Pure concepts which are recognized by Kant for their epistemological functions may themselves serve an argument for immateriality of the soul. The argument can look like this

Pure concepts don't contain any particular material property.

That which doesn't contain material property must be immaterial.

Mind thinks and contains these immaterial entities.

That which thinks and contains immaterial entities must itself be immaterial.

Therefore mind is immaterial.

I am interested to know whether such an argument was ever addressed by Kant, not that how he might have responded to it. Was this argument ever on the debate at his time?

  • 1
    Kant addresses it in the Second Paralogism when criticizing "rational psychology". The second premise/inference is either irrelevant or fallacious because it conflates properties of appearances with those of things in themselves. It matters little whether pure concepts "contain" material properties, the question is whether they can appear on the basis of something material. As the basis is unknowable to us, we can draw no inferences either way, see Kitcher's discussion, p.201ff.
    – Conifold
    Nov 20, 2023 at 6:02
  • @Conifold, Alright. That's just an extension of the same argument from agnosticism about a postulated noumena, which is itself problematic for several reasons including because categories of reality and causation have to apply to noumena to make sense. Kant on occasions admits argument for immateriality of soul but immediately counters its significance by pointing to its additional implication for immateriality of external noumena, which is however unproblematic on a panpsychist account according to which all phenomena are at bottom conscious.
    – infatuated
    Nov 20, 2023 at 8:11
  • There is no need for Kant's global agnosticism, the main problem of this argument is parity. We know very well how "immaterial" things like shapes come out of "material" properties even at the level of appearances. If they do it there why not here? We are not even entitled to far-reaching surmises about "pure concepts" as such, all we have are material beings talking about or thinking them. That much is pretty material. But let's say there is some X we do not know how to represent as a manifestation of matter. So what? Arguments from ignorance are not very compelling.
    – Conifold
    Nov 20, 2023 at 8:34
  • @Conifold I'm wondering how shapes or any other abstraction can come out of matter without the abstracting power of mind. That's unlike anything happening in the "material" world. The idea that such a new and peculiar power can arise from something without that power seems contradictory. I mean things lacking a property giving rise to something having that property. It's there in pure shapes and it is there in pure concepts.
    – infatuated
    Nov 20, 2023 at 15:42
  • It may seem unfamiliar or surprising at best, not contradictory, and not even that in many cases. Any set has properties its elements lack, and that's just a bare set, gases have temperatures, pressures, etc., none of which are properties of their particles. This kind of abstraction does not require "powers of mind" either, just disregarding some material features in favor of others, which any sensor or detector does. Computers identify shapes in images without a mind too. These kinds of arguments are basically circular, they insert their conclusions into interpretation of their premises.
    – Conifold
    Nov 20, 2023 at 19:24

1 Answer 1


Depending on how you read Kant's level of confidence in the existence of a pure will, you might find that Kant's discussion of the spontaneity of understanding but especially of reason resonates with your question. For example, at one point (in the second Critique) Kant says that the moral law announces itself as a synthetic a priori fact of reason, yet without a grounding in intuition. The synthesis is effected, so to speak, in the pure will itself, by some kind of will-to-synthesis (this is my best attempt to interpret what Kant says, here, anyway!).

So since the pure conception of the pure will is generated on the theoretical side in the context of the third antinomy, and on the practical side it is the sine qua non of the whole system of practical representation, one might take the key representation as disclosing our noumenal aspect thus far. But the "axiom" of the system is then moral (but so see about the primacy of pure practical over pure theoretical reason), and is "eventually" admixed with those empirical elements required for us to make sense of our physically-situated responsibilities. We can postulate immortality of some form in light of this a priori synthesis of the will, but this won't be the same as a metaphysical proof that the soul of the will is immaterial (the question as such is not technically decidable for the sake of resolute belief, but only moral hope (see O'Neill[96] for an extended discussion of this fine point of contention).

  • so what is the content of that hope; that this is me, that i am more than this; that this isn't me?
    – user67675
    Nov 20, 2023 at 14:58
  • 1
    @prof_ghost it's up to us. If we are minded to be theists about our hope, then we may (not must) hope that what we are is something that God can help on the way to perfect virtue. If we are not theistically-minded, we may hope that the ramifications of our physical actions, on the course of history, can be such as to improve that history. In one context, there is a communitarianism for the self-and-God, the other a communitarianism for various-phenomenal-selves, I suppose. (We are not, or are not meant to be, moral islands!) Nov 20, 2023 at 15:00
  • that's a great comment, thanks
    – user67675
    Nov 20, 2023 at 15:03

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