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This argument presents the conclusion in the middle sentence:
  • "there is little justification for health warnings that urge the removal of any bats residing in buildings where people work or live."

The premises supporting this conclusion appear in the first and last sentences:
  • "Almost all cases of rabies in humans come from being bitten by a rabid animal, and bats do carry rabies."

    "Bats are shy animals that rarely bite, and the overwhelming majority of bats do not have rabies."
The reasoning here relies on bats being shy and not having rabies, and on that basis indicates that we need not worry about removing them from buildings where people work and live.

Answer choice (B) weakens the argument by showing that bats in people-inhabited buildings present a certain type of problem. Namely, when any animal (including bats) become rabid, they not only stay near where they are (which would be buildings) but become far more aggressive. If this is the case, the wisest course of action would be to remove now what could be a future source of serious problems. that idea weakens the argument, and thus (B) is correct.
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Hi! I would appreciate some help with this question and a good prephrase. Would a good one maybe be "something that says we should be concerned about bats even though they rarely bite and most of them do not have rabies?" From there, how would you attack these answers and react? thanks!
 James Finch
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Hi Lsat180Please,

Weaken questions like this can be tough to come up with a very precise prephrase. Instead, the best way to prephrase a stimulus like this is to understand how it works mechanically, and tailor a prephrase as specifically as possible to attack the conclusion.

Here, we have a conclusion that is then supported by two premises, neither of which are specific to the case the conclusion addresses (potentially rabid bats in human-occupied buildings). With that in mind, my first thought would be to make one or both of those premises inapplicable to the specific case in the stimulus, and test the answer choices to see if any do that. Sometimes there is a fairly obvious way to do that that you can add to your prephrase, but I can't think of one in this case. Instead, I'll test the answer choices based on the more general criteria.

(A)--Seems to support the conclusion, if anything. Loser.

(B)--This one takes a moment to think through, but once you do, the implications are clear: "less mobile" seems to fit the scope of being in buildings, and "more aggressive" is a direct attack on the premise that bats are shy and rarely bite. Contender.

(C)--Seems promising at first (attacking the same premise as (B)) until I thought it through: this would actually help widen the scope of the conclusion from just bats to "most rabid animals," while we're trying to make it reasonable to get rid of them. Contender on first pass, but ultimately a Loser.

(D)--Clearly strengthens the conclusion. Loser.

(E)--Irrevelant. Loser.

So (B) and (C) are the only attractive answer choices here, and it does take a moment to realize the difference between what they both do, as both are aimed at the same premise. But always take the time on these questions, especially at this point in the test, to think through logical implications and make sure that what an answer choice seems to do is what it actually does.

Hope this helps!
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I feel like B is a weak weakener, if that makes sense. It doesn't destroy the argument, but it serves its purpose, I guess. My thought process during BR was that by showing that rabid bats are outside of the generalization of all bats made by Pratt at the end, whereas "B" shows how rabid bats could potentially be amongst the "any" left in proximity to people in buildings, and of course more dangerous. I also don't know what purpose "less mobile" was serving in this a/c. Was it to up the rigor of the question. Would I be going too far to say that there's some relationship between the bats being shy and "less mobile"?
 Jeremy Press
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Hi lsbound22,

This is such an interesting question, and I was just talking through this one with a student of mine yesterday!

I agree wholeheartedly with your assessment that answer choice B does not fully invalidate the conclusion of the argument. But, as you correctly note, that's not necessary on a weaken question, where the task is simply to cast some doubt on the conclusion. Answer choice B does cast that doubt (it's something that makes the premises slightly less likely to lead necessarily to the conclusion--for the reasons that James identifies in the post above yours), thus it's enough to select it.

The reference to rabid bats being "less mobile" is, as James notes, intended to provide some loose additional support to the idea that they might be found in buildings (after all, being in a building would by itself make them "less mobile," since there's less space for them to move in). Does that reference automatically mean they'll be in buildings? No, but it makes it slightly more likely that they will be found there. That's all we need for the weakening effect we're looking for. To address your last question, if that's how we read that reference, then I don't think it's necessary to see any correspondence between shyness and lessened mobility.

I hope this helps!


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