Abstract

Anti-psychologism drove Frege into a kind of Platonism. Anti-psychologism did not drive Kant into any form of Platonism. Why is there this difference? ;The dissertation addresses Frege's and Kant's common opposition to the use of psychological considerations in the philosophy of logic. The preliminary tasks include a discussion of their shared conception of formal logic and a short exposition of Kant's epistemology. Although Kant is an idealist, he is not a psychologistic idealist, and he agrees with Frege that the nature of the basic elements of formal logic, truth-value bearers, cannot be explained by psychological considerations. Such an explanation would have to reduce the essential semantic properties of truth-value bearers to various empirical properties; it would require a naturalistic type-type reduction of truth and intentionality. ;The second chapter documents and investigates the principal reason for Frege's and Kant's anti-psychologism: the irreducibility of semantic properties to empirical properties. Kant's transcendental deduction of the categories is used to construct a Kantian argument against the possibility of a naturalistic reduction of the semantic properties of judgments. Kant's position is contrasted with that of Fred Dretske. While the modern naturalist takes the existence of material things as primitive in order to explain intentionality, Kant, in his Copernican manner, takes intentionality as primitive in order to explain nature. Dretske and Kant thus analyze cognition from opposite ends. The cognition of necessary truths reveals itself to be the decisive issue. ;The third chapter supplies a reconstruction and evaluation of Frege's argument that the nature of truth requires an objective truth-value bearer. Frege criticizes the naturalistic token-token reduction of truth-value bearers to empirical entities. He argues that the eternal truths must have eternal bearers: Platonistic thoughts. This separates Frege from Kant's constructivist epistemology. Frege and Kant agree that the basic elements of logic have essentially non-empirical properties, but they differ on their ontological status. Frege's thoughts are objective, Kant's judgments are subjective