LSAT 2 | Section 4 | Logical Reasoning: Q17

LR Question 17 Explanation

QUESTION TEXT: Every photograph, because it involves the light rays…

QUESTION TYPE: Sufficient Assumption

CONCLUSION: Nothing can ever be definitively proved with a photograph.

REASONING: Photographs are true in some obvious sense. But since they cannot express the whole truth they are false in that sense.

ANALYSIS: If we could show that definitive proof requires that something be true in every sense (and not false in the sense that it does not provide the whole truth,) then we could prove this conclusion correct.

Sufficient assumption questions involve joining one of the premises to the conclusion.

___________

1. CORRECT. We know that photographs are false in this sense. If this answer choice were true then we could safely conclude that photographs do not provide definitive proof.
2. We might be able to definitively prove something even if the whole truth could not be known.
3. Even so, there might be a way to use a photograph to prove something. For example we could prove that a camera works by taking a picture.
4. We’re trying to prove that we can’t prove anything with a photograph. This does the opposite.
5. Same as D. This weakens the argument.

Recap: The question begins with “Every photograph, because it involves the light rays”. It is a Sufficient Assumption question. Learn how to master LSAT Sufficient questions on the LSAT Logical Reasoning question types page.