Bunuel wrote:
Global surveys estimate the earth’s population of nesting female leatherback turtles has fallen by more than two-thirds in the past 15 years. Any species whose population declines by more than two-thirds in 15 years is in grave danger of extinction, so the leatherback turtle is clearly in danger of extinction.
Which one of the following is an assumption that the argument requires?
(A) The decline in the population of nesting female leatherback turtles is proportional to the decline in the leatherback turtle population as a whole.
(B) If the global population of leatherback turtles falls by more than two-thirds over the next 15 years, the species will eventually become extinct.
(C) The global population of leatherback turtles consists in roughly equal numbers of females and males.
(D) Very few leatherback turtles exist in captivity.
(E) The only way to ensure the continued survival of leatherback turtles in the wild is to breed them in captivity.
Project CR Butler: Critical Reasoning
For all CR butler Questions Click HereEXPLANATION FROM Fox LSAT
Silly little trick here. The first premise is about
nesting female leatherback turtles, but the second premise, and the conclusion, are about leatherback turtles
overall. So the argument has assumed that the observed decline in nesting female leatherback turtles is also true in leatherback turtles overall. If that’s not true, then the argument just doesn’t make sense.
Put another way, what if it’s possible to lose two-thirds of the females, but not have a decline in the total population? That is somewhat hard to believe, but if it’s true then the argument fails.
A) This feels like a trap to me because the word “proportional” is too strong. This would certainly strengthen the argument, but it feels like a sufficient assumption rather than a necessary assumption. If this answer is true, it would
prove the argument’s conclusion. That’s a sufficient assumption. If this answer is false, it becomes, “The decline in the population of nesting female leatherback turtles is not proportional to the decline in the leatherback turtle population as a whole.” But so what? That doesn’t ruin the argument. The decline doesn’t have to be “proportional” in order to still be devastating to the population. For example, what if the female population declined by 70%, and the total population declined by 95%? That’s not “proportional,” but it would strengthen the argument rather than weaken it. On a Necessary Assumption question, we need to pick an answer that,
if untrue, would cause the argument to fail. This isn’t it.
B) No, this answer goes further than the argument actually went. The argument only concludes that the leatherback is “in danger of extinction.” That doesn’t mean that the leatherback will surely go extinct.
C) Again, like A, this is too specific. Males and females don’t have to be roughly equal in numbers for the argument to make sense. What if there are far more females than males? If there are far more females than males, and females have declined drastically, then surely the overall population has also declined drastically.
D) Huh? Totally irrelevant.
E) No, not even close. Like D, captivity can’t possibly be relevant.
Yikes. We’ve eliminated all five answers, and I really hate all five. As it turns out the answer is A, but I think this is a truly terrible question. There is no way that A is “required” by the argument. Answer choice A would be decent if this were a Sufficient Assumption question, but the question asked us for a necessary assumption. Chalk this one up to an error on the test makers’ part.
The answer is A.
close
12 Nov 2021, 02:30
25%
(medium)
22%
(01:26)
wrong 
