Intuition in Kant's Theoretical Epistemology: Content, Skepticism, and Idealism

Kant famously wrote, "Thoughts without content are empty, intuitions without concepts are blind." The traditional reception of Kant understands this claim as a synopsis of his views about semantic content. On the one hand, according to this reading, our concepts and the thoughts they compose would be meaningless without perception, or "intuition," to verify them and thereby provide them with content; on the other, our perceptions would have no structure and would be of no cognitive use without concepts to direct them. Against the traditional reading, this dissertation argues that Kant's many claims about the necessary relations that run between intuitions and concepts are most fundamentally of epistemological rather than semantic significance. Kant's ultimate aim was to articulate the necessary conditions that must obtain for sensibility and understanding, intuitions and concepts, to cooperate in the pursuit of theoretical knowledge of the world. This interpretation is grounded on an analysis of three puzzles that arise around the function of intuition in his theoretical epistemology. The first puzzle arises for Kant's view of the nature of the content of perception. Is perception exhaustively conceptual in structure, or is it at all an independent representational faculty? According to Orthodox Conceptualism, Kant's central argument in the Transcendental Analytic entails that perception is conceptual. It is widely agreed that, in the Analytic, Kant aims to show that certain fundamental metaphysical concepts, called "categories," including the relation of cause and effect, genuinely apply to objects. Orthodox Conceptualism argues that the categories can only be shown to apply to objects if they necessarily structure our perception of objects. Against this orthodox reading, I argue that, in fact, the success of the Analytic presupposes a strong version of Non-Conceptualism. Orthodox Conceptualism saddles Kant with a kind of error theory of categorial judgments, by showing that the categories apply only to our mind's subjective organization of perceptual experience and not to the objects of that experience. Kant is and should be a non-conceptualist about perceptual content. The second puzzle arises when we consider Kant's postulate of actuality, which claims that perception provides necessary and sufficient justification for knowledge of the reality of things. Cartesian external world skepticism challenges this principle by, in part, appeal to an inferential model of perception. On that model we are only ever immediately aware of our own inner representations and then must infer the existence of things external to those inner states. If Descartes is right, then our knowledge of the external world will always be less certain than the knowledge we have of our own minds. How exactly does Kant mean to respond to this challenge and to what extent, if any, is it successful? Traditional interpretations of Kant's "Refutation" of Cartesian skepticism argue that even our knowledge of the temporal order of our own mental states, knowledge of the kind "I saw x, then saw y," depends on our possession of certain causal information about the things that caused those thoughts and which those thoughts are about, namely x and y. While I agree that Kant aims to argue that some form of self-knowledge, which Descartes thinks can be foundational for philosophy, is mediated by our knowledge of the external world, the traditional Causal Reading falls short in a variety of ways. Kant aimed to show that the capacity to have knowledge of our existence as a time-determinable self, in an objective empirical time, depends on our capacity to make true determinations about objects in space. Objects in space, according to Kant, must be used to fix the frames of reference in which empirical time-determinations can be made. So, if it is true that we can have objective knowledge of our own existence in time, then the objects in space that we use to ground those judgments must exist. If the Cartesian wishes to challenge the capacity to objectively determine even our own existence, then he leaves himself no philosophical ground to stand on, nor any way to move forward from the bare bones of his cogito. He also thereby transforms himself into an extreme skeptic. Although Kant cannot answer this extreme form of skepticism on its own terms, I argue that he has systematic resources for dismissing it as a real threat to theoretical philosophy. Extreme skepticism is nothing more than a subject's mere longing for a kind of perspective on her own cognitive situation that is in principle impossible for her to have, given the very nature of cognition. Such a perspective is what Kant would call "noumenal" and is therefore not a genuine question for theoretical reason. The third puzzle arises when we consider Kant's Transcendental Idealism in light of his claims that "noumena" are "merely logically possible." Noumena, by definition, are paradigmatic "empty" concepts, in Kant's sense, insofar as we can never experience them, and therefore have "no insight" into their real possibility. Nevertheless a core thesis of Kant's Transcendental Idealism is that the concept of noumena somehow epistemologically "limits" our empirical knowledge to the realm of "appearances," rather than "things in themselves." Now the puzzle arises: How can a mere empty concept, the object of which we cannot even say is really possible, set any kind of restriction on the scope of our empirical knowledge? I argue that the source of the puzzle lies in "metaphysical" interpretations of the distinction between phenomena and noumena, readings which distinguish either between two worlds with two kinds of objects, or between two kinds of property of one type of object. Dissolving the puzzle, I argue, requires adopting a strongly methodological reading of the distinction, according to which the phenomenal refers to that domain of metaphysical possibility into which we can legitimately inquire, and the noumenal to that space of mere logical possibilities that falls beyond. By distinguishing between the domains of legitimate metaphysically inquiry and metaphysical possibility per se, Kant can consistently demand a theoretical agnosticism about the real possibility of noumena while at the same time showing that the concept of noumena restricts the domain of empirical knowledge