Thomas Bradwardine and Epistemic Paradox

The most famous epistemic paradox is Fitch's paradox. In it, Frederic Fitch offered a counterexample to the Principle of Knowability (PK), namely, that any true proposition can be known. His example is the proposition that some proposition is true but not known. This proposition is not paradoxical or contradictory in itself, but contradicts (PK), which many have found appealing. What is really paradoxical is any proposition which says of itself that it is true but unknown. Thomas Bradwardine, writing in the early 1320s, developed a solution to the semantic paradoxes (insolubilia) based on a closure principle for signification: every proposition signifies whatever is implied by what it signifies. In ch. 9 of his treatise, he extends his account to deal with various epistemic paradoxes. Comparison of Fitch's paradox with one of these paradoxes, the Knower paradox ('You do not know this proposition') explains the puzzlement caused by Fitch's paradox. Bradwardine argues that the Knower paradox signifies not only its own truth, but signifies also that it is not known that it is not known, and so is false, since it is known that it is not known. However, his argument is flawed and a different argument for its falsehood is required.