#24 - The Kiffer Forest Preserve, in the northernmost part

[Francis O'Rourke]

Choice (E) tells us that there has been zero increase in bears in the Abbimac Valley in the past eight years.

Choice (D) may lead you to conclude that there are fewer bears in the Abbimac Valley, but it does not necessarily tell us this. If the population of bears outside the preserve has descreased by, say, 50 bears and the population in the preserve has increased by only 20 bears, then there would have been 30 fewer bears overall.

However, choice (D) also allows for the possibility of more bears overall. If the decrease outside the preserve was only 10 bears and the increase inside the preserve was 20 bears, we would have 10 more bears compared to eight years ago. This possibility would strengthen the argument. Since both possibilities are present, answer choice (D) does not undermine the argument.

[Iam181]

I still do not understand how answer choice E weakens the aurgument.

It is a straight contradition to the premises in the argument. If the preserve's population which holds most of the bears and is within the valley, doubled, then how can it be that valley's population did not increase.

Thank you so much!

[James Finch]

Hi Iam181,

It looks like you're missing the scope of the argument by a bit: the premises we have are all about the preserve, which is in a part, but not all of the valley as a whole, although it does contain most/a majority of the bears in the valley. But the conclusion is about the future population of the bears in the valley as a whole, not about the population of the bears in the preserve. So while we know that the preserve's bear population has increased, we don't know how the valley's total bear population has or hasn't changed.

(E) undermines the causal argument in the stimulus that the road will cause the overall valley's bear population to increase by showing the same cause in effect (road closure) and no effect (same bear population). So if this is true, what reason would we have to believe that keeping the road closed will suddenly lead to an increase in the valley as a whole's bear population? There wouldn't be one. This makes (E) correct, as it effectively eliminates the premises about the preserve's bear population from supporting the conclusion about the valley's overall bear population.

Hope this clears things up!

[ikim10]

Hello,

For this question I narrowed down my contenders to (D) and (E). While I now see why (D) is wrong, I wanted to discuss my reasons for dismissing (E).

My issue with (E) was temporal. The author's conclusion is about the future - what they think will happen.

While I was attracted to (E) because it discussed the overall valley bear population, because it discussed the past 8 years, I thought it left open the possibility that, while the overall valley bear population hadn't grown yet, it could in the future.

That was my reasoning for dismissing (E). Why is the temporality not a problem, and how do I know when it is an issue?

[Adam Tyson]

It looks to me like you're trying to disprove the conclusion, ikim10, but that's not what the correct answer needs to do. All it needs to do is weaken the argument. That is, it needs to raise some doubt.

Answer E does that by attacking the assumption underlying the argument. The author must believe that the population of bears in the valley has increased over the past 8 years, based solely on the claim that the population in a portion of the valley (the Preserve) increased. If it turns out that the valley's total population hasn't grown at all, as per answer E, then there is no longer any reason to believe that the valley's population will increase in the future. Could it increase? Sure. But does this evidence support that claim, once we take answer E into account? Not at all. E shows that the argument is faulty, regardless of whether the conclusion might just coincidentally turn out to be true at some point in the future.

The temporal issue does matter here, but that's because the author is making an assumption about what happened in the past and predicting that it will continue into the future. Answer E tells us that the assumption about the past is false!