Justified True Belief as Knowledge

Extract

After almost a decade, the discussion initiated by Professor Edmund Gettier's provocative paper “Is Justified True Belief Knowledge?” continues. The most recent contribution to this discussion is Professor John Turk Saunders' attempt to counter Professor Irving Thalberg's claim that a principle that Gettier employs in reaching his notorious negative conclusion is unjustified. I am moved to add to the discussion at this time because it seems to me that the principle in question is unjustified. But more fundamentally, Gettier's argument fails because the putative counter-examples on which it rests fail to make their intended point. I shall discuss these claims in turn.

The epistemic principle which I consider unjustified is the one which Thalberg has called the Principle of Deducibility for Justification (PDJ) and which Gettier formulates as follows: “for any proposition P, if S is justified in believing P, and P entails Q, and S deduces Q from P and accepts Q as a result of this deduction, then S is justified in believing Q.”