My thesis offers an original reading of Kant’s theory of cognition and the body’s role in it. In the Critique of Pure Reason and the Metaphysical Foundations of Natural Science, Kant’s subject is shown to cognize, and be cognized, through embodied activity in the material world.

I begin by demonstrating Kant’s rejection of all-mental accounts of cognition. Neglecting the body leads to the dissolution of subjects, objects, and any cognitive relation between them. I show that Kant provides an alternative account in terms of embodied activity, focusing on three cases. First, the unifying structures required for sense perception could not be applied without embodied activity. Second, empirical self-consciousness depends on embodied activity in relation to objects in space. Third, scientific knowledge is made possible only through bodily activity, which reveals the causal forces constituting matter. In all three cases, the body is shown to have an active role in determining experience.

I then investigate the implications of my reading, providing a new interpretation of Kant’s transcendental idealism – the causally active body is a transcendental condition of experience. I show how this contrasts with not only traditional readings of Kantian cognition as conditioned entirely by the structures and activity of the mind, but also less traditional readings which ascribe a cognitive role to the body only by stripping away its material properties. Even many contemporary non-Kantian accounts distinguish between the mind which acts in cognition, and the body which only passively receives causal affects. Developed in tandem with a robust metaphysics of matter as endowed with causal activity, Kant’s account of the active body overcomes this mind-body distinction. Cognition is more thoroughly embodied than is commonly thought.

I finish by sketching an approach to Kant’s account of life and freedom. I suggest that the transcendental status of the body in the theoretical realm paves the way towards a freely acting subject in the practical realm. Through casting the body as the actor in cognition, Kant provides the resources for a full characterization of the human subject.