CPR: Transcendental Aesthetic III

Last time I was left with the question as to how Kant can say that space and time are certainly not the forms of things in themselves, which is a bigger claim than to say that space and time are a priori forms of sensible intuition and that we can know nothing outside the boundary defined thereby. I’ll repeat what I wrote at the end of the last post: Even if space and time are the subjective forms of sensible intuition, maybe things in themselves exist in space and time anyway. Maybe we have these forms of intuition because underlying reality is structured spatiotemporally.

My vague reaction to this standard objection to Kant’s arguments is that it’s rather pedantic and uncharitable — though I won’t try to explain in detail just how. If we grant his arguments so far (for space and time as pure intuitions), I reckon Kant is justified in claiming that things-in-themselves do not have spatiotemporal properties, or do not lie in space and time, because to say this would be to attribute the forms of sensibile intuition to the wrong domain. That is, it is meaningless or inappropriate to say that things in themselves are in space and time, because this is just not what the forms of space and time are. What they are are conditions for objects, and objects are experiential. To speculate that these somehow apply to things in themselves is like saying that prime numbers in reality might be green. I think maybe I’m interpreting Kant in a sort Wittgensteinian fashion.

This is confirmed in the conclusion of the section on space:

If we depart from the subjective condition under which alone we can gain outer intuition, namely, as far as we ourselves may be affected by objects, the representation of space means nothing whatsoever. [B43]

Talk of things in themselves as being in space and time is meaningless. Of course, one might then say, in the 20th century fashion, that a denial of a meaningless statement is thereby rendered meaningless as well.

Recall from the last post:

Space is nothing but the form of all appearances of outer sense … [B42]

... space is not a form of things that might belong to them in themselves … [B45]

If these are both interpreted as claims to merely negative contentless knowledge of things-in-themselves, then the charge of meaninglessness, or of contradicting his statement that we can know nothing of things-in-themselves, doesn’t stick.

I still feel this is an unimportant problem. Interpreted charitably, Kant is obviously not claiming anything positive about things-in-themselves. One cannot do that, which is exactly why space and time (predicates) do not apply to things-in-themselves, making his seemingly positive statement above quite reasonable.

And remember the question, how are synthetic a priori judgements possible? It is the validity of judgements that is primarily at stake, so, for Kant, to say that space and time concern only appearances is to say that judgements of geometry etc. are valid only for appearances, not for things in themselves.

This seems to be supported just after the previous quote:

This predicate is ascribed to things only insofar as they appear to us, that is, only to objects of sensibility. [B44]

Anyway, first we need to assess Kant’s arguments; so far in these notes transcendental idealism has stood unproved.

Arguments for Transcendental Idealism

I covered the first four arguments in this post. Those occur in the Metaphysical Exposition of the Concept (of space), and seek to prove that space is not not empirical, not a concept, but an a priori intuition (pure intuition). The following arguments are a bit stronger: they seek to show that space and time are forms only of the subject, not of anything in itself.

Geometry [B64-66]

  1. The propositions of geometry (many of them, at least) are synthetic a priori and known with apodictic certainty
  2. These absolutely necessary and universally valid truths
  3. Truths are known either through concepts or through intuitions, both of which can be either a priori or a posteriori
  4. a posteriori concepts and intuitions can supply synthetic knowledge only of empirical truths, so these cannot supply the necessity and univerality required — well, it’s been established that we’re looking for a priori anyway, so anything a posteriori is out
  5. a priori concepts are only ever analytic
  6. Therefore, geometrical propositions derive their truth from a priori intuitions.

Okay, fine, but what next?

  1. Let’s say that the necessity we seek is in the objects in themselves
  2. Then we would have to apprehend this necessity through our access to these things
  3. But experience cannot supply the consciousness of necessity
  4. Therefore if the truths of geometry were true of objects in themselves, they would be contingent truths

C. Therefore the truths of geometry must concern objects as constituted not in themselves, which is just to say constituted by our faculties

But does this actually rule out that things in themselves are in space? It gets pretty close, at least. From 6, we know that geometrical propositions about things in themselves cannot be true. And from 10, we know that whatever is true of things in themselves, it is certainly not geometrical propositions.

Transcendental Realism Turns Empirical Reality Into An Illusion [B70-71, Proleg 291]

When “we attribute objective reality” to the representations in space and time, “we cannot prevent everything from being thereby transformed into mere illusion.”

This is what allows Kant to argue against idealism and scepticism, which I went in to in the last post (I think it was the last one). Let’s have a look at the Prolegomena:

The senses represent to us the paths of the planets as now progressive, now retrogressive; and herein is neither falsehood nor truth, because as long as we hold this to be nothing but appearance we do not judge the objective nature of their motion. But as a false judgement may easily arise … [when] this subjective mode of representation [is] considered objective, we say they appear to move backward; it is not the senses however which must be charged with the illusion, but the understanding, whose province alone it is to make an objective judgement on appearances. [Proleg 291]

But if I venture to go beyond all possible experience with my concepts of space and time – which is inevitable if I pass them off for qualities that attach to things in themselves (for what should then prevent me from still permitting them to hold good for the very same things, even if my senses might now be differently framed and either suited to them or not?) – then an important error can spring up which rests on an illusion, since I passed off as universally valid that which was a condition for the intuition of things (attaching merely to my subject, and surely validfor all objects of the senses, hence for all merely possible experience), because I referred it to the things in themselves and didnot restrict it to conditions of experience. [Proleg 292]

When space and time are taken as transcendentally ideal, our knowledge of objects in space and time is thereby guaranteed.

Space and Time are Relational [B66-68]

Everything we know through intuition is nothing but relations But things in themselves cannot be known relationally Therefore the representations of outer sense can contain nothing but the relation of an object to the subject

This seems to be saying that objects just are relations, which is difficult to grasp. What does this mean? [Adorno]

A Theological Argument [B71-72]

I’m going to skip that for now.

The Shared Form Alternative

I said I was going to look into this after giving the arguments, but I feel like forging on into the Analytic right now. The shared form alternative to transcendental idealism – such that the subject and things-in-themselves share the forms of space and time – isn’t in the CPR itself (it’s an objection to Kant’s arguments), so maybe I’ll address it when I come to write a paper on transcendental idealism, or maybe I’ll return and write more here once I’ve got further on.

What was the question again?

How are synthetic a priori propositions possible?

The Transcendental Aesthetic goes some way to answering this. By proving that our experience of objects is conditioned by pure formal intuitions of space and time, Kant shows that we can obtain synthetic knowledge, e.g., in physics, owing to some faculty which is effective as a condition of the experience of objects. Most agree – as Hume did – that judgements about experience are synthetic, that is, can supply new knowledge, but Kant has shown that this knowledge cannot be derived entirely from experience and must depend on intuitive forms.

This establishes part of the puzzle. The Aesthetic is concerned with sensibility, which provides the objects of knowledge – although it doesn’t answer the question of how these objects become the content for knowledge as such (understanding), which is addressed in the Analytic. So the Aesthetic has demonstrated how, just with regard to the sensibility, synthetic a priori knowledge can be provided with its objects.

Essay Questions

I’ll just repeat the same questions from last time.

  1. In the Transcendental Aesthetic, Kant attempts to prove that space and time are subjective conditions of human sensibility, not features of things in themselves. How does this argument work? Is it successful? (BLook, paper 1)
  2. How does transcendental idealism differ from Berkeley’s idealism? How are they related?
  3. In Kant, the primary qualities are given through intuition. How does he deal with the secondary qualities? What is their relation to the cognizing subject and the thing-in-itself? This is from “photographer”, here “The discussion of secondary qualities occurs in A28-29/B44-45, and A45/B62; but really comes to a head in B69-70. There’s some further discussion in A258/B313-314” B35 too? Secondary qualities are given to us in sensation, and primary qualities are supplied by us. Is this right? Is it a paradox?
  4. How does TI combat scepticism?
  5. What role does the transcendental aesthetic play in Kant’s overall argument?