Every photograph, because it involves the light rays that something em

Question

Every photograph, because it involves the light rays that something emits hitting film, must in some obvious sense be true. But because it could always have been made to show things differently than it does, it cannot express the whole truth and, in that sense, is false. Therefore, nothing can ever be definitively proved with a photograph.

Which one of the following is an assumption that would permit the conclusion above to be properly drawn?

(A) Whatever is false in the sense that it cannot express the whole truth cannot furnish definitive proof.

(B) The whole truth cannot be known.

(C) It is not possible to determine the truthfulness of a photograph in any sense.

(D) It is possible to use a photograph as corroborative evidence if there is additional evidence establishing the truth about the scene photographed.

(E) If something is being photographed, then it is possible to prove definitively the truth about it.

gmatexam439 · Accepted Answer

Every photograph, because it involves the light rays that something emits hitting film, must in some obvious sense be true. But because it could always have been made to show things differently than it does, it cannot express the whole truth and, in that sense, is false. Therefore, nothing can ever be definitively proved with a photograph.

Which one of the following is an assumption that would permit the conclusion above to be properly drawn?

(A) Whatever is false in the sense that it cannot express the whole truth cannot furnish definitive proof. - Correct. The argument states that since the photograph can't express the complete truth, thus, it is false. Since it is false, we can't definitely prove anything. Similarly this option states that whatever is false cannot be used to prove anything. This matches the argument word by word 
(B) The whole truth cannot be known. - Irrelevant. We are worried about whether the photograph can explain the complete truth 
(C) It is not possible to determine the truthfulness of a photograph in any sense. - In the argument we are talking about the truthfulness of an object and NOT the photograph. Thus this option reverses the causality 
(D) It is possible to use a photograph as corroborative evidence if there is additional evidence establishing the truth about the scene photographed. - Okay. This is a mere fact which is irrelevant with respect to the argument at hand 
(E) If something is being photographed, then it is possible to prove definitively the truth about it. - Irrelevant

Bunuel · Answer

OFFICIAL EXPLANATION

The author argues that since a photograph can be deceptive it can never express the whole truth. Therefore, it can never be used to prove something. The assumption needed to connect these two sentences is that if something cannot express the whole truth then it cannot prove anything. The answer, therefore, is (A).

The other choices are easily ruled out. As to (B), the argument does not state that the whole truth cannot be known, merely that it cannot be known  through  a photograph. Choice (C) is similarly flawed. The argument does not state that a photograph cannot express the truth in  any  sense, merely that it cannot express the  whole  truth. (Again, beware of absolute statements.) Choice (D) is a reasonable assumption to make, but it is not relevant to the argument. Finally, choice (E) contradicts the argument.

Sanjeetgujrall · Answer

I selected the answer as C which appears to be wrong. Can someone tell how?

Applying negation on option C:  It is possible to determine the truthfulness of a photograph in any sense.   which breaks the conclusion. Hence shouldnt C be right?

nightblade354 · Answer

Hi Sanjeetgujrall , Let's analyze the question: Every photograph, because it involves the light rays that something emits hitting film, must in some obvious sense be true. But because it could always have been made to show things differently than it does, it cannot express the whole truth and, in that sense, is false. Therefore, nothing can ever be definitively proved with a photograph. Our conclusion is in dark blue, while our premise is in light blue. I think this is where you became confused. (C) talks about the premise, its truthfulness, but doesn't talk about how we can use the photo as proof. Does truthfulness = definitive proof? No. (A) does this. This is an assumption question, and you are correct to negate. Here is a link to some more detailed explanations if this isn't clear: https://www.manhattanprep.com/lsat/foru ... t1310.html Which one of the following is an assumption that would permit the conclusion above to be properly drawn? (A) Whatever is false in the sense that it cannot express the whole truth cannot furnish definitive proof. (C) It is not possible to determine the truthfulness of a photograph in any sense. Does this help?

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Every photograph, because it involves the light rays that something em

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Every photograph, because it involves the light rays that something em

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