Logical ReasoningDifficulty: Medium

PT102 S2 Q15 Explanation

Some plants have extremely sensitive

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

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Stimulus

Some plants have extremely sensitive biological thermometers. For example, the leaves of rhododendrons curl when the temperature of the air around them is below 0°C (Celsius). Similarly, mature crocus blossoms open in temperatures above 2°C. So someone who simultaneously observed rhododendrons with uncurled leaves, crocuses with mature but unopened blossoms, thermometer’s reading was accurate to within plus or minus 1°C.

What this question is testing

Weaken

Your task

Find the choice that makes the argument's conclusion less likely to be true.

Common trap

Answers that look negative but attack a claim the argument never relied on.

Winning move

Find the assumption the argument depends on, then pick the choice that undermines it.

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, if true, most seriously undermines the

Answer choices

  1. Out of Scope: rhododendron blossoms11% picked this

    Neither rhododendrons nor crocuses bloom for more than a few weeks each year, and the blossoms of rhododendrons growing in any area do not

    This answer seems to be trying to weaken by convincing us that someone would never simultaneously observe uncurled rhododendron leaves at the same time as unopened crocus blossoms. But ... 1) this conclusion is really hypothetical not literal. The author isn't saying someone will find themselves in this position. It's sort of implied that we're saying, "If you happened to see A and B with a thermometer that read 1° ..." 2) this isn't talking about uncurled rhododendron leaves. It's talking about the blossoms of rhododendrons, which wasn't a part of this argument. We have no idea what the temperature constraints are on the blossoms of a rhododendron.

  2. Out of Scope: people's enjoyment0% picked this

    Many people find it unpleasant to be outdoors for long periods when the temperature is

    This argument has nothing to do with whether a hypothetical person holding this 1° thermometer finds the outdoors pleasant or unpleasant. The author wasn't suggesting that we should all go do this experiment in 1° weather.

  3. No Impact2% picked this

    The climate and soil conditions that favor the growth of rhododendrons are also favorable to

    If anything this feels like it strengthens the possibility that rhododendrons and crocuses could grow in the same place, but we don't actually care if they ever do. The author is speaking to a very hypothetical thought experiment where you happen to see a certain rhododendron stage and a certain crocus stage. He isn't promising that anyone will ever actually see this in real life.

  4. Correct76% picked this

    Air temperature surrounding rhododendrons, which can grow 12 feet tall, is likely to differ from air temperature surrounding crocuses, which are normally only a

    Why this is right

    This allows us a way to argue that the conclusion could be wrong! Let's say temperature at ground level is actually 1.9°. Since the temp is more than 2 greater up 12 feet, that means the air temperature 12 feet up is over 3.9° C. The temperature 6 feet up, where our six foot scientist is holding her thermometer is 2.9° C. This would allow crocuses to be unopened (because it's less than 2° at ground level). And this would allow rhododendron leaves to be uncurled (since it's more than 0° twelve feet up where they live). But if the thermometer says 1° even though it's really 2.9°, then we've shown how the thermometer could be off by more than 1° C, even though we're seeing unopened crocus blossoms and uncurled rhododendron leaves. Is this answer insane? 100% certified crazy. They're talking about a temperature change of more than 2° C (which is like 5° F) between ground level and 12 feet up? I mean, yes, if you have a room with pitched ceilings and you climb up a 12 foot ladder, you will feel that it is at least 5° F warmer at the top of the ladder. But outdoors it's a little insane to think that air temperatures would vary that much. But that's not our job. The question system isn't saying, "Do you think this answer is true?" It's asking, "If you pretend this answer is true, would it allow you to weaken the argument?" And this is the only answer helping us to show how you could see uncurled leaves, unopened blossoms, and 1° on the thermometer, even though it's either under 0° or above 2° in reality.

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

  5. Unclear Impact11% picked this

    Certain types of thermometers that are commonly used to measure outdoor temperatures can be extremely accurate in moderate temperature ranges but much less accurate

    Is the hypothetical thermometer in our thought experiment one of these "certain types of thermometers"? We don't know, so this answer doesn't have any clear relevance.

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