Q21 - Which one of the following

[giladedelman]

I was hesitating between A and B. I can understand why B is a correct weaken answer, but why is A not so?

If we apply A (Telescopes of certain types will not perform well unless they have been precisely collimated, a delicate adjustment requiring deftness.) to the stimulus, Newtonian telescopes could be one of the mentioned kind that requires precise collimation, and amateur astronomers could have been testing Newtonian telescopes in a wrong way, making the comparison invalid. Thus, A weakens the conclusion that Exodus is superior than Newtonian telescope.

What am I missing here?

Thanks in advance for your guidance.

[giladedelman]

Thanks for the question.

The argument tells us that Exodus telescopes get clearer images than Newton telescopes. It then concludes that any serious amateur astronomer should buy the Exodus for planetary observation.

(By the way, it does NOT conclude that the "Exodus is superior"!!! Be careful!!!)

So what's the assumption? Well, it seems to be assuming that one ought to choose the telescope that yields clearer images. But what if there are other, more important telescope features?

Answer (B) weakens the argument by attacking this assumption. If image quality is only one of several important qualities, we can't conclude that amateur astronomers should buy the Exodus simply on the basis of its clearer images.

So why is (A) incorrect? Well, look at the great lengths you had to go to in trying to make it work! First of all, the conclusion isn't that the Exodus is superior, so whether the Newton is actually superior when properly calibrated is irrelevant. More importantly, we just don't know whether either of these telescopes is the type mentioned here. So the fact that "certain types" require collimation doesn't pertain to the Exodus-Newton debate.

(C) is out of scope. The argument is about the people who do plan on observing planets.

(D) is kind of a premise booster. We don't care when the observations were made.

(E) is out of scope. Should astronomers buy it or not?

Does that answer your question? Let me know.

[a3friedm]

In addition to what Gilad said, I think answer choice (A) kind of hints you to the direction of answer choice (B).

I loved his explanation, and if collaboration is a factor that is considered when buying telescopes then Image quality isnt the only factor that determines ones choice of telescopes!

[yiwoo0216]

I just have a quick question regarding a minor distinction of the question stem (although I know that the correct answer would probably be the same in either case)...

The question stem is "which one of the following most seriously weakens the argument?"

All the weaken questions I've seen that are true 'weaken' questions mention somewhere in the stem "if true" but this one doesn't.

In this particular question, the answer wouldn't change but in some instances the wording might be tricky and the 'if true' might be a deciding factor between 2 close answers.

My question is, given that there is no "if true" here (assuming it is not a true 'weaken' question) , what is the category that this question belongs to?

Possibly Must Be True?

Any insight would be helpful. Thank you very much.

[tommywallach]

Hey Y,

I can say with total confidence that it makes no difference whatsoever. : )

-t

[WaltGrace1983]

What if the answer choice had said, "Newtonian telescopes are superior in every other way?" This would NOT weaken the conclusion because we are basing the conclusion on "these astronomers' observational findings." Therefore, we would actually have to show why the other stuff IS relevant and that is what (B) does.

Someone correct me if I am wrong but this seems to be getting at the distinction between merely strengthening the conclusion/claim (not our task) and strengthening the argument (which is our task). We need to show WHY the premises don't necessarily lead to the conclusion and thus we need to show why the premises are lacking. Saying, "Newtonian telescopes are superior in every other way," does NOT show why the premises are lacking. Perhaps the ONLY thing that matters is image quality.

[ohthatpatrick]

I think that if an answer said "Newtonian telescopes are superior in every other way concerning planetary observation", we would definitely pick it.

I totally get your point and I think that in a general sense what you're saying is correct, but I want you to realize that you absolutely ARE allowed to weaken an ARGUMENT by simply introducing evidence that makes the conclusion less likely.

The correct answer USUALLY deals with the reasoning, but it doesn't have to. (You can also weaken an argument by discrediting the trustworthiness of the premise)

In essence, we could take any idea that seems to just weaken just the conclusion or just the evidence and still argue that it relates to the reasoning, because assumptions relate to the reasoning and the author "assumes the evidence is trustworthy" and "assumes that there is NOT compelling counterevidence to his conclusion".

Had the author concluded "based only on these observations, an astronomer ought to choose Exodus", then maybe we would need to think more narrowly about how the specific observations failed to pick a winner.

But the author is just saying
"given these observational findings"
which just means "given this piece of evidence"
not "given ONLY this piece of evidence".

By only CONSIDERING this one piece of evidence, the author is assuming that other comparative factors between the two models don't matter. But I wouldn't say that we readers are barred from considering other comparative factors by any language in the argument.

Ultimately, this is a silly debate.