Logical ReasoningDifficulty: Hard

PT107 S1 Q15 Explanation

Ordinary mountain sickness, a common

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

TopicsNecessary Assumption

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Stimulus

Ordinary mountain sickness, a common condition among mountain climbers, and one from which most people can recover, is caused by the characteristic shortage of oxygen in the atmosphere at high altitudes. Cerebral edema, a rarer disruption of blood circulation in the brain that quickly becomes life-threatening if not correctly treated from its those of ordinary mountain sickness, cerebral edema is especially dangerous at high altitudes.

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
15.

Which one of the following is an assumption on which the

Answer choices

  1. Correct64% picked this

    The treatment for ordinary mountain sickness differs from the treatment for

    Why this is right

    Was the author thinking that someone with ordinary mountain sickness gets a different medical protocol than does someone with cerebral edema? Yeah, I guess he was! I mean, he's worried about the idea that at high altitudes the medical staff will confuse your cerebral edema for regular ol' mountain sickness and they'll treat the latter rather than the former. If we negate this answer, it becomes a big objection: "Hey, author --- it doesn't actually matter if they confuse our cerebral edema for ordinary mountain sickness. After all, the treatment for ordinary mountain sickness is identical to the treatment for cerebral edema. They're not different. So whether they think we have cerebral edema or ordinary mountain sickness, they'll give us treatment X. Thus, it doesn't make sense to say that cerebral edema is especially dangerous at altitudes where it could be confused with ordinary mountain sickness."

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

  2. Out of Scope: Coma3% picked this

    Cerebral edema can cause those who suffer from it to slip into a coma within

    The author has only committed to the idea that cerebral edema can be "quickly life-threatening, if not correctly treated". She hasn't committed to believing any specific symptoms of cerebral edema (like a coma) once it gets to its dangerous stage.

  3. Too Strong: No Disruption17% picked this

    Unlike cerebral edema, ordinary mountain sickness involves no disruption of blood circulation

    The author doesn't need to assume that cerebral edema and ordinary mountain sickness don't have this symptom in common. She only needs to assume that, "if a doctor thinks you have ordinary mountain sickness, they won't give you the correct treatment for cerebral edema". If we negated this answer and said, "Hey, author -- people with ordinary mountain sickness also get disruption of blood circulation in the brain", it wouldn't hurt the argument. He would say, "Sure, but that ailment can be treated with simple oxygen infusions. Cerebral edema, meanwhile, needs to be treated as soon as possible with a high dose of potassium (for example)."

  4. Out of Scope: Errors of Judgment8% picked this

    Shortage of oxygen at extremely high altitudes is likely to affect thinking processes and cause

    This answer seems to be an Outside Knowledge trap. Being deprived of oxygen does indeed have these effects, in the real world. But that has nothing to do with the logic of this argument. The argument would be the same if shortage of oxygen caused you to suddenly speak with an Irish accent. The author only needs to assume that, "If someone might confuse your cerebral edema with ordinary mountain sickness, then you're less likely to get your cerebral edema correctly treated from its onset". This answer doesn't fall anywhere into that idea.

  5. Out of Scope: Recover Without Treatment8% picked this

    Most people who suffer from ordinary mountain sickness recover without any

    We're told that most people can recover from ordinary mountain sickness, but it doesn't say they recover without any special treatment. Would it hurt the argument if most people did need special treatment to recover from ordinary mountain sickness? No, it would only hurt the argument if the special treatment people needed for ordinary mountain sickness was the same as the special treatment for cerebral edema.

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