Logical ReasoningDifficulty: Hard

PT121 S4 Q25 Explanation

Therapist: In a recent study,

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

TopicsFlaw

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Stimulus

Therapist: In a recent study, researchers measured how quickly 60 different psychological problems waned as a large, diverse sample of people underwent weekly behavioral therapy sessions. About 75 percent of the 60 problems consistently cleared up within 50 weeks of therapy sessions are all that most people need.

What this question is testing

Flaw

Your task

Describe the reasoning error the argument actually commits.

Common trap

Answers that name a real logical flaw the argument doesn't actually make.

Winning move

Articulate the gap in the reasoning yourself, then match it to the choice that describes that 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
25.

The therapist’s argument is logically most vulnerable to criticism on the grounds

Answer choices

  1. Too Strong: no22% picked this

    takes for granted that there are no psychological problems that usually take significantly longer to clear up than

    Since this begins with takes for granted, we can ask ourselves whether the argument needed to assume this claim. The author needs to assume that "there are no problems that usually take longer to clear up than the 60 studied and which afflict most people". But without that tag, it's too strong. If we negate this assumption and say, "Hey, author -- there is at least one psychological problem that takes longer than any of the problems in the study", it wouldn't weaken the argument. The author can say, "Cool, yeah, I realize that. I didn't say 50 weeks would be enough for everyone just for most people. I admit, 50 weeks won't be enough for people who have that problem, but that's not most people." Until we say that most people have a sort of problem that takes longer than the 60 studied, it doesn't become much of an objection.

  2. Correct45% picked this

    fails to address the possibility that any given one of the 60 psychological problems studied

    Why this is right

    Since this starts with fails to consider, we'll ask ourselves if the idea that follows would be an Objection. Can we hurt the argument by saying that "any one of the 60 studied problems could afflict most people"? Could that give us a way to argue that, "50 weeks would not be enough for most people"? Yes! 75% is 3/4, so of the 60 problems studied, 45 of them were cleared up. But what if most people are afflicted with one of the 15 problems that didn't clear up? What if the ones that didn't clear up in 50 weeks are some of the most common ones, like depression and anxiety? The author was assuming that because most problems cleared up, that would take care of most people. But if the problems that didn't clear up in the 50 weeks are the most common psychological problems, then we have a way to say that "most people would need more than 50 weeks".

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

  3. Too Strong: no one14% picked this

    takes for granted that no one suffers from more than one of the 60

    Since this begins with takes for granted, we can ask ourselves whether the argument needed to assume this claim. If we negate this assumption and say, "Hey, author — there is at least one person who suffers from more than one of these problems", it wouldn't weaken the argument. The author can say, "Cool, yeah, I that's fine. I didn't say 50 weeks would be enough for everyone just for most people. I admit, 50 weeks won't be enough for people who have a multitude of problems, but that's not most people." Until we say that most people have more than one problem, it doesn't become much of an objection.

  4. Not an Objection3% picked this

    fails to address the possibility that some forms of therapy have never been proven to be effective as

    Since this starts with fails to consider, we'll ask ourselves if the idea that follows would be an Objection. Can we hurt the argument by saying that "there are some forms of therapy that have never been proven effective for psychological problems?" Of course not. They are totally irrelevant to the author's argument, which is specifically about behavioral sessions, which have been plausibly shown to be effective against 75% of the psychological problems in this study.

  5. Not Necessary16% picked this

    takes for granted that the sample of people studied did not have significantly more psychological problems, on average, than

    Since this begins with takes for granted, we can ask ourselves whether the argument needed to assume this claim. If we negate this assumption and say, "Hey, author -- the people studied did have way more psychological problems, on average, then the general population", would that weaken? No, not quite. It actually strengthens. The author could say, "I know, right? The people in this study were way more addled by problems than are most people, and even for them 50 weeks was all that was needed! So you know that 50 weeks would be enough for most people." The author needs to assume an inverse of this: "the sample of people studied did not have significantly fewer problems, on average, than the overall population". If you negate that assumption, you get an objection. We might be thinking, "Yes, but isn't the author just in general assuming that this sample is representative?" No, not necessarily. If the sample is representative that strengthens the argument, but it's not necessary, as the negation test just revealed. If a drug were shown to be effective on the worst headaches, then you would assume that it will help most people with headaches. Proving yourself against tougher competition shows you're ready for ordinary competition.

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