Kant’s Prolegomena

Immanuel Kant Prolegomena to any future metaphysics that will be able to present itself as a science Tr Peter G. Lucas Manchester University Press 1953 (Original, 1783)

There is also an on-line translation by Jonathan Bennett that I quote, except – as noted when it happens – where it diverges from the above.

Kant’s work is intended to supplement his Critique of Pure Reason.

Main Transcendental Question: First Part: How is Pure Mathematics Possible?

Note I

The propositions of geometry aren’t mere fantasies that might have nothing to do with real objects. Pure mathematics, and in particular pure geometry, is objectively valid, but only in application to objects of the senses. When we represent such objects through our sensibility, we represent them not as they are in themselves but only as they appear to us. So they must have any features that are conferred on them by the form of our sensibility—and in particular they must be in space, because space is simply the form of all outer appearances. Outer appearances are possible only through sensibility, the form of which is the basis for geometry; so outer appearances must conform to what geometry say about them. If the senses had to represent objects as they are in themselves, the situation would be quite different. For then the facts about our representation of space would provide no guarantee about how things are in reality. The space of the geometer—a mere representation—would be a fiction with no objective validity, for there would be no reason why things should have to conform to the picture that we make of them in advance of being acquainted with them. But if this picture, or rather this formal intuition, comes from the essential nature of our sensibility, through which objects must be given to us, and if what this sensibility represents aren’t things in themselves but only their appearances, it then becomes conceivable—indeed undeniable—that all outer objects of the world of the senses must agree exactly with the propositions of geometry. …

  • all objects in space are mere appearances, i.e. not things in themselves but representations of our sensible intuition; and
  • the space the geometer thinks about—space in thought, we might call it—is just a form of our faculty of sensible representation.

Note II

Anything that is to be presented to us as an object must be given in intuition. But all our intuition happens through the senses—the understanding doesn’t intuit anything. Now,we have just seen that the senses never ever enable us to know things as they are in themselves; all we encounter through the senses are the appearances of things; and these appearances are mere representations of sensibility.

… Idealism says this:

Only minds exist, and the other things we think we perceive are only representations in us, with no external object corresponding to them.

I say the contrary:

Things are given to us as objects of our senses, existing outside us, but we know nothing of what they are in themselves; all we know are their appearances, i.e.the representations they cause in us by affecting our senses

So I say that there are bodies outside us—i.e. things of whose nature in themselves we know nothing, knowing them only through our representations of them. We call such a thing a ‘body’, meaning ‘the appearance to us of an unknown thing which is nevertheless real’. Can this be called idealism? It is the very opposite of it!

Appendix:On what can be done to make metaphysics actual as a science

On a sample of a judgment of theCritiqueprior to its examination

This judgment occurs in an·anonymous review in the Göttingen Scholarly News for January 1782. . . .[which Lucas credits to Christian Garve and which led to Kant’s work on morals].

…. He seems to have missed entirely the real point of my enquiry.

Wanting to position himself so as to set the whole workin a light that is most unflattering to its author, doing this easily without putting any work into it, Reviewer begins and ends by saying: ‘This work is a system of transcendental (or, as he translates it, of higher) idealism.’

Footnote: Higher’—no way! High towers, and metaphysically-great men that resemble them, are not for me—there is usually too much wind around them! My place is the fertile bottom-land of experience; and the word ‘transcendental’—whose meaning was so often explained by me but not once grasped by Reviewer (so carelessly has he looked at everything)—doesn’t signify something that goes beyond all experience, but something that does indeed precede experience a priori, but whose role is simply to make knowledge through experience possible. If these concepts step beyond experience ,their employment is termed transcendent, as distinct from their immanent use, that is, their use limited to experience. Don’t confuse ‘transcendent’ with ‘transcendental’·. All misunderstandings of this kind have been adequately guarded against in the work itself, but it suited the reviewer’s turn to misunderstand me.

The thesis of all genuine idealists from the Eleatic school to Bishop Berkeley is contained in this formula:

All knowledge through the senses and experience is nothing but sheer illusion, and only in the ideas ofthe understanding and reason is there truth.

The principle that governs and determines my idealism throughout is on the contrary:

All knowledge of things through unaided pure understanding or pure reason is nothing but sheer illusion, and only in experience is there truth.

This is precisely the opposite of the former, genuine idealism.So how did I come to use this expression for a completely opposite purpose, and how did my reviewer come to see genuine idealism everywhere?


My so called idealism (properly: critical idealism) is thus of a quite special kind, in that it:

overthrows ordinary idealism; and through it all a priori knowledge, even that of geometry, first receives objective reality; and even the most zealous ordinary  realists couldn’t have claimed that, because they lacked my demonstrated ideality of space and time—·that is, my proof that space and time are forms of our sensibility.

In these circumstances I would have liked, so as avoid all misunderstanding, to name this concept of mine differently; but I can’t very well alter the name totally. So I may bepermitted in future to call it ‘formal idealism’ (·as I did on page 52·) or, better, ‘critical idealism’, to distinguish it from the dogmatic idealism of Berkeley and the sceptical idealism of Descartes.

My Comments

Kant seems to me to be arguing that all apparent knowledge of an external world must be based on some sort of ‘assumptions’, with those about space and time being particularly important.

Kant may have assumed that everyone does actually perceive space and time in the same way. He may have thought that our notions of space and time were reliable, and not subsceptable to empirical challenge. But, if so, he doesn’t seem to argue the case, and his work can still be made sense of despite such a possible delusion.

On the other hand, his use of language does seem to invite the assumption that he thinks that the objects of appearance always correspond to real bodies, which would be an error. But we could surely read past any such error. For example, we may suppose that the correspondence between bodies and objects is not necessarily always one-to one, but may be many-to-many. We may also think of a rainbow as an object of the senses that challenges the naive view that we might have thought that Kant was advocating.

[Happy to have my attention drawn to any quotes by Kant on this point.]

Dave Marsay


%d bloggers like this: