the ramifications of approving the plant. That's beyond the scope of the argument. This author is just trying to get us to "we should approve". She hasn't staked any opinion on what happens after that.

  4. Bad Premise Match6% picked this

    If good arguments are presented for a proposal, then that proposal

    Our author assumes this: no good arguments against ? should be approved This answer says this: good arguments in favor ? should be approved We were never told whether there are / aren't good arguments in favor of the proposal, so that's out of scope.

  5. Correct81% picked this

    Arguments made by those who have a vested interest in the outcome of a proposal

    Why this is right

    This tests the link from Premise to Intermediate Conclusion. arguments made by those with vested ? not good arguments interest in outcome Our author definitely made this move in saying, "No good arguments have been made against; after all, all arguments against have come from a competitor." That clearly reflects an assumption that "if an argument comes from a competitor, it's bad". If we negated this answer, it would turn into an Objection (as correct answers are supposed to): Sometimes arguments made by those with a vested interest are good arguments!

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

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