This is what is supposedly his claim:

My noumenal self is an uncaused cause outside of time, which therefore is not subject to the deterministic laws of nature in accordance with which our understanding constructs experience.

How can he say that if a noumenal self has to exist in nature and be bound to body that exists in nature? Also, if his noumenal self is free then so does 7 billion other people's, which is not the case because they all live in a societal structure where everyone has freedom that comes with a bunch conditions as to what is forbidden.

  • I'm slightly confused by the manner in which the question is formulated. The quote from the SEP (plato.stanford.edu/entries/kant) says the noumenal self is not subject to the laws of nature, but you immediately state to the effect that "a noumenal self has to exist in nature and be bound to [a] body that exists in nature". Do you want help (a) understanding the quote or (b) Kant's view of the noumenal self that functions in morality or (c) something else?
    – virmaior
    Commented Jul 8, 2015 at 5:07
  • 1
    Trying to understand the validity of his logic. How can the noumenal self function in nature without existing in it? Just makes no sense.
    – btrballin
    Commented Jul 8, 2015 at 5:48
  • Where does Kant assert that the noumenal self exists in nature or is bound by the body?
    – virmaior
    Commented Jul 8, 2015 at 6:05
  • Well I mean, how else can the noumenal-self function if its presence is not in nature? Wirelessly from outer space?
    – btrballin
    Commented Jul 8, 2015 at 7:01
  • 1
    @btrballin: You seem to implicitely presuppose some kind of realism of "nature" in the sense of an appearance/phenomenon as being prior to the noumenal self which shall be inherited by it. This is a critical misunderstanding of the connection between noumena and phenomena. Kant explicitely tells us that we cannot possibly understand this connection, hence we have to be agnostic towards it. You are not. Therefore your argument seems fallicious/not valid.
    – Philip Klöcking
    Commented Mar 30, 2016 at 8:17

2 Answers 2


Kant's distinction between the noumenal and the phenomenal in his *moral philosophy** is both difficult to follow and integral to his moral thought. Moreover, Kant's use of terms like "nature" and "understanding" have definitions that are not intuitive if we are working from the standard English words.

I think it's easiest to understand it if we start with what Kant wants in a moral theory. Roughly speaking, Kant is hoping for a theory where the moral self using universal reason is able to decide what it morally ought to do and then where the self has the freedom to will this action.

One simple dictum that captures this is "ought implies can." Kant thinks we can know what we ought to do. And then he thinks we can do it. So if we know murder is wrong, Kant thinks we can always in every circumstance do what is right.

But considering he is writing after Descartes, this is clearly going to be difficult to square with Newtonian mechanics -- where everything appears to be explained by the laws of physics. Kant's solution in his metaphysical works. Put simply, everything was explained in terms of nature and its subsequent determinism.

Kant's epistemology hinges on a distinction between knowledge and reason and then things, sensibles, and objects. Put simply, we do not understand things as they; instead we receive them as sensibles through the forms of sensibility (space and time) and then know them as objects through the categories of the understanding. Nature is roughly speaking synonymous with determinism for Kant, which is one of the categories to which our understanding is always subject.

But reason does not function through the categories or the forms. Instead, reason is free. In this way, it lies outside the world of determinism. But the freedom comes at a price of being in a different realm than the phenomenal, which Kant calls the noumenal (derived from the Greek word nous which means mind). The moral self for Kant is the self that is noumenal and that can act freely unbuffetted by the deterministic world.

This is the background apparatus for answering your question.

On Kant's view, the self as a moral self is not in the world of nature. Instead, the self is in a world where it is free. And the reason why we don't see that is that we cannot see it since it is not a phenomenon. In fact, on most interpretations of Kant's moral theory, we can never directly perceive than act is moral, because we can only see and comprehend our world in terms of the forms and categories and encounter others regularly under these.

But Kant asserts that we must have this form of noumenal self. He makes very different arguments for this depending on where in his moral works you are reading. In the Groundwork, he claims he can prove this. In the Critique of Practical Reason, it becomes more a fact of reason that this is true. And in later works, the picture gets complicated as he handles cases of habit.

There are certain semi-cartesian features in Kant's account:

  1. he shares a deterministic picture of the sensible universe.
  2. he shares a belief in the superiority of rationality over the deterministic natural animal
  3. he has a problem connecting this account to the physical domain.

