عنوان مقاله [English]
One of the most important epistemological problems is inductive reasoning, inference of a general judgment from instances, and preparing good evidence to confirm it. The problem is, in order to confirm a general judgment, how many and with what quality of evidences will be needed. All of us agree with G1: "A generalization is confirmed by any of its instances". But two paradoxes, called Ravens and Grue, show that agreement with G1 could afflict us with some paradoxes. The paradox of Ravens, discovered by Carl Hempel, shows that a white shoe confirms that all ravens are black. But we know that this is absurd. The predicate "Grue" invented by Nelson Goodman, shows the inadequacy of G1. A thing x counts as Grue if and only if it meets either of the following conditions: x is green and has been examined, or x is blue and has not been examined. The class of Grue things is thus, by definition, made up of just the examined green emerald things together with the unexamined blue things. All examined emeralds – all of them being green – count as Grue. Thus, According to G1, they confirm the hypothesis that all emeralds are Grue. But this is absurd. Because it would mean to say that all unexamined emeralds are blue. This we all believe to be false.