What is the structure of the universe?
The question presses exactly on the weak nerve of Kant, if all known structure is structured-through-us, then how can we speak about the structure of the universe beyond us?
His answer is that we cannot, at least not as knowledge. We can think it. We can postulate it. We can use it as a limiting idea. But we cannot know it in the strict sense, because knowledge requires the very cognitive conditions whose universality beyond the human standpoint cannot be established.
That is the price of Kant’s revolution. He saves objective knowledge within experience, but he blocks metaphysical access to reality in itself. Now let us strip the illusion further. There are really only three options here.
The first option is naïve realism, the structure we perceive just is the structure of reality itself. Kant says this is unjustified, because we only ever access reality through cognition.
The second option is naïve realism, reality is basically mind-made. Kant does not want that either, because he insists that something independent of us affects sensibility.
The third option is transcendental idealism, the form of experienced reality comes from the joint operation of an external source plus the structuring activity of the mind. This is Kant’s position.
So if you ask, “How do we know the structure of the universe?” the Kantian answer is that what we only know only the structure of the universe as experienceable by beings like us. That is both modest and devastating. It is modest because it limits human arrogance. It is devastating because it means metaphysics cannot honestly claim final access to reality.
A modern way to put it is this is that the human mind may be less like a camera and more like a formatting engine. If so, what we call “the world” is already world-for-a-human-knower. And here is the sting, you cannot step outside the apparatus to compare the formatted output with the original file. There is no neutral viewing platform. The wish for one is just reason fantasizing about its own escape hatch.
This is also why later thinkers either tried to overcome Kant or radicalize him. Schopenhauer accepts the barrier but thinks the will gives one special clue to reality from within. Nietzsche treats the demand for access to things-in-themselves as another ascetic craving for a pure world behind appearances. Metzinger would put pressure on the transparency of the self-model and show that even the subject who claims to know is part of the constructed interface. Different moves, same wound.
So the rigorous answer is, we do not know the structure of the universe in itself; we know the lawful structure of phenomena. That is the only universe available to cognition without myth. What human beings often call “knowledge of reality” is usually knowledge of the stable format in which their nervous system is forced to receive reality.
