This was a dead-end in the history of Western thought. We started an irrelevant definition of knowledge (Cartesian Rationalism where geometry is the paragon of knowing) and arrived at equally irrelevant conclusions about metaphysics (Cartesian Dualism which eventual collapsed into Spinozaist monism (Hegel is correct in his assessment of Leibniz on this point)). Kant is trying to solve a set of non-problems with a highly innovative method that offers some seriously questionable solutions when you really get deep into German Idealism. The simply reality is that our knowledge and methods of understanding the physical world is more robust than the Rationalists would acknowledge, and our knowledge of our metal world is far more tenuous than we would care to accept. We really don't have access to as much of our minds as we intuitively think we do. The unravelling of this theory starts with Freud but modern psychology and neuroscience present a huge number of examples where it is very clear that we do not have direct access to the thing we call a unified consciousness or the self. The isn't about physics answering the question as much as the fact that the origin of mind and thinking will have a physical origin. Reductivism is equally played. Trying to reduce this process down to bits and atoms is probably not helpful or interesting. But it is really a moot point as to whether an emergent phenomenon is an ontologically separate thing from it's substrate. It is physical nonetheless in more or less the same way that we would think of the more basic entities. A form of soft-immaterialism might be secured in trying to ascribe existence to this emergent state of matter, but given what we know about people's ability to introspect their own consciousness I doubt that the traditional concept of 'soul' handed down to us from the Scholastic tradition can really be salvaged.