Bunuel wrote:
Sickles found at one archaeological site had scratched blades, but those found at a second site did not. Since sickle blades always become scratched whenever they are used to harvest grain, this evidence shows that the sickles found at the first site were used to harvest grain, but the sickles found at the second site were not.
Which one of the following, if shown to be a realistic possibility, would undermine the argument?
(A) Some sickles that have not yet been found at the first site do not have scratched blades.
(B) The scratches on the blades of the sickles found at the first site resulted from something other than harvesting grain.
(C) Sickles at both sites had ritual uses whether or not those sickles were used to harvest grain.
(D) At the second site tools other than sickles were used to harvest grain.
(E) The sickles found at the first site were made by the same people who made the sickles found at the second site.
EXPLANATION FROM Fox LSAT
Classic pattern of flawed reasoning here. Basically, the flaw here is, “Getting eaten by a shark causes death, therefore anybody who is dead must have been eaten by a shark.” Note that only one part of the argument’s conclusion is flawed. If sickles always get scratched when used to harvest grain, then the sickles at the second site, which were unscratched, were definitely
not used to harvest grain. (If you’re not dead, then you were definitely
not eaten by a shark.) But the first part of the conclusion (the scratched sickles
were used to harvest grain) is fundamentally flawed because there might be a lot of other ways that sickles can get scratched. For example, when smiting your enemies by chopping off their heads or otherwise dismembering them, you might scratch your sickle.
Having identified the argument’s major weakness, it shouldn’t be heavy sledding to find an answer that would “undermine” (i.e. weaken) the argument. Basically, anything like, “There are a lot of other ways to scratch a sickle besides harvesting grain with it,” would be a terrific answer. If the answer involves any smiting, that will just be a bonus.
A) Huh? This is a truly bizarre answer. If the sickles “have not yet been found” then how the hell would we know they don’t have scratched blades? Really weird —this answer can’t even logically support its own weight. And even if it did, it wouldn’t point out that there are other ways to scratch a sickle, which is what we’re looking for here.
B) Boom. This is exactly what we are looking for. If this is true, then the argument’s conclusion that “the sickles found at the first site were used to harvest grain” is destroyed. This is almost guaranteed to be our answer.
C) Who gives a **** whether or not the sickles had ritual uses? A sickle could have ritual uses and still be used, or not used, to harvest grain. This answer is simply irrelevant. It’s like saying, “The sickles were stored in the barn when not in use.” Who cares?
D) Also irrelevant. We don’t care if they found a John Deere harvester that had traveled backward in time to harvest the grain at the second site—they still might have, or might not have, also used sickles to harvest grain at that site. This answer doesn’t change the logic of the argument at all.
E) The identity of the sickle creator is simply not at issue here. If you chose this answer, you aren’t paying close enough attention to 1) the argument or 2) what you’ve been asked to do. The conclusion is, “Sickles at the first site were used to harvest grain, and sickles at the second site were not.” We needed to attack that conclusion, and only B does that.
So our answer is B.
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