Clarifying Example

"What Copernicus did was take the existing a priori concept of the world, the notion that it was flat and fixed in space, and pose an alternative a p riori concept of the world, that it's spherical and moves around the sun; and showed that both of the a priori concepts fitted the existing sensory data."

The above excerpt comes from Kant's Critique of Pure Reason, which I found in Zen and the Art of Motorcylce Maintenance (I did not read Critique of Pure Reason along with our current, beefy assignment). I remembered coming across Hume and Kant in Zen and Art of Motorcycle Maintenance and wanted to review what the author, Robert Pirsig, had said about them. I, like a few others (I believe) in class on Monday, was having trouble interpreting what exactly Kant was claiming about human understanding and how it differed, if at all, from Hume's Enquiry.

Copernicus' method of forming the Copernican Revolution was a clarifying example for me, and I wish to share it here in hopes that other confused Kantian readers find clarification as well. Copernicus, as Kant states above, changed our internal understanding of the world from an unmoving, flat object to an orbiting, spherical object. Space and time constituted both understandings, and the spacial and temporal representation of a flat world fixed in our minds properly assimilated the flux of sensory data we experienced just as well as the spacial and temporal representation of a round world.

But Copernicus used the mind's intuitive faculties of perceiving things in space and time to amend our understanding to the one accepted today. Upon viewing a moon revolving around Jupiter through his telescope, he used intuitive faculties to form the concept of a round earth revolving around the sun. How could he have come to this assured truth, one he believed to be as true as we know it today, based solely on experience? He never experienced a round earth in one complete vision, considering humans were far from the ability to view the earth in third person from outer space. Even if he could sit afar and perceive the earth's shape, it would be hard to patiently watch it revolve around the sun for a year. The reasoning behind the Copernican Revolution was not an a posteriori synthetic judgment, but an a prior synthetic judgment. He spatially built the true image of the world and temporally revolved it around the sun, all in his mind. Brilliant!