Paradox

120 A BRIEF HISTORY OF THE PARADOXsary. The impossible does not logically follow from thepossible. What neither is presently true nor will be so ispossible.” Having noticed this conflict, Diodorus used theplausibility of the first two to prove the following: “Nothingis possible which is not presently true and is not to beso in the future.”(Epictetus 1916, II, 19, 1-4)Epictetus goes on to describe how some philosophers rejectother members of the triad. His presentation is the fullymodern one of presenting a paradox as a small set of propositionsthat are individually plausible but jointly inconsistent.This style of presentation is more economical than characterizinga paradox as an argument. If we count paradoxes interms of distinct arguments, Diodorus’s three propositionswould constitute three paradoxes instead of one.Although we know the premises and conclusion ofDiodorus’s master argument, we do not know the steps thathe used in his proof. His contemporaries appear to haveconceded that the conclusion follows from the premises.For they try to resist Diodorus by rejecting his premisesonly. This has stimulated many scholarly attempts toreconstruct the master argument of Diodorus Cronus.Frederick Copleston (1962, 138) suggests the argumentwent like this:1. What is possible cannot become impossible.2. If there are two contradictory alternatives and one hascome to pass, then the other is impossible.3. If the nonoccurring alternative had been possiblebefore, then the impossible would have come out ofthe possible.