This paper gives an interpretation of Kant's argument for transcendental idealism in the Transcendental Aesthetic. I argue against a common way of reading this argument, which sees Kant as arguing that substantive a priori claims about mind-independent reality would be unintelligible because we cannot explain the source of their justification. I argue that Kant's concern with how synthetic a priori propositions are possible is not a concern with the source of their justification, but with how they can have objects. I (...) argue that Kant's notion of intuition needs to be understood as a kind of representation which involves the presence to consciousness of the object it represents, and that this means that a priori intuition cannot present us with a mind-independent feature of reality. (shrink)