Critique of Pure Reason – Transcendental Deduction and Third Analogy

Transcendental Deduction

Kant distinguishes between questions of right (quid juris) and questions of fact (quid facti) and demand proof of both. Deduction, refers to if we are right or justified in asserting a claim. We use a number of empirical concepts without the feeling of needing to justify our practice to anyone, because we can appeal to experience which we assume has objective reality. However, with concepts such as fortune and fate, it is difficult to appeal to experience because they do not seem to be tied to it in an obvious way. Many our concepts of human knowledge, seem to be derived from our pure a priori mechanisms of mind. We cannot tie them to experience, so need to be justified if we are going to use them. Kant distinguishes between two studies:

Transcendental Deduction

The explanation of the manner can a priori refer to objects. It focuses of the legitimacy of the concept.

Empirical Deduction

The explanation of the manner of which a concept is acquired through experience and through reflection upon experience. It focuses on how the concept came to be.

We cannot say how the concepts of space and time were acquired through experience. For example, we don’t experience time itself but we do experience time’s affects through sense experience Time and Space seem to refer to objects, without having borrowed anything from them. Instead, they give such representations and intuitions context so we can make them intelligible. Though experience cannot tell us of the conditions of their possibility per se, it can tell us how they are produced. Experience contains two very heterogeneous elements:


Derived from the senses.


How the matter is arranged in order to be intelligible to us. It is derived from the inner sources of pure thought and pure intuition, which are the mechanisms which make thought and intuitions possible.

The deduction of the pure a priori concepts, is impossible to derive from experience because it does not originate in this way. While empirical deduction can tell us how we come to process knowledge, it does not tell us anything about the means that are used in this process.

If I have A, and then have something totally different called B, we do not know anything about the empirical content of A and B. Because of this, we need some way to establish the objective validity of the concept. We don’t know if these concepts are empty, yet we seem to be able to make sense out of them. It seems evident that they must conform to formal conditions of a priori in the mind. However, it is not so evident that the conditions of understanding conform to a synthetic unity, yet this is a necessity if we are to link the two elements in a relationship a priori. There must be a necessity to the link, which follows an absolutely universal rule. While appearance can supply us with cases for rules, they cannot tell us if such rules are necessary.

Third Analogy


All substances, insofar as they can be perceived as simultaneous in space, are in foregoing interaction

Things are simultaneous when one empirical intuition follows another. Thus I might see the earth, then moon. Or conversely, the moon then the earth. Because one object follows immediately after the other, we are justified in saying for Kant, that these objects are spontaneous. When Kant talks about the simultaneous, what he means is the existence of the manifold i.e. the existence of various forms and characteristics at the same place or time. It is the synthesis of the imagination, which gives us the appearance of one form being there while the other is not. Though it does not tell us that these objects are simultaneous. In order to explain this phenomenon hence, we need a concept of it. It cannot be known through experience however.

In the synthesis which allows us to apprehend objects in time, we are indifferent to the manifold of forms. If we were to separate and perfectly separate all of our experiences of an object through time, then cause and effect would cease to exist. It is necessary then for all appearances to exist in a community of interaction with one and other. Without this community of different temporal events, all the objects of our experience would exist spatially distinct from one and other.