Milum,

I don't know if Kant had much to say on existence; he had a lot to say about epistemology and ethics which, interestingly, he may actually have grounded in aesthetics.

As to Heidegger, what I understand of him has to do with his readings (explicit or impllicit) of Kant, but I really give *any* account of what he may or may not have to say about 'existence,' per se.

Maybe wsieber can be more helpful.

As to your suggestion that these two represent stages in human thought, alright, if you must. But give them a *little* credit, there is nothing about either of them to be so slighted as to suggest any Phd from Podunk could go them one better.