Q4 - Anne: Halley's Comet, now

[b91302310]

I think answer choice C is also attractive and I am still confused about the said "evidence". How to distinguish the correct answer between answer choices C and D?

[ManhattanPrepLSAT2]

I agree that (C) is also very attractive --

Anne's evidence is that no comet has ever been observed to flare so far from the sun.

(C) says provides evidence that directly opposes Anne's, so what we would need is evidence that comets have been observed flaring so far from the sun.

We don't get that -- rather, we get an explanation for the evidence (the reason no comet like that has been observed is...) and (D) more accurately states this function.

[farhadshekib]

Also, notice that Anne really presents two pieces of evidence (i.e. premises):

i) H. Comet, which is now relatively far from the sun, has recently flared brightly enough to be seen by telescopes; and

ii) This is the only comet, ever, that has been observed that far from the sun.

Conclusion: "such flare must be highly unusual".

Sue responds: "Nonsense" (i.e. Anne's conclusion is false). Why?

i) Usually people do not try to observe comets when they are so far from the sun.

(in other words, she agrees with Anne's first premise that H. Comet is currently far from the sun).

ii) The flare was observed only because an observatory was tracking H. Comet very carefully.

In other words: she agrees, implicitly, with Anne that a) H. Comet did flare brightly enough to be seen by telescope, and b) that H. Comet may be the only comet that has been SEEN to flare so far from the sun.

Sue, however, disagrees with Anne's conclusion.

While Anne concludes "such a flare must be highly unusual", Sue argues that this flare is not necessarily unusual. Rather, no one bothers observing Comet's that far from the sun.

So, it may possible that comet's, when they are very far from the sun, flare all the time - we just don't notice it because we don't look that far.

Thus (D) is correct. We know (C) is wrong because it appears that Sue actually agrees with Anne's evidence, but disagrees with her conclusion.