Hi Vlad,
The stimulus in this question gives us a straightforward conditional relationship:
"If ecology and the physical sciences were evaluated by the same criteria, ecology would fail to be a successful science"
with a an explanatory statement immediately afterwards. So I diagrammed this conditional as:
SC (same criteria)
ES (
ecology successful)
as well as the contrapositive:
ES
SC
The stimulus goes on to give us that ecology is successful as a science, and thus is not being judged by the same criteria as the physical sciences. This conclusion is a restatement of the contrapositive of the conditional relationship we were first given, and have already diagrammed, and is logically valid.
This is a Parallel Reasoning question, so we're looking for an answer choice that parallels the structure in the stimulus. In this case, this means giving us a conditional statement, followed by stating its contrapositive to be factually correct. So now let's look at the answer choices:
(A) gives us a conditional statement that has two potential necessary conditions, at least one of which must happen, diagrammed as:
STI
PWI or WID
And then tells us that one of the necessary conditions (PWI) will not occur, concluding that the other must occur. Clearly this is different from our stimulus, and thus an incorrect answer choice.
(B) has a statement that gives us another straightforward if/then conditional with a single sufficient and a single necessary condition, but then concludes with a new element, demand, not present in the conditional. Again, clearly different from the reasoning in the stimulus.
(C) has a conditional statement (L&SM
DLF), then tells us that the sufficient condition will be true in the future, before concluding that the necessary condition will thus be true in the future as well. While this answer choice is closer, it still does not parallel the stimulus because it is the conditional statement, not its contrapositive, that is presented as true.
(D) gives a conditional statement (PARSS
[Probably] ASAR) then states that the sufficient condition is rarely true, before concluding that the necessary condition is categorically not true. Besides the (again) lack of the contrapositive, this answer choice introduces problems with the scope of its claims ("probably", "rarely") that make it clearly different from the stimulus, and therefore incorrect.
(E) starts off with a conditional statement (ADP
PAEF), then tells us the necessary condition is not true, before concluding that the sufficient is not true, ie it concludes the contrapositive (
PAEF ADP) of the original conditional statement, paralleling the stimulus exactly. This makes (E) the correct answer choice.
Hope this helps!
