Identity and Substance in Hume and Kant

According to Hume, the idea of a persisting, self-identical object, distinct from our impressions of it, and the idea of a duration of time, the mere passage of time without change, are mutually supporting "fictions". Each rests upon a "mistake", the commingling of "qualities of the imagination" or "impressions of reflection" with "external" impressions (perceptions), and, strictly speaking, we are conceptually and epistemically entitled to neither. Among Kant's aims in the First Critique is the securing of precisely these entitlements. Like Hume, he acknowledges the correlativity of the notions of temporal duration and persisting self-identical objects (i.e., continuant substances). Unlike Hume, however, he undertakes to establish the legitimacy or objective validity of the schematized category of substance and, correspondingly, of the representation of time as a formal unity with duration as one of its modes. This essay formulates Hume's problem and then explores Kant's complex argument for the legitimacy of our concepts of substantial identity and temporal duration, from its origins in his accounts of the forms of inner and outer sense and the transcendental unity of apperception through the Transcendental Deduction of the unschematized category of inherence and substance and its schematized counterpart, substance as permanence, in the First Analogy. This revised version was published online in August 2006 with corrections to the Cover Date.