Originally Posted by

**rowe** I understand the conditional proof part - after all, if P and R are true, then P -> R is going to be true.

I was more concerned about why we made the extra assumptions of Q and P. What if we assume Q and P, and we still arrive at that conclusion, when really ¬Q is true?

Or is it that, if I select the wrong assumptions, then I will be unable to prove what I want to prove?

And in this case, how do I make the right assumptions? Guesswork? Where are the clues to help me make the right assumptions?