What is a Noumenon? Ask any (philosophy) person on the street, and you’ll no doubt hear how Kant divided the world into the phenomenon and noumenon, and that we can’t know anything about the noumenon, but have to resign ourselves to dealing with phenomenon, things in themselves vs appearances, etc etc.

But even in this dismissive simplification an inconsistency has already emerged. How could have Kant divided the world into two parts and then gone on, with a perfectly straight face, to deny that we could have any knowledge of the second part? Isn’t the very division itself, and the agnostic claim about unknowability, presenting us with knowledge of what is unknowable? That is, hasn’t Kant, at the outset, committed a self-referential contradiction that any philosophy undergrad could spot with a blindfold on: “I know that the noumenon is unknowable”.

The foolish thing would be to think that Kant has missed something so fundamental. So, we should, instead, suspect the simplified account. That turns us back to the original question, then, which is What is the Noumenon? It cannot be what Kant divides the world into in a simple way, the way we would divide a genus into species. All we have at our disposal is the phenomenon, so for the noumenon as a concept to avoid a simplistic self-referential paradox, it needs to be explicated in the terms of phenomenal reality. Obviously, owing to the definitional nature of the division, it is not a phenomenon, but the agnostic claim, and the division itself, need to emerge from phenomena. So, let’s do that.

Qualification

We would be sabotaged right out of the gate if we didn’t put to rest a very common way of talking about the noumenon that is, nonetheless, obviously flawed. That is the noumenon as cause of the phenomenon. Kant does toy with this idea, or manner of speaking, but never when it counts, that is, whenever he is discussing the problem of the noumenon directly. He can’t. Causality, as Schopenhauer points out, is a category only legitimately applicable to phenomenon by Kant’s own admission. Furthermore, once Kant has placed time and space on the side of the phenomenon, it becomes unclear what we mean by causality when it is applied beyond the context of space and, especially, time. It makes no sense, then, to speak of a supra-sensible causality beyond any possible phenomenon. Furthermore, because of the necessary agnosticism on the question, it makes as much sense to say the noumenon is the cause of the phenomenon as it does to say the noumenon is a dancing circus bear named Rodney. Though it would be nice and simple to define the noumenon just as “that which causes the phenomenon”, this would implode the entire Kantian enterprise. Accordingly, what Kant means by “noumenon” is far more complex, and subtle.

Groundwork

But first, let’s lay some groundwork. It’s important, as Kant seems so committed to the idea of the noumenon despite its perilous potential inconsistency, that we set up the background of how the Critique of Pure Reason births the idea alongside the machinery that forms the true focus of the text.

It could be said that Kant becomes committed to the idea of a noumenon in the opening sentences of the Critique of Pure Reason, when he’s first defining the faculties:

“The capacity (receptivity) to obtain representations through the way in which we are affected by objects is called sensibility.” (B33|A19)

So, even in the opening sentences we have an “object” that we are affected by, and our capacity to be affected is called sensibility. Intuition (the product of sensibility) is defined as that in our knowledge that refers to these objects “immediately” (ibid). It would seem the “object” has already been separated from our capacity to experience it. However, reading the inevitability of the noumenon into this opening does a certain retroactive violence to Kant’s mode of expression. The intuition of the sensibility refers immediately to objects of knowledge. Furthermore, though sensibility has been set up as a passive faculty (thus raising the question, passive to what?), our way of being affected, this does not, yet, entail an epistemic gulf between things in themselves and our being affected by them.

From there, the understanding is defined as the reserve of concepts that provide the form of our objects of knowledge, allowing them to relate to one another. So, to offer a simple example, allowing us to count disparate objects as belonging to a single quantity. There is nothing in my pure perception (intuition) of the various objects in front of me to suggest that they could be numerically identical (each being equal to one thing), however I can truly treat apples and oranges equivalently when I am counting fruit. How many “things” is this laptop in front of me? One? Three? Seventeen? Depends on the operation. The play of concepts allows me to see the laptop as a single unity one moment, and then as a complex amalgam of hardware components in the next, and finally onto a dizzying digit expressing the total number of atoms that make it up. My sensory experience of the object does not change through these conceptual shifts, only what the object represents to the conceptual notion of quantity. This conceptual notion of quantity is given ready-made in my perceptual experience, even though there is nothing perceptual about it. It is the conceptual component, the contribution of the understanding.

This is all to say that we can perform arithmetical operations easily on the objects in front of us because we experience objects through the concept of an object in general. The concept of an object in general is amenable to clean mathematical quantization, in a way the flux of multi-sensory perception isn’t. That’s why I can add a phone to a piece of ash and a stone and a power cable. They all partake in the concept of “object” generally, so I can perform arithmetic upon them as generic “objects”, despite them not sharing any more commonality than their being “objects, generally”.

Now, in the classical Kantian maneuver, it’s argued that we couldn’t derive the concept of an object in general from the particular objects appearing to us, because objects as they appear already presuppose an understanding of objects in general. I.e, we couldn’t learn math by counting things we see, because if we’re counting we’re already doing math, and if we were in a state where things appeared to us as uncountable (countability being completely unknown) it’s hard to see how we could learn counting from uncountable things. Thus, the concept of an object in general is given by the mind a priori and our intuitions (perceptions) fall into these demarcations.

Anecdotally, I remember drawing something as a child, and having the epiphany that objects didn’t actually have bold black outlines as they do in comic books. The fact that this was an epiphany points to the fact that there is something truthful in the “black outline” view of visual experience, despite it not being something in our visual experience. The concept of an object is this virtual outline, or what makes it possible, more or less.

Kant then wonders how it is this concept of an object in general could have arisen in such a way that it could apply to perception so ubiquitously. He represents it through the general formula “Object=X”. Now, it’s not enough we have this notion of Object=X, we need to be able to say how it is possible for the world as it is experienced to be so subject to it. In an awesome passage he derives the general concept of an Object=X out of the Cartesian Cogito. It will be instructive to our discussion of the noumenon to see how the proto-notion developed.