6. Surnamed CRONUS, a son of Ameinias of lasus in Caria, lived at the court of Alexandria in the reign of Ptolemy Soter, who is said to have given him the surname of Cronus on account of his inability to solve at once some dialectic problem proposed by Stilpo, when the two philosophers were dining with the king. Diodorus is said to have taken that disgrace so much to heart, that after his return from the repast, and writing a treatise on the problem, he died in despair. (D. L. 2.111.) According to an account in Strabo (xiv. p.658, xvii. p. 838), Diodorus himself adopted the surname of Cronus from his teacher, Apollonius Cronus. Further particulars respecting his life are not known. He belonged to the Megaric school of philosophy, and was the fourth in the succession of the heads of that school. He was particularly celebrated for his great dialectic skill, for which he is called ὁ διαλεκτικός, or διαλεκτικώτατος. (Strab. l.c. ; Sext. Empir. ad v. Gram. i. p. 310 ; Plin. Nat. 7.54.) This epithet afterwards assumed the character of a surname, and descended even to his five daughters, who were likewise distinguished as dialecticians. Respecting the doctrines of Diodorus we possess only fragmentary information, and not even the titles of his works are known. It appears, however, certain that it was he who fully developed the dialectic art of the Megarics, which so frequently degenerated into mere shallow sophistry. (Cic. Ac. 2.24, 47.) He seems to have been much occupied with the theory of proof and of hypothetical propositions. In the same manner as he rejected in logic the divisibility of the fundamental notion, he also maintained, in his physical doctrines, that space was indivisible, and consequently that motion was a thing impossible. He further denied the coming into existence and all multiplicity both in time and in space; but he considered the things that fill up space as one whole composed of an infinite number of indivisible particles. In this latter respect he approached the atomistic doctrines of Democritus and Diagoras. In regard to things possible, he maintained that only those things are possible which actually are or will be; possible was, further, with him identical with necessary; hence everything which is not going to be cannot be, and all that is, or is going to be, is necessary; so that the future is as certain and defined as the past. This theory approached the doctrine of fate maintained by the Stoics, and Chrysippus is said to have written a work, περὶ δυνατῶν, against the views of Diodorus. (D. L. 7.191; Cic. de Fato, 6, 7. 9, ad Fam. 9.4.) He made use of the false syllogism called Sorites, and is said to have invented two others of the same kind, viz. the ἐγκεκαλυμμένος and the κερατίνης λόγος. (D. L. 2.111.) Language was, with him, as with Aristotle, the result of an agreement of men among themselves. (Lersch, Sprachphilos. der Alt. i. p. 42; Deycks, de Megaricorum Doctrina, p. 64, &c.)