From Asher Moore’s “Existentialism and the Tradition”:
In Kant’s synthesis, transcendence was prior, existence derivative. There is one place in his thought, however, at which it looks like he might reverse this order. This is the concluding section of the Dialectic. Leibniz’ pretensions to knowledge of self, other selves, and God have just been disposed of. We have not yet been told, except in asides, that those realities are still there, busy changing into their second-act costumes. Here on this watershed, and for just a moment, there is a sense that God, self and other selves are indeed present, but present as absent, as ideals and lures, as almost empty memories.
If one were determined to find nothing new in existentialism, to hold it derivative through and through, I think one would derive it, not really from Hume–who, except to the eyes of fondest affection, is too one-sided–but from this particular moment in Kant–this moment when, in Kant’s imagination, Hume stands alone on the battlefield, the unchallenged victor, but suddenly and poignantly moved by the grandeurs he has struck down. For existentialists, transcendence, the ontological dimension, is present, but taken in its own inner sense, per se, it is present as an ideal, a standard of comparison–something regretted or hoped for, heard or plighted–a brave, comic pretension.