Full Idea
We are all post-Kantians, ...because Kant set an agenda for philosophy that we are still working through.
Gist of Idea
We are all post-Kantians, because he set the current agenda for philosophy
Source
William D. Hart (The Evolution of Logic [2010], 2)
Book Reference
Hart,W.D.: 'The Evolution of Logic' [CUP 2010], p.31
A Reaction
Hart says that the main agenda is set by Kant's desire to defend the principle of sufficient reason against Hume's attack on causation. I would take it more generally to be the assessment of metaphysics, and of a priori knowledge.