confusion about assumption questions

[manhhiep2509]

Hello experts.

I thought that if an assumption is true it must prove that the conclusion is correct. However, after encountering question 56 in verbal review and taking a look such similar assumption questions as question 39 in OG 13, I has found that my previous interpretation about assumption may be incorrect.

I see that correct choice E of question 56 in verbal review 2 does not prove the conclusion correct, but strengthens it. When negating the choice, I found that the opposite does not disprove the conclusion, but weakens it.

So, I think that a correct choice in assumption need
(1) strengthens the conclusion.
(2) weakens the conclusion when we negate it.

is the interpretation correct?

Thank you.

[tim]

If an assumption is necessary, that does not mean it will prove the conclusion, only that the conclusion will fail if it is not present. So the best way to identify a correct answer for a necessary assumption question is to negate it and watch for the conclusion to become impossible all of a sudden.