The Master Argument Supports Diodoran Modalities

Diodorus is a famous Megarian philosopher. He defines modal notions (necessity، impossibility، and possibility) in terms of temporal concepts. These definitions are consistent with his deterministic position. Among his modal definitions what is more discussed is possibility. He defines possible as that which either is or will be. In other words there is no possible thing that never be actualized. This definition is not commonsensical، so he supported his position with an argument called the Master Argument. Nowadays some have tried to reconstruct Master Argument with modern logic. Here we want to peruse two of them، i. e. Prior، Rescher.