Logical ReasoningDifficulty: Hard

PT107 S1 Q18 Explanation

Some planning committee members

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

TopicsMust be True

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Stimulus

Some planning committee members—those representing the construction industry—have significant financial interests in the committee’s decisions. No one who is on the planning committee lives many of them work there.

What this question is testing

Must be True

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

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.

If the statements above are true, which one of the following must

Answer choices

  1. Too Strong2% picked this

    No persons with significant financial interests in the planning committee’s decisions are not in

    Too Strong: no one w/ financial interest This paragraph tells us about some people who have significant financial interests in the committee's decisions, but it doesn't tell us anything about everyone who has significant financial interests. This answer is trying to derive a conditional significant financial → in construction interests in PC's decisions industry We can't derive this strong conditional relationship. It would be like if I told you, "Some people on that basketball team wear watches", and then you acted like we know "No who wears a watch doesn't play basketball".

  2. Too Strong17% picked this

    No person who has significant financial interest in the planning committee’s decisions lives

    Too Strong: no one w/ financial interest This paragraph tells us about some people who have significant financial interests in the committee's decisions, but it doesn't tell us anything about everyone who has significant financial interests. This answer is trying to derive a conditional significant financial → don't live in interests in PC's decisions suburbs Since we don't know anything about "all people who have significant financial interests", it would be impossible for us to know whether they all live outside the suburbs or whether some of them live there. We know some of them don't live there, but this answer is saying all of them don't live there.

  3. Unknown Relationship16% picked this

    Some persons with significant financial interests in the planning committee’s decisions work

    This is lovably weak, thus very provable. But what do we know about people who work in the suburbs? We know many planning committee people work in the suburbs. Okay, do we know that those many planning committee people have significant financial interests in the PC's decisions? Nope. The first sentence tells us that some planning committee members have significant financial interests, but we have no way to prove that the "many members who work in the suburbs" must overlap with the "some members who have significant financial interests". Stephen Colbert, the TV host, is the youngest of like 14 siblings. We could say "Some Colbert children are rich TV hosts. Many Colbert children have unrecognizable faces." Does that allow us to prove that "Some rich TV hosts have unrecognizable faces"? Of course not. The SOME group and the MANY group don't have any forced overlap.

  4. Out of Scope11% picked this

    Some planning committee members who represent the construction industry do not work

    Out of Scope: Don't Work in Suburbs This one is also lovably weak, but it's not as tempting since we have literally zero information about people who don't work in the suburbs. The paragraph has only told us about people who do work in the suburbs.

  5. Correct54% picked this

    Some persons with significant financial interests in the planning committee’s decisions do not live

    Why this is right

    We know Some ppl w/ significant are PC members financial interests And we know All PC members do not live in suburbs So chaining that together, we can derive Some ppl w/ significant do not live in suburbs financial interests FORMAL NOTATION Some SFI are on PC + on PC → ~live in suburbs --------------------------------------- Some SFI ~live in suburbs EVEN MORE NERDY SFI <--s--> PC PC → ~Live in Burbs SFI <----s-------> ~Live in Burbs

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

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