his contemporaries. One possible reconstruction is as follows: For Diodorus, if a future event is not going to happen, then it was true in the past that it would not happen. Since every past truth is necessary (proposition 1), it was necessary that in the past it would not happen. Since the impossible cannot follow from the possible (proposition 2), it must have always been impossible for the event to occur. Therefore if something will not be true, it will never be possible for it to be true, and thus proposition 3 is shown to be false. Epictetus goes on to point out that Panthoides, Cleanthes, and Antipater of Tarsus made use of the second and third proposition to demonstrate that the first proposition was false. Chrysippus, on the other hand, agreed with Diodorus that everything true as an event in the past is necessary, but attacked Diodorus' view that the possible must be either what is true or what will be true. He thus made use of the first and third proposition to demonstrate that the second proposition was false. Notes References Further reading Gaskin, Richard, The Sea-Battle and the Master Argument. Aristotle and Diodorus Cronus on the Metaphysics of the Future. Berlin, Walter de Gruyter, 1995. Sedley, David. Diodorus Cronus and Hellenistic Philosophy. Proceedings of the Cambridge Philological Society 203, N.S. 23 (1977), P. 74-120. Vuillemin, Jules. Nécessité ou contingence. L'aporie de Diodore et les systèmes philosophiques. Paris 1984. (English translation: Necessity or Contingency. The Master Argument, Stanford: CSLI Publications, 1996. , paperback ). External links with a bibliography on the Master Argument 4th-century BC Greek people 4th-century BC philosophers Ancient Greek logicians Megarian philosophers