How Kant conceives of the relation between thinking and perceiving has remained far from clear. On the one hand, he claims that thinking and perceiving (or understanding and sensibility) require distinct and indeed heterogeneous capacities. This claim is crucial to Kant's entire project, since his critique of his Empiricist and Rationalist predecessors depends on it. On the other hand, Kant is equally concerned to show that intuitions, the acts of sensibility, themselves involve the understanding. And this claim is no less crucial: Kant's justification of the possibility of synthetic a priori knowledge demands it. How are these two claims to be reconciled? In my dissertation, I first bring out the force of this question and then address it by proposing a new interpretation of Kant's conception of the understanding.
'Synthesis' is Kant's term for that exercise of the understanding which accounts for the unity of intuition. Most commentators simply assume that, because synthesis is an act of the understanding, and the understanding appears to be defined as a capacity for judgment, synthesis is identical to judgment. But this, I argue, distorts Kant's conception of the understanding. This distortion is reinforced by a complementary distortion in received interpretations of Kant's notion of intuition. Bringing one of these interpretative distortions clearly into view therefore requires addressing the other as well.
I begin, in the dissertation, by discussing the distorted view of intuition. This is the view, widespread among commentators, that an intuition is a part of a judgment in the same way in which a singular term is a part of a sentence. I argue that this view is mistaken for two reasons. First, it anachronistically ascribes to Kant a Fregean conception of judgment, according to which the structure of an atomic judgment is Fa (whereas on Kant's conception a judgment is essentially a compound of concepts, that is, general representations). Secondly, and more importantly, it misconstrues the cognitive function of intuition in Kant's philosophy: An intuition for Kant is the sensory presentation of an object, and this means that an intuition is not a part of a judgment, but rather a distinct mental act.
Since intuitions are not parts of judgments, synthesis ought not to be construed as a kind of judgment. The reason is as follows: According to Kant, synthesis accounts for the unity of intuition. The only plausible way in which judgment could account for the unity of intuition is for intuition to be a part of judgment. But since intuition is not a part of judgment, synthesis must be distinct in character from judgment. This brings to the fore the real challenge of Kant's doctrine: How can the understanding, which appears to be defined as a capacity for judgment, be responsible not only for judgment but also for synthesis, given that synthesis is distinct from judgment?
After making clear how central this problem is to Kant's overall project in the Critique, I offer an account of the understanding that solves it. I argue that the understanding is fundamentally a capacity for the representation of a certain kind of unity (which Kant calls the unity of apperception). This capacity, so characterized, can be distinguished from two different ways in which it can be exercised: (1) in judgment apperceptive unity is represented discursively, that is, by means of relations of subordination among concepts; (2) in sensible synthesis apperceptive unity is represented intuitively, that is, by means of spatio-temporal relations. Thus, on my view, Kant has a more expansive conception of the understanding than is commonly thought.
My argument breaks down into the following steps. In the first part of the dissertation, I discuss the relation between judgment and intuition. After rejecting, in Chapter One, the view that intuitions are parts of judgments, I go on in Chapter Two to present my own positive account, according to which an intuition is the immediate perceptual presentation of an object. In Chapters Three and Four, I argue that Kant's fundamental characterization of the understanding is as a capacity for the spontaneous representation of apperceptive unity and show that judgment must be construed as one of two distinct ways in which this capacity can be exercised. Finally, in Chapter Five, I show that Kant's theory of geometrical construction provides the model for a distinct kind of exercise of the understanding, and I argue that this is the sensible synthesis that is responsible for the unity of intuition. It thus emerges that Kant holds a distinctive view of how human perception is informed by rational capacities - a view that constitutes a genuine alternative to both conceptualist and nonconceptualist positions in contemporary philosophy of perception. (Abstract shortened by UMI.)