Where he differs from Descartes is in what is called the "Copernican revolution" whereby he looks at our understanding in a different way that hints at a cognitive faculty that has power over the world that we perceive. (note that the domain of its power is the "world" which here refers to a concept in the mind). Basically, Kant turns to the mind in a different way than Descartes -- informed by and accepting Hume.

Kant evades in part the question of how the moral self can interact with the world by making claims about the moral self that take it out of the world of our perception -- i.e., what we see is phenomenal, what we are as free creatures is noumenal. How the two meet is also beyond our ability to know, because knowing is the application of forms and categories to things (and we cannot know the things directly).

Note that we are not required to agree with Kant. If you're a reductionist physicalist, then his theory probably won't work for you in the standard form. But there are contemporary appropriations of Kant that might, such as Christine Korsgaard's constructivism -- whereby she believes we are committed to Kantian principles of agency insofar as we are agents. She does some rather elaborate footwork to keep parts of his ethics while jettisoning his account of metaphysics across her texts Sources of Normativity and Creating the Kingdom of Ends.

  • I know what Kant means with noumenon. But I cannot imagine what a "noumenal self" is. Literally it would mean the person as a thing-in-itself. Can you explain your usage of the term? You write "we must have this form of noumenal self".
    – Jo Wehler
    Commented Jul 8, 2015 at 22:50
  • I don't agree with your understanding of noumenon in Kant.You identify the noumenal with thing-in-itself. But there's little reason to do so (en.wikipedia.org/wiki/Noumenon see Palmquist). To give the simplest possible answer, yes, things in themselves are inaccessible but that does not make them noumenal. Things as brought under the manifolds of sensibility are perceivable and as brought under the categories are renderable in our understanding as objects. But the moral self is not for Kant understandable (where understandable is a technical term, not the lay term).
    – virmaior
    Commented Jul 9, 2015 at 0:08
  • But it is not understandable precisely because it is not phenomenal. Instead, it is noumenal. But things-in-themselves are not perceptible or understandable for a different reason, namely that perceiving them and understanding them is no longer to refer to them as things in themselves. Thus, thing-in-itself refers both to a metaphysical type of entity, a thing, and to mode of inaccessibility under the description "in itself"
    – virmaior
    Commented Jul 9, 2015 at 0:10
  • The person as a moral rational being is also inaccessible to our understanding. But this is because the self is noumenal as opposed to phenomenal in its nature. This is crucial to as Conifold notes the third antinomy. It's also a major part of Kant's arguments throughout his moral philosophy.
    – virmaior
    Commented Jul 9, 2015 at 0:12
  • In Critique of Pure Reason, B310, Kant writes: "Now the concept of a noumenon, that is, of a thing which can never be thought as an object of the senses, but only as a thing in itself ..." In my opinion, this statement identifies both concepts. At least, it considers noumena a subclass of things-in-itself.
    – Jo Wehler
    Commented Jul 9, 2015 at 4:55

Kant argues in Critique of Pure Reason (resolution of the third antinomy) that while free will can not insert itself into empirical causal chains ("nature") it can influence causal chains in their entirety from an atemporal beyond, and then watch them deterministically play out as appearances in time. He can do that because he takes time, like "nature", to be merely an artifact of our perception that has no bearing on things in themselves, like self or free will. So Kant's freedom is not a sequence of free decisions taken in "nature", but an atemporal Decision that has a part in shaping "nature" itself. This is fantastic, but at the end Kant limits his argument to merely demonstrating logical consistency of (atemporal) free will with causal determinism (of appearances), not providing an actual theory of it. Should we grant at least that?

Ralph Walker objected that then the appearances influenced by self's free will must include those from before birth and empirical actions of other selves. The latter contradicts free will of other selves. Is there a way to save Kant's limited argument? Yes, but only by making it even more fantastical. One way is to endorse Berkeley's solipsism and claim that a self has the whole world of appearances all to itself. A slightly better choice is to claim that selves can influence not only events in empirical chains, but even the "laws of nature" that govern the chains themselves. To put it metaphorically, the wills clash atemporally behind the curtain resulting in empirical world that plays out in time before each participating self, see Vilhauer's paper.

Kant came back to the problem in multiple subsequent later works, where he owned up to his argument as an actual theory, and kept changing and modifying it, sometimes substantially, never even to his own satisfaction. So does Kant's limited argument succeed on his own terms? Yes, but that is not saying much. Does he have a theory that is both palatable and consistent with his philosophy? By broad consensus, no.

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