On some hot days the smog in Hillview reaches unsafe levels, and on so

OFFICIAL EXPLANATION

The premises of the argument contain a Formal Logic setup:

HD = hot days in Hillview
SUL = smog reaches unsafe levels
WBE = wind blows in from the east



The combination of two “some” statements does not yield any inferences. Yet, the author draws a conclusion (SUL <-S-> WBE ) on the basis of the relationship and you must identify the answer that explains why this conclusion is incorrect.

Answer choice (A): There is no proof in the argument that the condition of WBE sometimes accompanies smog reaching unsafe levels—that is the mistake made by the author. The answer would be more attractive if it read as follows:

“mistakes a condition (WBE) that sometimes accompanies hot days in Hillview for a condition that sometimes accompanies unsafe levels of smog”

Answer choice (B): This is the correct answer. When two “some” statements are joined, no inference can be drawn because the group common to both may be large enough that the two sub-elements do not overlap. For example, let’s say there are 10 hot days in Hillview (HD), 1 day when the smog reaches unsafe levels (SUL), and 1 day when the wind blows in the east. Is it necessary that the 1 day when the smog reaches unsafe levels is the same day that the wind blows in from the east? No, but the argument concludes that is the case, and that error is described in this answer choice. For reference purposes, here is the answer choice with each abstract item identified in parentheses after the reference:

“fails to recognize that one set (HD) might have some members in common with each of two others (SUL and WBE) even though those two other sets (SUL and WBE) have no members in common with each other”

Answer choice (C): This answer choice describes the Uncertain Use of a Term, but the argument is consistent in its use of “unsafe.” Therefore, this answer is incorrect.

Answer choice (D): Each premise is plausible regardless of the truth of the conclusion.

Answer choice (E): The argument does not feature causal reasoning. The conclusion clearly states that the two events happen together, but there is no attempt to say that one caused the other. If you chose this answer, try to identify the causal indicators in the argument—there are none.