 Diodorus used this incompatibility combined with the plausibility of (D1) and (D2) to argue that (D3) is false. Assuming (D1) and (D2) he went on to define the possible as “that which either is or will be true” and the necessary as “that which, being true, will not be false”. In this way his argument seems to have been designed to demonstrate that there cannot be any future contingency at all. However, little is known about the way in which Diodorus used his premises in order to reach the conclusion. The reconstruction of the Master Argument certainly constitutes a genuine problem within the history of logic. Various philosophers and logicians have tried to reconstruct the argument as it might have been. It is very likely that the main structure of the argument was close to the argument presented in the next section. (See (Øhrstrøm and Hasle 1995, p. 15 ff.) and (Gaskin 1995) for references to the literature on the Master Argument.)