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. (shrink)