#14 - Unlike stars, planets do not generate light, but only

[g_lawyered]

I see how I didn't understand answer choice E properly. Thanks for clarifying that up!

[flowskiferda]

Got this right because all the other choices were even more terrible than E but I wasted too much time on this question and I’m still not all that convinced that E is correct–how does the argument ever assume that planets are the only non-light-generating celestial objects? Maybe some of these “other celestial objects” generate light and some don’t. The conclusion would still completely follow if other objects also did not generate light, so long as at least some of those objects did. Imo the argument never assumes that nothing besides planets generates light, it simply assumes that at least some of the “other celestial objects” generate light. Does this mean all of them have to generate light? Absolutely not.
E is a sufficient assumption but not a necessary one. And it seems to me that those “the argument fails to consider…” or “the argument assumes” questions generally have necessary assumptions as the correct answers, as we would have no way of knowing for sure that the argument assumed something unless that assumption were necessary. But the only way the argument needs to assume E to be correct is if we assume that “other celestial objects” refers to only one class of objects that are all the same with respect to whether or not they generate light, but the stimulus never indicates this.

Am I completely misunderstanding this or was this just a crappy question that they tossed in there to make the experimental section long enough? Thanks in advance for any insight!

[ashpine17]

Could an instructor explain this question without using conditional statements? I just got really confused after sentence number 2.

[Adam Tyson]

The evidence in the stimulus is that stars generate light while planets don't, and that there is a lot of other stuff out there besides planets and stars.

The conclusion is that there must be celestial objects that generate light but which are not stars.

The problem, of course, is that there is zero evidence to support this claim. Where did this idea even come from? Isn't it possible, under these facts, that stars are the only celestial objects that generate light? Couldn't all those other things out there just reflect light, like planets do? This is what the argument fails to consider. Maybe all those other things are like planets, instead of like stars.

Here's why answer E is a perfect answer. First, did the author fail to consider this possibility? Absolutely, they didn't think about this. And would that be a problem for the author? Also yes, because if some of those other celestial objects do not generate light, then there's no reason to believe that any of them DO generate light (because "some" includes the possibility of "all.") The author thinks at least some of them have to be like stars, but they might all be like planets, or at least unlike stars.

[ashpine17]

my pre-phase was off
it was that stars were the only objects in the galaxy (celestial or otherwise) that generated light
is that wrong?

[ashpine17]

so answer choice A talks about reflecting light instead of generating light; is that enough to eliminate since it doesn't hit at the issue in the stimulus?

[mkarimi73]

I found (D) enticing but I did not ultimately pick it and went with (E). I also have the same question as the poster above regarding (A). Could we have a reason why (D) can be removed safely from contention as well? I found it enticing because it seem to indicate that "just because there are some celestial objects in the galaxy that are not planets, they could still be stars that generate light"?? Help please?

[Luke Haqq]

Hi ashpine17 and mkarimi73!

Happy to address your questions.

Ashpine17, first you ask:

my pre-phase was off it was that stars were the only objects in the galaxy (celestial or otherwise) that generated light is that wrong?

Your pre-phrase is close, but the word "only" makes it problematic. The conclusion that the author reaches is, "Hence, there are celestial objects in this galaxy that generate light but are not stars." So the author is not assuming that stars are the only objects that produce light but rather concludes that there are celestial objects other than stars that can generate light.

To both of your questions on (A),

so answer choice A talks about reflecting light instead of generating light; is that enough to eliminate since it doesn't hit at the issue in the stimulus?

I also have the same question as the poster above regarding (A).

Yes, "reflecting" puts (A) out of contention. The author's conclusion is about celestial objects that generate rather than reflect light, and specifically objects that are not stars. The sentences in the stimulus before the conclusion, however, don't state anything about non-stars generating light. An answer choice that correctly identifies a flaw in the author's reasoning will get at this new element in the conclusion, as answer choice (E) does. Answer choice (E) states that the author fails to consider that "planets are not the only celestial objects that do not generate light." The author concludes that there must be non-stars that generate light. It might be the case based on the first two sentences of the stimulus, however, that stars are the only celestial objects that generate light. The author doesn't consider this possibility but rather assumes that there must be additional celestial bodies that generate light (or stated with the double negative used in (E), "planets are not the only celestial objects that do not generate light").

To answer choice (D), mkarimi73, you ask,

Could we have a reason why (D) can be removed safely from contention as well? I found it enticing because it seem to indicate that "just because there are some celestial objects in the galaxy that are not planets, they could still be stars that generate light"??

Answer choice (D) states that the flaw is that "there are numerous features that distinguish stars from planets besides the ability to generate light." The author's conclusion is about non-stars that generate light. So you're on the right track in thinking that "they could still be stars that generate light" where the author assumes that non-star objects are doing the generating, but we need an answer choice that speaks to non-stars generating light, which (D) doesn't quite do. It just speaks generically to there being distinguishing features, which isn't especially informative and doesn't address the author's conclusion about non-stars generating light.