Logical ReasoningDifficulty: Hard

PT121 S1 Q20 Explanation

Researcher: We have found that

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

TopicsNecessary Assumption

Keep going in LSAT Lab

  • Save & drill this skill build targeted practice sets from questions like this one

  • Video walkthroughs watch every question solved step by step

  • 81 official LSATs as questions, timed sections & full-length tests

Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Stimulus

Researcher: We have found that some cases of high blood pressure can be treated effectively with medicine. Since it is generally accepted that any illness caused by stress is treatable only by the reduction of pressure must not be caused by stress.

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
20.

Which one of the following is an assumption required by the

Answer choices

  1. Out of Scope: the correlation1% picked this

    The correlation between stress and all cases of high blood pressure

    I'll be honest, I've never really seen an answer like this. I don't even know what correlation between stress and all cases of high blood pressure this answer is referring to. There was no such correlation discussed in the argument, so, no, the author wasn't assuming anything about some correlation that was never even discussed.

  2. Opposite of Goal4% picked this

    The reduction of stress in a person’s life can at times lower that

    The author is assuming that "sometimes (in the case of these people treated with meds) one's blood pressure is lowered by means other than the reduction of stress". But this is talking about reduction of stress lowering blood pressure. If we negated this answer, it would say "reducing stress can never lower one's blood pressure", and that would actually strengthen the argument, since the author is assuming that the people whose blood pressure was lowered with medicine did not have it lowered by reducing stress.

  3. Out of Scope5% picked this

    Reduced stress does not reduce a person’s responsiveness to medicine used to treat

    Out of Scope: effects of reducing stress Whenever Necessary Assumption answers use ruling out language like "not / no", it's worth slowing down and negating them to see if they turn into an objection. Would it weaken the argument for us to say, Reduced stress does reduce a person's responsiveness to blood pressure medicine? No that doesn't really have anything to do with this argument. Our only real way to object to this argument is to say, "Hey, author — it's possible that these cases of high blood pressure were caused by stress, and the medicine was effective because it reduced the stress." Negating this answer gives us a scenario where reduced stress came first and then low responsiveness to meds comes second. We want to weaken this author by suggesting a scenario where responsiveness to meds comes first and leads to reduced stress.

  4. Irrelevant Relationship24% picked this

    Some conditions that are treated effectively by medicines are not also treatable through the

    This feels some what close to our assumption: "If treating effectively with meds, then not reducing stress". But this is talking about whether or not a condition is treatable via stress reduction, and in the argument she is assuming that a condition isn't being treated by stress reduction (not that it couldn't be treated by stress reduction). She's never assuming that there are conditions that can't be treated through reduction of stress. She is just assuming that when we treat something with medicine, we are not treating via reducing stress. She's not trying to prove anything about what treatment options are available. She's trying to prove a claim about what causes a condition. To prove that a condition isn't caused by stress, she just needs to show that it can be effectively treated without reducing stress. She doesn't need to to show that it can't be effectively treated by reducing stress.

  5. Correct65% picked this

    Medicine used to treat high blood pressure does not itself

    Why this is right

    When we see the ruling out "not / no" language, we can slow down and negate and see if it turns into an objection. If we say that meds used to treat high blood pressure do reduce stress, then that would badly hurt the argument. The author is trying to prove that these cases of high blood pressure weren't caused by stress. His mechanism for trying to prove that is, "If it was treated by something other than stress reduction, then it wasn't caused by stress". He's assuming that these cases of high blood pressure in the first sentence were not treated by stress reduction (since they were treated by meds). But if the meds reduce stress, then the high blood pressure cases in the first sentence were treated by stress reduction.

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

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free