Full Idea
Since philosophy is merely rational cognition in accordance with concepts, no principle is to be encountered in it that deserves the name of axiom.
Gist of Idea
Philosophy has no axioms, as it is just rational cognition of concepts
Source
Immanuel Kant (Critique of Pure Reason [1781], B760/A732)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.640
A Reaction
This is an attack on traditional rationalism, which aspires to do philosophy in the style of Euclid. Kant offers, however, a very conservative view, in which all concepts are 'given'. Nowadays we want to play with new axioms, as they did in geometry.