CPR: Steps in The Transcendental Deduction (“B” Edition)

Here I’m going to try and pull things together by setting out how the deduction is organized. I’m going to skip the metaphysical deduction, and I’m only dealing with the “B” deduction.

§15.

Combination or synthesis is a spontaneous act of the understanding.

There is a profusion of sense impressions in perception, with nothing intrinsic to them which can supply the combination as such, the grouping together of these impressions into intelligible objects. We cannot sense combination. Our eyes respond appropriately to light, our nostrils to certain kinds of molecules, but the combination of these sensations to form presentations of objects is not this passive receptivity or affection, but rather active interpretation (loosely speaking). Therefore synthesis/combination is not on the side of receptivity but of spontaneity, i.e., the understanding.

Unity of Synthesis

The concept of combination carries with it the concept of unity. Synthesis is combining into one, whereas analysis is breaking down one into many.

§16.

Sensible manifold intuitions, as presentations to a subject, have a necessary reference to the original or pure apperception (the I think)

  1. To think something is to at least be capable of cognizing that one is thinking of the presentation, which is in turn the presentation I, as the subject of this experience.
  2. Therefore, if the I think did not at least potentially accompany every presentation, then there could be presentations that were not thinkable, “which is equivalent to saying that the presentation either would be impossible, or at least would be nothing to me.”

But we know that there are given presentations prior to all thought — these are called intuitions — and these must, therefore — if they are to be anything at all, i.e., if they are to be presentations — have a “necessary reference” to the I think that belongs to the same subject as the subject of the intuitive manifold.

It must be possible to cognize the fact that these presentations are mine for them to be mine at all.

Without the transcendental unity of apperception, a united empirical consciousness of object A is not necessarily linked with a united empirical consciousness of object B. Thus it is only because a manifold of presentations can be combined in one consciousness that there can be a presentation of the identity of consciousness across these presentations. In other words, the I think depends on the reference of the manifold to a single consciousness.

Consciousness must be consciousness of.

§17.

The original synthetic unity of apperception is the condition of the possibility of the understanding

The understanding is for cognizing (or, knowledge of) objects via presentations.
The manifold in intuition is united in these objects.
This uniting is a result of synthesis, which must go along with unity of consciousness (from §16).
Therefore understanding is only possible with this synthetic unity of apperception.

So the “principle of the synthetic unity of apperception is the supreme principle for all use of the understanding“

All intuitions must be subject to the synthetic unity of apperception in order to become objects for me.

§18.

Distinction: Original unity of apperception vs. empirical unity of apperception (unity of empirical consciousness)

The original, transcendental unity of apperception is objective, whereas the empirical unity of apperception is subjective.

This is because it is only through the former that intuitions become objects; empirical unity concerns contingencies only, for example subjective impressions of hot, cold, etc, without fixing an object, which requires the understanding.

But note that this empirical unity does not stand opposed to the transcendtransendental unity, but is derivative of it. That is, if there were not an overarching original unity of apperception, there would be no possibility of any unity even concerning the merely subjective.

§19.

It is the logical functions of judgement that bring any manifold to the objective unity of apperception. It is in judgements that I use the objective “X is Y” rather than the subjective “A feels B to me”.

The unity of apperception is a necessary condition of judgements.

§20.

  1. From §16, “the manifold given in a sensible intuition is subject necessarily to the original synthetic unity of apperception”
  2. From §19, it is the logical functions of judgement that bring any manifold to the objective unity of apperception.
  3. Therefore every manifold in sensible intuition is determined in accordance with one of the logical functions of judgement, insofar as it is brought to a single consciousness
  4. These logical functions of judgement are the categories
  5. Therefore “the manifold in a given intuition is subject necessarily to the categories” [B143]

§21.

The above proof only works for intuition as such; it remains to prove that human intuition specifically rests on the categories.

In other words, so far Kant has proved that the categories have objective validity for sensible intuition in general. Now he has to prove that they have objective validity for human sensible intuition.

§22.

The categories cannot be used for cognizing (knowing) anything except in possible experience (this means transcendentally possible, see Burnham p.75)

Cognition, which is the use of the understanding by means of the pure concepts, is composed of (a) the concept through which an object is thought, and (b) the intuition through which an object is given.

