Grounding Experience: Kant's Deduction of The Conditions of Possible Experience

In the second chapter concerning the Transcendental Analytic lies a section entitled "The Deduction of the Pure Concepts of the Understanding", in which Kant attempts to establish a priori grounds for the possibility of all experience. He begins by stating recognizing the absurdity of a priori concepts that relate to objects of experience, saying, “It is entirely contradictory and impossible that a concept should be generated completely a priori and be related to an object although it belongs itself within the concept of possible experience nor consists of elements of a possible experience” (CPR 226-7).

On this note, Kant proceeds assert that although pure a priori concepts can contain nothing empirical, they must “nevertheless be strictly a priori conditions for a possible experience” (CPR 227). Kant goes on to explain that the relation between a priori concepts and empirical reality is that the a priori concepts provide a rational grounding for all the objects of possible experience and serve to make intelligible that which human beings experience through their senses and intuition. In order to prove this, Kant provides a four-part deductive argument concerning the conditions of the knowing subject and how a priori concepts make experience possible for them.

Kant begins by discussing the concept of unity and its role in the creation of a priori concepts that govern all experience. In a section entitled “On the synthesis of apprehension in the intuition”, he explains the way in which the manifold nature of intuitions must be understood before the experience can be made intelligible by pointing out that the manifold representations that are possible of an object must be unified into one temporal representation before the process of understanding can take place. This process he dubs the synthesis of apprehension, and states that “without it we could have a priori neither space nor time, since these can be generated only through the synthesis of the manifold” (CPR 229).

Next, Kant goes on to explain the next step in his argument for a priori principles governing experience, which he refers to as the synthesis of reproduction. This, he explains, involves the recognition of the totality of the aggregate of previous representations in the understanding of a representation as a single concept. He explains this as recognition that the manifold of a certain representation is not due to each individual representation having a particular, distinct identity, but rather are reproductions of a governing concept. Essentially, he is explaining the role that different representations of identical concepts (i.e. counting integers, recognizing that each is the product of successive addition of other representations) is that it reminds the knowing subject of the manifold nature of the representation itself, and that in order to recognize something as having a unified identity, the previous conceptions of that representation must be kept in mind.

In the third section of his argument, Kant explains that the previous two premises coalesce together to form what he calls the unity of rule. Basically, Kant states the next step in establishing a priori conditions for possible experience is the recognition of the a priori concept itself as a general rule for all subsequent representations. He uses the example of the concept of a body, saying, “the concept of a body serves as the rule for our cognition of outer appearances by means of the unity of the manifold that is thought through it.” (CPR 232) If we consider those categorical outer representations that we experience as falling in accordance with a priori rules established for their recognition, then it becomes clear that a priori rules indeed provide the ground for all possible experience by providing a system by which the knowing subject can make their outer intuitions and experiences intelligible. Kant wraps up this argument in the fourth by stating that “the synthetic unity of perceptions [which was outlined in the previous three sections] is precisely what constitutes the form of experience”, thus confirming what he originally posited about the role of a priori concepts in establishing the foundation for all experience.