Kant’s Tragedy: The Spear and the Heel

The warrior Achilles went into battle with his Pelian spear, which only he could wield. And as everyone knows, he had a fatal vulnerability too: his heel.

In the Critique of Pure Reason, Kant has both a Pelian spear and an Achilles’ heel—and they’re the very same thing: transcendental idealism. Not only is this his weapon in the battle against sceptical idealists—those who doubt the existence of the world around them—but it is at the same time the weakness that guarantees he will ultimately lose. That which allows him to refute the idealist is the fatal flaw which allows others to cancel this refutation by claiming that what he has produced is just another idealism.

No matter how much he protested, Kant was interpreted as a subjective idealist from the very beginning. This was a big motivation for his publication of the second (B) edition, which included the “Refutation of Idealism”.

But it didn’t stick: he continued to be interpreted as an idealist, and more generally as a philosopher of the doctrine of the veil of perception (the world is hidden from us by our mode of accessing it). This is because the price he payed for establishing objective knowledge of the world was to demote space, time, and the objects of experience to “mere representations” which are “in us” (Kant’s words). In thus arguing against universal sceptical doubt he guaranteed the collapse of his popular legacy into the position of the great systematizer of such doubt.

He refers to his target variously as “sceptical idealism,” “problematic idealism,” “empirical idealism,” and sometimes just “idealism”:

By an idealist, therefore, one must understand not someone who de­nies the existence of external objects of sense, but rather someone who only does not admit that it is cognized through immediate perception and infers from this that we can never be fully certain of their reality from any possible experience.

— Critique of Pure Reason (CPR) A368-369

The dogmatic idealist would be one who denies the existence of matter, the skeptical idealist one who doubts them because he holds them to be unprovable.

— CPR A377

I’ll mainly use the term “sceptical idealist”. Think of Descartes and his evil demon or Hume and his “sentiment” of the continued existence of unperceived objects.

So how does Kant’s transcendental idealism work against this? According to transcendental idealism, the objects of experience are just that: of experience. They are not to be regarded as things in themselves, independent of human cognition, but only as things for us. If objects of experience are regarded as things in themselves, then at some point the philosophers realize that our perception and knowledge of them does not measure up to reality, and we are then seen as being forever cut off from the world, doubting its existence.

That needs some unpacking. Looking at a house, I cannot see all four of its external walls, because I have a finite point of view. Generalizing this term “point of view” to encompass all of the particular ways that I perceive according to my faculties, it’s clear that I cannot know and perceive every possible property and aspect of an object at the same time. To achieve that would be to achieve an absolute perception, a view from nowhere. Kant says that this is a chimera, and is in fact an oxymoron: having a point of view is exactly how things in the world can be accessed. I would add that the idea of a perfect, absolute perception is a legacy of theology, and can be safely dropped. And the thing is: when it’s dropped, human knowledge and perception no longer fall short of anything, and cannot legitimately be described as distorting or indirectly representing anything. Perception is direct and knowledge is objective.

Having wrongly presupposed that if objects of the senses are to be external then they must have their existence in themselves, ie. even apart from the senses, he then finds from this point of view all of our presentations of the senses are insufficient to make the actuality of these objects certain.

— CPR A369

It is only when objects are regarded as things in themselves that they are doubtful, because a thing in itself cannot have merely one visible face or a particular colour etc.; we know that other faces and colours could be seen at other times or by other (kinds of) perceivers. And yet that is exactly how we perceive them, therefore—so the argument goes—we have at best a distorted and indirect access to objects. This is where the gap opens up between human cognition and the world, or the world “as it really is” (the “external world”).

In contrast, according to Kant the world around us just is the entire field of possible experience—and from that, no such gap follows. Objects are precisely that which we can perceive and know according to our faculties.

Note that this is not just about what we can see, hear, and touch in everyday life, i.e., moderately-sized dry goods, in the words of J. L. Austin. It goes for viruses and atoms too. Science is empirical, concerning objects of experience as perceived and cognized according to our faculties of representation and understanding, even if we cannot detect them unaided by technology. In fact it’s precisely scientific knowledge that Kant has forefront in his mind when he establishes the objectivity of the a priori categories of the understanding.

The philosophical idea that objects of experience are things in themselves is labelled by Kant with the term transcendental realism, opposed to his transcendental idealism. Somewhat ironically, it is the assumption that things in space and time are realer than real, as super-real—or as Kant put it, supersensible—that leads to sceptical doubt: Descartes claimed to doubt everything except that he was thinking, Berkeley denied that matter existed, and Hume denied that we can rightfully infer that the cup exists in the cupboard when the cupboard door is closed.

Another of Kant’s terms for the sceptical doubt he is arguing against is “empirical idealism,” and this reminds us of the importance of the distinction between the empirical and the transcendental. The empirical is whatever pertains to or is restricted to experience, and the transcendental is whatever exists in us as conditions for this experience. Transcendental philosophy is less about what we know than about what we must have to be able to know things, given that we do.

(This is not only epsitemology, but metaphysics too: when things become things only for us, that’s a metaphysical position, or at least can be interpreted that way.)

From the empirical perspective—that from which we can know things about the world—objects around us are real and lie outside us in space and time. From the transcendental perspective, however—that from which we ask how we can know anything in the first place—objects around us are ideal and are, yes, in space and time, but are also “in us,” as space and time themselves are.

To many readers this is not a remotely satisfactory answer to idealism or sceptical doubts about the external world, because it looks like Kant is just saying even the external world is all in the head anyway so there’s nothing to doubt. If the transcendental is the profound shift in philosophy that Kant says it is, a way of going deeper into human knowledge, and if from that perspective the objects of experience are “in us” and space and time are not real, then doesn’t this mean that the most profoundly truthful philosophy is actually idealist?

My response is something like sort of, but not necessarily. I think we should interpret Kant according to his stated intentions, and work out how his arguments fit with that. In other words, I think Kant can be saved from his tragic fate.

The key is to see the transcendental perspective not as a correction of the empirical perspective, but as a correction of transcendent metaphysics and the sceptical reaction to it. It is not intended to be a superior replacement for science and ordinary experience. It is not saying this is how reality really is, revealing the noumena behind the veil of perception. It is not really about the world at all so much as about us, as experiencers in the world. Transcendental idealism is the doctrine that allows us finally to let go of the myth of absolute knowledge, and respectfully leaves our knowledge of the world intact: empirical realism is not wrong or even naive, and the shift in perspective to the transcendental is required only as a corrective to the philosophical misunderstanding of this indubitable and objective reality. In other words, it is not telling us that the ordinary and scientific descriptions of objects are wrong, that they have to be replaced — it is explaining why speculative metaphysics cannot work regarding these objects, and obversely why sceptical doubt about their existence can no longer find purchase.

But this is only a first step.