THE DIALOGUE BETWEEN AL‐GHAZL AND THE PHILOSOPHERS ON THE ORIGIN OF THE WORLD

The philosophers’ third and fourth proofs of the eternity of the woild are both based on the concept of possibility. In the third proof 1 the argument turns around the possibility of the world as a whole. I t can be stated very briefly, as follows : Everyone must admit that at least the possibility of the world’s existence is eternal; for it could never have been impossible and then become possible. But what can possibly exist eternally must actually do so, because, as Ibn Rushd puts it, “what can receive eternity cannot become corruptible” 2, i.e. have a beginning or ending. I t is not clear how this conclusion follows, until we see that the argument rests on a hidden assumption, pointed out by Van den Bergh 3 that the world as a whole is ungenerated. Now everything ungenerated is eternal, because by definition it could never have come into existence or been corrupted. In this case it can be argued: the world is certainly possible. I t has also existed actually at mme time. But if it existed at any time, it must have done so at every time, since it is not subject to generation or decay (al-kaun wu-Z-fasdd) . The assumption made, that the world is ungenerated, begs the whole question at issue, as Van den Bergh has shown. If we substitute ‘(Socrates” for “the world” we can start off with the premise : “the possibility of Socrates’ existence is eternal.” But it is obvious that we cannot prove from this that Socrates is actually eternal. Al-Ghazgli makes this objection, saying quite correctly that eternal possibility does not imply eternal actuality, “for reality does not conform to possibility but differs from it.” 4 He does not see the hidden assumption, that the world as a whole is something ungenerated. Even if he had seen it, he would not have accepted it as a proved fact. The fourth p o o f 5 concerns the relation o€ possibility to matter, inside the world. The philosophers’ argument can be stated as follows. While the world as a whole is ungenerated and uncorrupted, the world in detail is continually changing. Change means the combination of fresh forms in matter, making new things actual. Now every new combination was eternally possible. But possibility requires a substratum, matter, in which the changes of form take place. Therefore this substratum, matter, must also be eternal. This is the essence of the philosophers’ argument. Here a criticism may be offered, which does not occur in Al-Ghazfili. I t seems to me