Dr William Large
We are tying to find out the meaning of transcendental idealism. We have discovered that it is better not to understand it as the unification, and how could there be such a unification of opposite poles that cancel one another out, of rationalism and empiricism, but the prising them apart so as to find, so to speak, hidden beneath this opposition, which appears to cover every possibility, a third alternative. This third possibility is what Kant calls transcendental idealism. One of the routes into what this might mean is rather convoluted expression a priori synthetic judgement.
One of these terms were already in use before Kant, and which he uses in the traditional way, and that is a priori, which was distinguished from a posteriori. An a priori judgement was one that that necessary and universal, and thus logical, whereas an a posteriori judgement was contingent and grounded in an appeal to experience. The term, “synthetic”, however, was invented by Kant and here we have to introduce the notion of a predicate proposition. When we say something about something, we predicate something to it. Let us use Kant’s example of ‘all bodies have extension.’. The first concept is the subject of the judgement, “body” and the second the predicate of the subject. Now this judgement for Kant is analytic; that is to say, the predicate can be discovered in the subject simply by analysing it. If I understand the meaning of the concept “body”, I know that extension is contained in it.
The other kind of judgement is synthetic. Again to use an example of Kant, the following judgement is synthetic: ‘all bodies have attraction’ . It is synthetic because under the general description of the “body” it adds a predicate that is not to be found by simply analysing the first concept. No matter what I understand by the term “body” I cannot simply deduce the concept “attraction”. This seems clear and simply enough, but where Kant diverges from classical philosophy is in the relation between these new terms and the old ones of a priori and a posteriori. We would think all analytic judgements would be a priori and all synthetic ones a posteriori. Yet this is precisely what Kant’s claim to have discovered a priori synthetic judgements denies. Such judgement could neither be empirical, for they are a priori, nor merely logical, for there are synthetic; that is to say neither rationalism nor empiricism can explain them. The clue for their existence, for Kant, is to be found in what he calls intuition.
The two building blocks of human
knowledge for Kant are concepts and intuitions. An intuition is the
immediate appearance of the object – the table that you see before your
eyes, and the concept is idea or meaning through which you think the object,
‘table’ in general . Although in our mind, we can easily
abstract these two sides of human knowledge, in the absence of either nothing
truly can be known, for without intuitions concepts would be about nothing,
and without concepts intuitions would be chaotic and orderless. To
use Kant’s famous saying, concepts without intuitions are empty and, intuitions
without concepts are blind:
Without sensibility no object would be given to us, without understanding no object would be thought. Thoughts without content are empty, intuitions without concept are blind. It is therefore just as necessary to make our concepts sensible, that is, to add the object to them in intuition, as to make our intuitions intelligible, that is, to bring them under concepts. These two powers or capacities cannot exchange their functions. The understanding can intuit nothing, the senses can think nothing. Only through their union can knowledge arise.(A51/B79)Following on from this quote, we can see that corresponding to intuitions and concepts, there are two faculties of human knowledge: to intuitions, the faculty of sensibility, and to concepts, the faculty of the understanding. For Kant, it is absolutely important, in understanding the kind of beings that we are, that we can only know something through the faculty of sensation; that is to say, that the object must be given to us. There might be other beings (and Kant is thinking of God here) that are able to know things directly through thought (what he calls ‘intellectual intuition’), but we cannot do so. This is a very important limit on the validity of human knowledge. We can think many ideas, but the only ones that have any validity are those that are limited to the sphere of experience, for it is only the conjunction or union of intuitions and concepts that produces legitimate knowledge. As we shall see, Kant’s critique of many of the pseudo problems of philosophy as to do with the illegitimate use of concepts beyond experience.
Having made the distinction between concepts and intuitions, there is one last distinction we have to make, which is the distinction between empirical intuition and pure intuition, since it is the latter that is the proof, for Kant, of transcendental idealism. We already know what empirical intuitions are – they are the things that are immediately present to us, the table, the tree outside the windows, the roofs of the houses, but what can pure intuition? Kant means by ‘pure’ that these intuitions are a priori, but how can this be so when we have just seen that intuitions come from experience? It seems to be a contradiction to say that intuitions can both be empirical and pure.
The contradiction only comes about when we confuse the content of appearance (or matter as Kant calls it) with the form of appearance. The content of appearance is the table, the tree and so on (though remember in actually perception, no intuition is without its object – I always see the table as a ‘table, the tree as a ‘tree’), but pure intuition is not the same as this content. It is, rather, the mode of presentation of this content, how it appears to me, or the manner of appearing of what appears. It is Kant’s argument that appearing cannot be the same as what appears, in other words it cannot be something empirical, and if it cannot be empirical it must be pure, that is to say a priori.
