Whenever, on the other hand, it is a harder task to argue about the axiom or the proposition than about the thesis, a doubt may arise whether such claims should be admitted or not; for if a man is going to refuse to admit it and claim that it should be argued for, he will be prescribing a harder undertaking than was originally proposed; if, on the other hand, he grants it, he will be convinced on the strength of what is less convincing.