• Nathan Fox

Pertinent Evidence

Test 58 - Section 4 - Question 23

Logical Reasoning

Difficulty: 5


Explanation


Demon user Will C proclaims,


"I chose A over E because I overlooked the word 'Meteor' in answer B. Damnit. So—B is correct as it eliminates meteors as possibility? But to be sure, it seems that A and E both strengthen, just not as well as B... Well played, LSAC Dicks."


Nice. I'm adding "Well played, LSAC dicks" to my list of LSAT teacher tattoos that I want to get. Love it.


The pertinent evidence here boils down to "the craters could have been volcanic or from meteors. But because they're in a line, they've gotta be all one or all the other. And they're different ages."


Then it leaps to the conclusion "they were probably caused by volcanic events rather than meteorites."


Why are they saying this? Do you see the hanging piece of evidence that was never used? It popped up right at the end. Yep—it's the bit about ages. The author seems to assume that if the craters are different ages, they have to be volcanic instead of meteoric. 


To strengthen, I'm looking for "if they're different ages, they have to be volcanic (and/or, they can't be meteoric)."


A) This makes it possible that a straight line of differently-aged craters can be caused by volcanoes, but it doesn't rule out the possibility that a straight line of differently-aged craters can be caused by meteors. So this strengthens, but not as much as I'd like.


B) This is better. This basically eliminates meteors as the cause of the line of craters—or at least makes it very unlikely, if there's no known natural cause that would do this. I like this one.


C) This is a terrible answer if we're trying to conclude that the craters were volcanic in origin.


D) This either weakens or does nothing. It certainly doesn't strengthen.


E) This does nothing because the argument is trying to rule out meteors altogether, not just one single meteor shower. (The craters are different ages after all; it seems likely that if the line was created by meteors it would have to have been multiple meteor showers.) Furthermore, the "exactly eight" thing makes this answer too narrow to be useful. What if a single meteor shower is known to have created a straight line of 7 differently-aged craters, and another straight line of 9 differently-aged craters? This answer doesn't rule out that possibility, so it sucks.


The best answer is B, because it makes it look very unlikely that the line of craters was caused by meteors. "Well played, LSAC dicks" indeed!


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