Critical Reasoning

In the past year, there has been a dramatic increase in the number of people killed by alligators in Florida. During this same time, there has been an increase in the development of new houses, golf courses, and shopping areas in former wilderness areas within the state. Therefore, the increase in fatal alligator attacks must have been caused by the increase in the number of humans living in the alligator's habitat.

Which of the following, if true, most seriously calls into question the explanation above?

a) Two years ago, a government initiative to reduce the alligator population size by destroying alligator eggs ended.

b) An increase in fatal alligator attacks tends to make people more cautious around lakes, ponds, swamps and canals.

c) The number of people killed by snake bites, spider bites and scorpion stings in Florida has held steady for many years.

d) Many of the new state residents have moved to newly constructed areas near water that is suitable for habitation by alligators.

e) The undeveloped areas of Florida have decreased in area by 5% in the past year.

This is a weaken critical reasoning question. That means that our approach is to first find the conclusion of the argument and then premises, identify the logical gap, and then PREDICT an answer. Strengthen/weaken critical reasoning answer choices are very tricky, but you can avoid falling for a lot of traps if you make a prediction upfront. You do not need to be extremely specific, but you should try to have a general idea of what you think the flaw is (or potentially several flaws). So for this argument, we have:

P) Increase in people killed by alligators in Florida during past year
P) Increase in development in former wilderness areas in past year
GAP
C) The increase in deaths must be caused by the increase of humans living in the alligators' habitat.

This is an error of causation, a common error type on the gmat. When a question says that "x causes y," other possible solutions are that "y causes x," "z causes x," or they are just correlated. Here the most likely flaw seemed to me to be that z causes x, meaning another cause is actually responsible for the increase in deaths. Another potential flaw that I saw is the idea that the second premises mentions development occurring in these lands, but it does not actually indicate that people are living there yet, which the conclusion then assumes. This doesn't end up being our answer choice, but it is a good thing to recognize.

Answer choice A addresses the "z causes y" error nicely. If there are now more alligators than before, because the government stopped destroying eggs two years ago, then it may actually be the fact that there are more alligators in florida now (z) causing the increase in deaths (x), not the increased development (y) causing the deaths.

I hope this helps!

is the correct Answer - A ?

Answer choice A addresses the "z causes y" error nicely. If there are now more alligators than before, because the government stopped destroying eggs two years ago, then it may actually be the fact that there are more alligators in florida now (z) causing the increase in deaths (x), not the increased development (y) causing the deaths.

I considered this choice and then rejected it assuming that since they were eggs, adult alligator population could not affect in two years! Am I overthinking? and then I zeroed to d!

Can anyone suggest correct answer.

Hi Brandon,

Thanks for the excellent explanation. I liked the way you made it crystal clear. If I am not wrong, choice D actually does the assumption that people started living in those newly constructed places. So, D strengthens author's conclusion.
Does that make sense?


~Binit.

D seems correct answer to me also.

nikhilgmat31 wrote:is the correct Answer - A ?

I'm sorry if I did not make myself clear. Yes the answer is A.

bubbliiiiiiii wrote:

Answer choice A addresses the "z causes y" error nicely. If there are now more alligators than before, because the government stopped destroying eggs two years ago, then it may actually be the fact that there are more alligators in florida now (z) causing the increase in deaths (x), not the increased development (y) causing the deaths.

I considered this choice and then rejected it assuming that since they were eggs, adult alligator population could not affect in two years! Am I overthinking? and then I zeroed to d!

I entirely understand that logic, and honestly the question is poorly worded. In terms of overthinking, that thought occurred to me also but you do not want to bring in outside information, so thinking about the difference between baby/adult alligators is probably not great. But on the flip side, thinking that eggs turn into alligators is itself basic outside information. So in terms of what you faced here, you would have to pick A simply because all of the other answer choices are very bad. You would almost pick it by default even though you do not like that aspect of it.

B - pretty irrelevant, and if anything strengthens the conclusion. If people are more cautious in these areas but fatalities are still increasing, there must be another reason that the fatalities are increasing
C - These are different kinds of bites/stings that are less likely to be fatal. It is entirely possible that these bites/stings increased along with alligator attacks, but that alligator attacks typically end up fatal where as these attacks do not
D - This fills in another weakness in the argument that I had mentioned in my initial analysis, the assumption that people are moving to these newly developed areas. This fills that gap in and therefore strengthens the argument (the opposite of what we want)
E - This is basically just piggybacking off of a premise that we already know - wilderness is being developed. Thus it is irrelevant.

So even with your minor dislike of A, you would have no choice but to pick it given these alternatives.

I hope this helps!

binit wrote:Hi Brandon,

Thanks for the excellent explanation. I liked the way you made it crystal clear. If I am not wrong, choice D actually does the assumption that people started living in those newly constructed places. So, D strengthens author's conclusion.
Does that make sense?


~Binit.

That is exactly correct Binit. D strengthens the argument, and therefore does the opposite of what we want and is wrong. There will almost always be 1 or 2 trap answers to strengthen/weaken questions that do the opposite of what you want -> a trap answer to a strengthen question will weaken the argument, and a trap answer to a weaken question will strengthen it. Here we have a weaken question, and D is a trap answer that instead strengthens.