I continue explicating my Stufenleiter by distinguishing receptivity from sensibility, which are often conflated in the literature. I argue that the preestablished harmony theories of Leibniz and Crusius, as well as the “hyperphysical influx” Kant ascribes to Plato, involve receptive but non-sensible modes of intuition. I identify significant and underappreciated puzzles afflicting Kant’s notion of sensible affection: Kant has no account of how material objects can affect an immaterial mind, nor any account of how an immaterial mind can sensibly affect itself. I conclude by observing that many of the distinctions I discuss, such as the receptivity/sensibility distinction, track different levels of abstraction and that this can have significant consequences for motivating interpretations. Emphasizing sensibility often motivates phenomenological interpretations (Parsons), whereas semantic or “logical” readings (Hintikka) typically emphasize receptivity. I illustrate the fruitfulness of this diagnosis by distinguishing three different conceptions of the singularity of intuition, each associated with a different level of abstraction: receptive, sensible, and human.

Chapter 1, “Inner Sense as the Faculty for Inner Receptivity”, sets the stage by introducing Kant’s basic model of representation and by defining two pairs of concepts that will guide my analysis: reflexivity and referentiality, on the one hand, and objective and subjective validity on the other. Through an examination of the historical context, the chapter develops an account of inner sense as a transcendental faculty of sensibility, and gives preliminary accounts of central concepts, including affection, sensation, appearance, intuition, perception, and experience. As a result, the chapter suggests that – by analogy with outer sense – inner sense receives inner appearances and yields distinctively inner intuition according to its specific form, i.e., time. The full argument for this claim will be put forward only in Chapter 2. Finally, by considering insights concerning the faculties for desire and feeling from the third Critique and the Anthropology, the chapter develops a broader notion of inner receptivity as susceptibility to all mind-internal causes.

Chapter 2, “Temporal Consciousness and Inner Perception”, offers an interpretation of inner perception as the perception of distinctively inner appearances by drawing on resources from the Transcendental Aesthetic and the Transcendental Analytic (mainly the A-Deduction) of the first Critique. The chapter develops an interactional model of perception with three constitutive aspects: (1) affection through outer sense, (2) synthesis of apprehension through the active faculties of the mind, viz. imagination and understanding, and (3) self-affection through inner sense. Each of these constitutive aspects is shown to define a formal and a material condition of perception. By carving out the notion of transcendental self-affection, i.e., the a priori determination of the form of inner sense through the understanding, the chapter derives the a priori temporal conditions of perception. Applying the general model to the inner case, inner perception is construed as empirical consciousness of inner appearances, based on empirical self-affection.