Logical reasoning PrepTest 110 · Section 2 · Question 25

Incorrect. First, the stimulus discusses the danger of creosote being deposited, which isn't necessarily tied to the amount of creosote produced. It's possible that the cooler smoke results in more deposited creosote even when less is produced. Second, this answer compares the most efficient WBSs to many open fireplaces, which doesn't speak to enough of each to weaken an argument about them overall.

Incorrect. Similar to (A), the amount of creosote produced isn't relevant, it's the amount of creosote deposited. The stimulus also doesn't discuss the relative frequency of use of the two, so we don't know how this answer would play into the comparison.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Wood—burning stoves (WBS) vs. Open fireplaces (OF):
(1) WBSs are more efficient
(2) WBS smoke is cooler than smoke from OFs, depositing more creosote
Creosote — Flammable, can clog a chimney, can ignite inside a chimney
Therefore — WBSs are more dangerous than OF

Answer Anticipation:
The first difficulty in this question is identifying the main point, but there are some structural as well as logical indicators.

Structurally, the argument starts with a less common keyword—"Although." This word generally highlights a fact or view that seems to go against the main point of the argument despite being accepted by the author. It also establishes that the sentence is going to pivot to that main point—so here the conclusion is that wood—burning stoves are more dangerous than open fireplaces. This is backed up by the rest of the argument comparing the two bringing up a danger present in one more than the other (creosote).

With the main point identified it's time to focus on that logic. The argument concludes that WBSs are more dangerous than OFs. Why? Because the former have cooler smoke resulting in more creosote being deposited in the chimney. That creosote is flammable can clog a chimney and can even ignite in the chimney. Those all sound like pretty big dangers!

However the conclusion isn't that WBSs are dangerous it's that they're more dangerous than OFs. While WBSs might have a higher danger from creosote that isn't established as being the only danger that these heat sources present. If OFs are dangerous for other reasons they may be more dangerous than WBSs. Let's find an answer that establishes a way in which OFs are more dangerous than WBSs.

Answer Explanation:
This answer highlights a danger of OFs that is higher than the same danger in WBSs. That calls into question the relative danger posed by the two—if the increased risk of severe accident outweighs the dangers of higher creosote deposits then the argument falls apart. As such it weakens the argument.

Key Takeaway:
Be careful in arguments that reach a relative conclusion that is broader than the premises. Here the premises were about a danger whereas the conclusion was about overall danger. There are multiple factors that go into that determination!

Incorrect. First, the danger is from creosote deposits, which is noted as being related to the temperature of the smoke, not the amount of creosote deposited. Second, a "large amount" can still be less than an even bigger amount and the relative level of danger is what's relevant here.

Incorrect. One can still pose a higher danger than the other even in warm climates, even if the danger isn't particularly high for either. Also, there's no indication that frequency of use is related to danger—maybe a WBS that is used infrequently poses a larger danger because the creosote sits around more. This answer also raises a similarity between WBSs and OFs, which can't weaken an argument with a relative conclusion.