The “Master Argument” of Diodorus and Temporal Determinism

Abstract

Regardless of any doctrinal views of the matter, it is clear that with respect to a wide spectrum of propositions we are not in a position to say whether they are true or false. (E. g., “The President of the U. S. A. in the year 2010 will have been trained as a physician.”) And this is most graphically the case in those matters with respect to which we ourselves deliberate regarding our line of conduct. (E. g., “Smith will do A” in a context in which Smith is endeavoring to decide whether to do A or B.) In such cases, the temptation may come upon us to hold not simply that one cannot yet say whether the statement at issue is true or false, but to hold that the statement does not yet have any truth-value whatever. Although the points at issue may seem to involve only matters of abstract logic, this appearance is deceptive, for important philosophical doctrines are critically involved. Consider the argument:

• (1) All propositions have a truth-value, and these truth-values do not change over time.

• (2) Therefore, propositions about my actions tomorrow were already true (or false) yesterday, and consequently.

• (3) My deliberations and decisions today can have no influence upon my actions tomorrow.