So the categories, as far as they supply knowledge, or enable cognition, are tightly coupled with empirical intuitions. Even when they are used for pure intuitions, the latter must be applicable to empirical intuitions, i.e., pure intuitions are always directly applicable to possible empirical cognition (knowledge).

Empirical cognition (knowledge) is possible experience, so “the categories cannot be used for cognizing things except insofar as these things are taken as objects of possible experience.”

(He reminds us also that these are objects as appearances, and not considered as things in themselves)

§23.

Some clarifications…

Space and time are the forms of sensible intuition.
The categories are the forms of thought.

The categories apply to intuition as such, i.e., to any sensible intuition. But obviously this is neither here nor there as far as we are concerned. For us, “solely our sensible and empirical intuition can provide them with meaning and significance.”

§24.

But it is because the actual sensibility that the categories are applied to is “left undetermined” that they function as “forms of thought”. They are independent of the specific sort of sensibility through which objects are actually given.

But it is through application to our human sensible intuition that the categories gain objective reality, that they are used.

The Figurative Synthesis

And the synthesis that happens in this process, the actual way that categories are applied to objects as combined in the synthetic unity of apperception, is called the figurative synthesis, which is the synthesis of the manifold in intuition as actually given through human sensibility.

Contrast this with the intellectual synthesis, which is the synthesis Kant has been talking about up till now, that is, synthesis of the manifold in intuition as such, i.e., abstracted from human sensibility.

The figurative synthesis can be called the transcendental synthesis of imagination, insofar as it concerns apperception. That is, the figurative synthesis is carried out by the imagination.

Intellectual synthesis took place entirely in the understanding and didn’t require the imagination.

Imagination

Imagination is the bridge between understanding and sensibility. It is the (productive) imagination that does the synthesizing of intuitions in us. And through imagination, the principle of the synthetic unity of apperception is the principle of figurative as well as intellectual synthesis.

Hence the figurative synthesis falls under the same conditions as the intellectual.

§26.

“We must now explain how it is possible, through the categories, to cognize a priori whatever objects our senses may encounter...”

Synthesis of apprehension is empirical synthesis, i.e., the synthesis that enables empirical consciousness.

Synthesis of apprehension = perception

Kant wants to show that…

“the synthesis of apprehension, which is empirical, must conform necessarily to the synthesis of apperception, which is intellectual.

[...]

The spontaneity that brings combination into the manifold of intuition is one and the same in the two cases: in apprehension it does so under the name of power of imagination; in apperception it does so under the name of understanding.“

[B163 footnote]

B160-161:

  1. Space and time are not merely forms but are given intuitions.
  2. Intuitions contain manifolds, so space and time are given intuitions containing manifolds.
  3. So they have the property of the unity of this manifold [don’t understand how this follows]
  4. So the unity of synthesis/combination that Kant’s been on about in the deduction is already given (given priori, that is) as a condition of the synthesis of apprehension.
  5. This synthetic unity is just the synthetic unity already explored up to §20, but considered as it applies to our sensible intuition, i.e., concerning apprehension.
  6. From §20, the unity of the synthesis of apprehension is subject to the categories.
  7. Therefore all synthesis, including specifically the synthesis in our perceptions—perception being the synthesis of apprehension—is subject to the categories.
  8. Experience is knowledge/cognition through perception.
  9. Therefore the categories are conditions of the possibility of experience.
  10. And the categories hold a priori for all objects of experience.

And that’s the transcendental deduction.

The Example of Freezing Water

Kant gives two examples designed to demonstrate what was shown above, specifically, that our actual sensible intuition is subject to categories.

When I perceive the freezing of water, I perceive two states related and thereby united in time. This is the synthetic unity of apprehension. But if I consider this synthetic unity as an a priori condition abstacted from the perception, i.e., the contents of the synthetic unity, then I am considering the synthesis of intuition as such, which is grounded on the synthetic unity of apperception. And the synthesis abstracted is in this case just the pure concept of cause and effect. Therefore the perception of things in time in necessarily subject to the category of cause.

Burnham’s Three Part Breakdown (p.101)

16-23

Unity of apperception is an absolute requirement of experience
Unity of apperception is achieved with respect to intuition as such through a synthesis according to the categories

24

The forms of human sensible intuition also fall under intuition as such.
Space and time as forms of intuition are necessarily subject to the principle of apperception and -> to synthesis according to the categories.

26

Intuitions given in human sensibility in particular are subject necessarily to the categories.