I actually like Kant's distinction between noumena and phenomena. But I have a nagging doubt.

If we look at modern physics, appearances can be explained by entities such as atoms, electrons and quarks which are not themselves picturable. I can't say that this reality is the noumenon because by Kant's definition the noumenon cannot be known.

But the approach of scientific rationalism may undermine the idea of the Ding an Sich. Maybe we don't need it. We just keep exploring. Kant had no knowledge of modern science.

Any help here would be much appreciated. I have searched Google in vain. Has anyone written on the matter?

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    I'm not sure if you're equating the noumena with the Ding an Sich, but if you are, be aware that not everyone agrees they are equivalent concepts. See 'Noumenon and the thing-in-itself' on This page. Aug 26 '21 at 13:40
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    Science deals with what we can perceive (empiric knowledge = empiric truth), not with the Ding-an-Sich. We don't have access to it, and reaching it is not the goal of science, it is impossible. "We don't need it": correct, we don't need it IN SCIENCE, because science deals only with experience. The Ding-an-Sich is, on the contrary, a key topic in philosophy (the mother of all sciences), specifically, it is essential in metaphysics.
    – RodolfoAP
    Aug 26 '21 at 14:02
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    @RodolfoAP: Saying 'we don't need ding an sich in science' is misleading. Science is modeling, which means there must be a 'thing' we model for the model to be meaningful. If I make a model of the Grand Canyon, that model ins't the Grand Canyon; if no such thing as the Grand Canyon exists — no ding an sich — that 'model' is at best a flight of fancy, without relation to science. Aug 26 '21 at 14:58
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    Please do not confuse the noumenal realm with Ding an sich. The latter is only a friendly reminder that what we represent as object of experience is formed by our cognitive faculties, ie. the human way of representing the object in question. Ding an sich was never intended to be understood as any kind of reality. To be precise, it is a contradictio in adjecto, see this answer of mine, under further evidence. The noumenal is real in Kant though.
    – Philip Klöcking
    Aug 26 '21 at 15:56
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    Well, do we need Kant at all? Scientific rationalism can probably get by without him. It is unclear what you are looking for. For the question to make sense you need to work from within Kantian perspective and find internal arguments for undermining Ding an Sich. An outside perspective does not undermine one piece in particular, it "undermines" the whole doctrine, if anything.
    – Conifold
    Aug 26 '21 at 20:03

"Kant had no knowledge of contemporary science" is I think a more accurate statement than "Kant had no knowledge of modern science," because "modern" science" generally refers to science since the scientific revolution of Newton and his approximate contemporaries in other fields of empirical inquiry. Kant's project was more "grounding" science than inventing something beyond the reach of science with the agenda of keeping philosophy above science (although a case can certainly be made for the latter). I don't think he considered his metaphysics a necessary and hitherto missing piece for the continuing progress of science; I think he considered it a pat on science's back.

But the lasting value of Kant's metaphysics is most evident in what future philosophers have developed off of it. The Ding-an-Sich concept isn't transformed by contemporary science; it's transformed by Hegel, who tries to demonstrate that it's not a thing that exists but a thing in us that defines our investigations of existing things (much like your sentiment that we just keep exploring and finding out more). I recommend Robert Brandom's reading of Kant and Hegel. And also Quine's "Two Dogmas of Empiricism" (that explodes Kantianism as much as anything does, at the analytic/synthetic distinction pivot-point of his theoretical edifice). (Rorty on Quine in Philosophy and the Mirror of Nature for a more readable and less technical rendering of the point.) But my overall point is just that there's a lot more to Kantian metaphysics than a surface reading of the phenomenal/noumenal distinction.

  • Good reply. I read Quine's Two Dogmas of Empiricism many years ago. As far as I remember he tried to demolish the analytic/synthetic distinction. I will get back to it, and also check out Hegel's view. I will even check out Rorty.
    – Marek
    Aug 30 '21 at 6:22
  • Rorty, no, no. He carries pragmatism to a ridiculous degree.
    – Marek
    Sep 6 '21 at 13:57
  • But. if we are investigating particles, would it make sense to say the there is a thing in itself behind the electron. According to much of contemporary physicists the electron is a purely relational entity.
    – Marek
    Sep 26 '21 at 13:00

The key to this problem is that the physical sciences produce models of the world; they do not access the world as such. When we talk about subatomic particles — proteins, electrons, neutrons, quarks, or what you will — we are applying concepts defined within a model that largely works to describe the events we see. We cannot see the particles directly, but we can see indirectly see effects on the world that we can attribute to these particles within this model, Therefore the particles are phenomena. In other words:

  • We assert that a table is an 'object' because we can place a cup on it, and the cup won't fall through to the floor (as opposed to, say, a hologram of a table). If we were to make a table out of a perfectly transparent material, we could still assert it was an object, because we could still place a cup on it without the cup falling to the floor. The cup not falling as a phenomenal experience that points to the existence of an object.
  • We assert that a quark is an 'object' because we can perform certain (highly technical) actions and produce consistent with the model that defined quarks. It doesn't matter that we can't 'see' them directly; like the transparent table, we see an effect that implies the existence of an object.

We don't really 'know' what's happening 'in reality' on the subatomic level. That's all noumena, beyond our grasp. We see certain phenomena; we build models that attempt to encapsulate that phenomena systematically; those models define arguable/argumentative objects that ostensible encapsulate meaningful elements of Ding an Sich. But there is always an insurmountable gap of knowledge between those modeled objects and Ding an Sich itself.

  • All current physical models are understood as approximate, but the goal of many physicists is a final, most fundamental "theory of everything" that would not be merely approximate in this way, at least as far as prediction is concerned. If we had such a theory, presumably it would still deal with purely mathematical properties of fundamental units (particles or strings or whatever), but would there be any good argument for thinking these units must have additional properties (metaphysical or otherwise) beyond those included in the theory?
    – Hypnosifl
    Sep 28 '21 at 15:32
  • @Hypnosifl: Physical models work because physical models whitewash irregularities under the error term. For instance, to 'truly' know the inertial moment of an object, we ought to know the composition and distribution of every single atom within that object: replace a carbon atom with a lead atom anywhere, and the inertial moment changes ever so slightly. But for most cases we can ignore such issues, modeling a point mass with uniform distributions and properties, because the results we get are within the error tolerances we set for ourselves. Sep 28 '21 at 15:45
  • @Hypnosifl: The more 'Grand' our Grand Theory gets, the more it becomes a whitewashed abstraction, divorced from the idiosyncratic details of the real world. Even if we get an exact understanding of how the fundamental forces interact with each other, we still have to apply it to practical uses, where the detail devils hold sway. As Ram Dass once said "I you think you're enlightened, go home a spend a weekend with your parents"; likewise, if you think you have perfect understanding, try putting it to use. Sep 28 '21 at 15:50
  • The fact that all models so far are approximations isn't a strong argument for the impossibility of an exact fundamental theory. Just as a hypothetical, imagine a world that does have such an exact mathematical rule underlying its behavior (like a cellular automaton), but where intelligent beings would need many centuries of technological development before they could get the necessary empirical evidence to demonstrate which fundamental theory is correct. Until then, wouldn't you expect all their models to be approximate, with error terms?
    – Hypnosifl
    Sep 28 '21 at 16:24
  • @Hypnosifl: You're missing the point. An exact model is still a model. If I had an exact map of the surface of the earth, it still wouldn't be the surface of the earth. It would tell me how to get to Chicago, but I'd still have to put feet on the ground to go there. Sep 28 '21 at 16:32

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