Kant’s Critique of Pure Reason: Transcendental Deduction B

Contents:

1. Unity as the Hinge Point of Kant’s Argument
2. In a “Nutshell”
3. The Activity of the Understanding in the Representation of an Object

Kant provided us with a second, entirely new deduction (or proof) of the necessity for the categories of the understanding in the second edition of the Critique of Pure Reason. It attempts to show that Kant’s notion of the “pure concepts of the understanding,” the fundamental categories that condition the modes in which we may possibly understand any object, is a necessary one if we are to have any capacity to understand the world about us at all. As part of his argument, Kant wishes to show that such pure concepts are transcendental in nature. That is, while (a.) they could not have come to us from our sensory experience, they are nevertheless (b.) the necessary ground for our ability to think logically, that is to link concepts together inferentially.

Kant takes himself to have shown that such pure, a priori categories are present in us in his first proof (Transcendental Deduction A), but only from the standpoint of the subject (from the standpoint of our grasp of our “subjective” cognitive processes). In the second, by contrast, he attempts to deduce the objective necessity of the categories by appealing to their logical necessity, that is, by showing that the categories are a necessary presupposition for our understanding to function as it does.

Thus, the two deductions are something like alternating, complimentary buttresses meant to uphold the basic motivation Kant appears to have had in writing the Critique of Pure Reason in the first place. The technique of providing two proofs rather than one unitary account may be an echo of the Aristotelian approach to the soul, where in de Anima II.1 Aristotle gives both formalistic and physicalistic accounts of its relationship to the body.

Unity as the Hinge Point of Kant’s Argument

As in his first proof, unity is the hinge point of his entire argument. Consider that each form of mental perception, intuition, imagination, and understanding, presupposes a unified object. Knowledge and the images that accompany it both require an act of synthesis or unification of the manifold of our sensory experience, a disconnected series brought together by the forms and categorical conditions the mind itself imposes upon it.

All such objects require a synthesis of some sort, and that synthesis must always take place within the framework of a unifying self-conscious awareness (or so Kant argues). Kant provides the example of this unifying activity in relation to drawing a line B138. Arguing from the assumed premise that no object of our perception is of itself connected or unified, he writes of a line that,

To know anything in space (for instance a line), I must draw it and thus synthetically bring into being a determinate combination of the given manifold, so that the unity of this act is at the same time the unity of consciousness (as in the concept of a line); and it is through this unity of consciousness that an object (a determinate space) is first known. The synthetic unity of consciousness is, therefore, an objective condition of all knowledge. It is not merely a condition that I myself require in knowing an object, but is a condition under which every intuition must stand in order to become an object for me. For otherwise, in the absence of this synthesis, the manifold would not be united in one consciousness.

B138

The synthetic unity of consciousness is thus “foundational” as mentioned above, in the second proof, in the sense that it is presupposed by any other unifying act of the mind and as such is the objective condition of all knowledge, in other words, it is a necessary presupposition, an “only if” of all our mental activity.

This leads to the further question of how any of our mental objects, intentional objects in another idiom, can become unified given that they are subject to the original unifying activity of consciousness. What are the conditions, in other words, that govern the way particular objects become unified in our consciousness? Kant’s answer is of course the categories of our understanding and space and time as the forms of our sensible intuition. Without the forms of our intuition or the categories of our understanding no object can be understood.

In a “Nutshell”

But finally, how do we establish that such conditions are the pure a priori conditions of sensibility and understanding and not conditioned by our experience so as to render them merely contingent? Kant’s answer is twofold: first, we must accept that we have no epistemic access to things as they are in themselves; secondly, we must also follow Hume as far as acknowledging that, apart from any transcendental basis for asserting otherwise, there is no a priori ground for any necessary connection in our sensory perceptions and the associations they deliver to us.

That is to say: the senses themselves cannot be taken to deliver any source of necessity from what might be regarded as a realm of pure contingency—the world of experience. If, therefore, we are to have any necessary propositions at all, they must come from within us. The fact that we do have such propositions, whose truth we are compelled to acknowledge and cannot be otherwise (the truths of geometry or formal logic, for example), indicates that the basis for the existence of such propositions must lie within us.

Thus, Kant clears the way for a proof of the transcendental nature of the pure concepts of the understanding. By the above argument it becomes clear that the unifying, synthesizing activity of the mind must necessarily be subject to certain conditions—the transcendental conditions of our understanding that cannot arise from experience alone from which alone necessity becomes present in our though. Only on such a transcendental basis do we arrive at the necessary ground for explaining how necessary propositions can present themselves to us at all.

The Activity of the Understanding in the Representation of an Object

Many of the topics raised by Kant in the second deduction overlap with those of the first, but the text clarifies many outstanding, lingering questions that might be on many readers’ minds. For this reason, the second deduction is likely to make satisfying reading material for those who have been inclined (or compelled?) to make their way thus far in the pages of the Critique. Only the text itself is adequate for the full realization of its benefits, but one point of clarification that Kant brings forward and is particularly worth mentioning, is the extent to which he regards the understanding as exercising its functions.

Let’s consider Kant’s text first. In the opening section of the Second Deduction (Section 15, B 129-130) he writes,

the combination (conjunctio) of a manifold in general can never come to us through the senses, and cannot, therefore, be already contained in the pure form of sensible intuition. For it is an act of spontaneity of the faculty of representation; and since this faculty, to distinguish it from sensibility, must be entitled understanding, all combination—be we conscious of it or not, be it a combination of the manifold of intuition, empirical or non-empirical, or of various concepts—is an act of understanding.

B129-B130

Notice what happens between the faculty of representation and that of understanding. After distinguishing the activity of the spontaneous activity of the senses from that of the understanding, Kant explains how the act of representation and understanding are mutually implicated. As he finally makes clear in the last few lines, any act of combination that results in a representation implies an act of the understanding. A distinguishing feature of such representations is, as Kant goes on to explain in B130, their inherent analyze-ability. Not only that, but it becomes emphatically clear that the work of the understanding is present in the initial formation of our representations:

For where the understanding has not previously combined, it cannot dissolve, since only as having been combined by the understanding can anything that allows of analysis be given to the faculty of representation.

B130

Finally, in B135 he goes on to write that combination,

is an affair of the understanding alone, which itself is nothing but the faculty of combining a priori, and of bringing the manifold of given representations under the unity of apperception. The principle of apperception is the highest principle in the whole sphere of human knowledge.

B135

Further benefit may now be taken, even at the end of such a series of explanations, in pointing out exactly where the circular nature of a priori knowledge, something many readers might have sensed, has its genesis within us. It develops from the understanding’s employment of a priori principles in the very formation of representations themselves. As quoted above, Kant allows that such representations may contain those principles inchoately, beyond our immediate recognition of them.

Apart from the interesting way such an analysis might impact our understanding of the notion of an unconscious mind, as a mind inherently structured according to pure concepts native to the mind’s own mode of understanding, it provides an additional basis for understanding how Kant arrives at the conclusion later on in the text of Deduction B that,

Categories are concepts which prescribe laws a priori to appearances, and therefore to nature, the sum of all appearances, and therefore to nature, the sum of all appearances (natura materialiter spectata)

B163

Indeed, it appears that, as Wittgenstein was later driven to conclude in the final sections of his Tractatus Logico-Philosophicus, in understanding nature, we do, in a sense, come to understand how our mind structures reality–or better yet, how nature might be considered a construction of the mind itself. Going even further, it is possible to see how our reality insofar as we may know it is necessarily determined by concepts native to the mind’s own way of operating within the world.