RainMan said: Meanwhile, there is one more question that I am doubting myself. Some squares are parallelograms Some parallelograms are rectangles All squares are rectangles If the first two statements are true, the conclusion must be: a) True b) False c) Uncertain My answer was b) False, but the given answer is c) Uncertain. I thought that if some squares are rectangles, they definitely can't be all rectangles. Click to expand... You may find the Square_of_opposition useful here. However, I find this question to confused as well as confusing. This is an example of a poorly form question. If it is meant to be in some argument form it fails to be that. In general, two existential premises cannot yield a valid universal conclusion. violet indigo