The Master Argument

The Master Argument was highly influential on Hellenistic debates about freedom and determinism. Diodorus Cronus (Greek, 284 BC) devised it to support his definition of the possible as that which either is or will be true. Diodorus relied on two premises:

‘Every past truth is necessary’

‘The impossible does not follow from the possible’.

He concluded:

‘Nothing is possible which neither is nor will be true’

One guess, less fanciful than most, is that Diodorus reasoned: suppose some proposition is and always will be untrue; then at some time in the past, it was going to be untrue at all later times; from that past truth, it follows that our proposition is untrue; but that past truth is necessary; and so is what follows from it; hence out proposition is necessarily untrue.

Source: The Oxford Guide to Philosophy, 2005

PS: Even I don’t really get it..

>.<