What is or are the forms of pure intuition? If we abstract from the concepts or the understanding, and the contents of sensation, Kant says, then we are left with space and time. Space and time, therefore are the pure forms of intuition. This collides, as with all philosophy, with common sense. Do we not think that space and time are something real, that they are just as much outside of us as the things we see? Behind Kant’s argument is a critique of two other accounts of time and again we shall see that it is a matter of find the third path of transcendental idealism that cuts through the two alternative of classical metaphysics: empirical idealism and transcendental realism. These two accounts of time are respectively Leibniz’s idea that time and space are merely relational concepts that belongs to our ideas of objects, and the other, the Newtonian view, that time and space are something real outside of the manner of appearing of appearances. In other words, that transcendental idealism is neither empiricism or rationalism, but the possibility both obscure in their opposition to one another.
Like most commentators, I will concentrate on Kant’ account of space, since his description of the ideality of time is the same. He needs to show that space can neither be something empirical nor merely a concept, to prove transcendental idealism. Let us first of all look at the belief that space is something real, just like the table or the trees we see. Kant’s argument against this common sense view is quite simply. Space, he argues is the outer form of things for us. In other words, things that are outside of us are always in space (the difference from time, is that this is the inner form of ideas – are memories are not literally in space). To say that space is derived from experience is therefore to beg the question, for the very thing that one is trying to prove, spatiality, is already appealed to in the proof. Secondly, space cannot be derived from experience because of its necessity. Remember that the criterion for the distinction between a priori and a posteriori is necessity. The necessity of space for every appearance is that is possible to imagine space without any appearances, no tree, no house and so, but it is not possible to imagine the absence of space and appearances (of course it is possible to think the absence of space, but it is not possible to imagine that there is something and no space). The argument against the Newtonian view that space is something real (a self-subsisting entity, as Kant calls it) is that this would mean that space were a container, but this container itself would have to contained and so on ad infinitum.
This would seem to imply that space, therefore, was merely a concept of things, and thus would be supported by the necessity of space for the outer appearance. Space would therefore be an analytic concept. Remember, however, the proof of transcendental idealism is the existence of a priori synthetic judgements, and this is why Kant needs to show that space is an intuition (for intuitions are synthetic – they add something to our understanding) and not a concept, which are analytic. This is why most of the arguments in the transcendental aesthetic are against Leibniz.
We would think that there are only two alternatives, for we only know rationalism and empiricism, either space is real or it is a concept. The latter would mean that space were merely an analytic predicate of the concept of a body, in the same way that unmarried man is merely an analytic predicate of the concept bachelor. In other words, Kant needs to show that space is not simply a thought that we associate with objects, but their necessary form of presentation. He does this by showing that how we use pure intuition of space, is not the same as how we use concepts . The intuition of space is unitary, singular and unique. This means that diverse spaces are parts of one and the same Space. The relation between these spaces, and Space is not the same as the relations between the concept Tree and instances of trees. All the diverse parts of space belong to one Space, but trees do not belong to one and the same Tree, therefore space cannot be a concept, and if it cannot be concept it must be an intuition, since these are the only two sources of human knowledge .
But if space is neither something
empirical nor something rational, what is its source? The answer
for Kant is the general form of subjectivity. The necessity of the
mode of presentation of appearance in space and time has its seat in form
of human subjectivity. This is why this necessity is a transcendental
one and not merely logical. For it is quite clear for Kant that they
might be beings other than us who are not so constrained (again we can
think of God) but all rational beings are constrained by logical necessity.
And for the very same reason this transcendental distinction is ideal,
because time and space are not applicable to things in themselves, but
As appearances, they cannot exist in themselves, but only in us. What objects may be in themselves, and apart from all this receptivity of sensibility, remains completely unknown to us. We know nothing but or mode of perceiving them — a mode which is peculiar to us and not necessarily shared by every being, though certainly, by every human being.(A42/B59)Why the mode of presentation of appearances for human sensibility is temporal and spatial is question outside of philosophy. It is, like the appearances themselves, given.
 The first example is taken from The Critique of Pure Reason, whereas the second is from Kant’s lectures on logic, which is referred to by Allison, see Henry Allison, Kant’s Transcendental Idealism (London: Yale University Press, 1983), p. 76.
 We need to underline here that intuition for Kant does not mean the power of the mind by which it immediately perceives the truth of things without reasoning or analysis, rather it is immediate sensation.
 We need to be certain here, as Sebastian Gardner points out, that Kant is not denying that there is a concept of space, but we should not confuse this with the pure intuition of space, must underlie even this concept. See, Sebastian Gardner, Kant and the Critique of Pure Reason, (London: Routledge, 1999), p. 77.
 Kant, in the second edition of The Critique of Pure Reason, also demonstrates the difference between the pure intuition of space and a concept by demonstrating that the infinity of space is not the same as the infinity of a concept.