Logical ReasoningDifficulty: Hard

PT110 S2 Q25 Explanation

Although wood-burning stoves are

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

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Stimulus

Although wood-burning stoves are more efficient than open fireplaces, they are also more dangerous. The smoke that wood-burning stoves release up the chimney is cooler than the smoke from an open flame. Thus it travels more slowly and deposits clog a chimney—or worse ignite inside it.

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
25.

Which one of the following, if true, most seriously weakens

Answer choices

  1. Weak Impact18% picked this

    The most efficient wood-burning stoves produce less creosote than do many

    The premise was generalizing about wood burning stoves, so we would interpret it to mean, "On average, wood-burning stoves deposit more creosote than open fireplaces do". This answer chops away at that somewhat, saying that "if you happen to have the most-efficient wood burning stove, then it produces less creosote than do at least a handful of open fireplaces". But this doesn't change the underlying the generalization. We can say that "Adults are taller than children" as a generalization, and saying "the shortest adults are not as tall as are many children" is still compatible with that generalization.

  2. Unclear Impact11% picked this

    The amount of creosote produced depends not only on the type of flame but on how often the

    This is too wishy-washy to have any clear impact. Okay, the amount of creosote depends on the type of flame and how often the stove or fireplace is used. Well ... is a wood-burning stove generally used more/less often than an open fireplace? We don't know, so this answer doesn't score a point for wood-burning or open fireplace.

  3. Correct61% picked this

    Open fireplaces pose more risk of severe accidents inside the home than

    Why this is right

    This scores a big point in favor of "open fireplaces are more dangerous". Apparently they pose more risk of severe accidents inside the house. This alone, of course, does not prove that open fireplaces overall are more dangerous, but it certainly nudges us in that direction. Right now we're thinking that with wood stoves, there's a bigger risk of creosote clogging or igniting in a chimney. With open fireplaces, there's a bigger risk of severe accidents inside the home. It would be hard to conclude at this point that wood-burning stoves are more dangerous.

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

  4. Relative vs. Absolute10% picked this

    Open fireplaces also produce a large amount of

    The argument is about which stove is more dangerous. With this answer we now know that both types of stove produce a lot of creosote. But wood stoves produce more creosote, so we know when it comes to creosote that wood stoves are more dangerous.

  5. No Impact1% picked this

    Homeowners in warm climates rarely use fireplaces or

    This answer tells us about people who don't use either type of heat source. That has no effect on our scorecard of which heat source is more dangerous.

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