In his Critique of Pure Reason, Immanuel Kant wrote about the science of the transcendental aesthetic in which he argues that space and time exist as a priori intuitions in the human mind. Space and time, for Kant, are the pure forms of intuition that order our empirical intuitions or sensations and allow us to have them. Thus, the essence of his view in this regard is that space and time are subjective human conventions that our mind brings to the realm of experience. There is one argument of Kant’s for space being a pure intuition in particular that I find compelling.
Essentially, Kant says that empiricists advocate that the concepts of space and time are derived from our sense experience. Kant argues however, that it would be impossible for space and time to be concepts derived from sense experience because of the fact that all of our sensory experience is already ordered spatially. Kant poses that there exists, a noumena other than phenomena. Reality can either be the empirical/phenomenal world, or the non-empirical noumenal world, or they could be both.
The noumena may somehow house or emanate the manythat is in our minds in order to perceive empirical space and time. Kant points out that we can simultaneously view both the empirical reality of space as well as the transcendental ideality. As far as a whole or one whole, Kant posits that we cannot successfully conceive of the whole or entire entity of time, or space because it is supposed to be infinite as, in never-ending and formless.
I can show you the finite shape or form of an object, whether felt, heard, felt, tasted, or shown, but I cannot successfully show you the shape or form of either space or time itself, only the objects and events that reside within them. Kant points out that we dream, yet dreams are not empirically spatial. We can only say, I had a dream at such and such a time, yet we cannot go there, as in going to an actual physical place, so dreams are only temporal. Yet, dreams are still part of reality. The same applies for time and space.