Full Idea
Kant deserves credit for showing that we have a priori knowledge which is not purely 'analytic', i.e. such that the opposite would be self-contradictory.
Gist of Idea
Kant showed that we have a priori knowledge which is not purely analytic
Source
report of Immanuel Kant (Critique of Pure Reason [1781]) by Bertrand Russell - Problems of Philosophy Ch. 8
Book Reference
Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.46
A Reaction
It is noteworthy that a great empiricist philosopher makes this judgement. But how do you spot an a priori truth, apart from seeing that its opposite would be a contradiction? Where else can its force come from?