The argument echos Kant...which is too big a sea to boil in a comment. So at geostationary orbit, Kant's metaphysics says we cannot have absolute knowledge of the empirical world, only knowledge mediated by the a priori conditions of human experience, space and time. However, we can have absolute knowledge of morals because such knowledge is not dependent on the aforementioned a priori conditions of human experience.

Going further, in Critique of Pure Reason Kant uses mathematics as an example of synthetic a priori knowledge. This is the lever he uses to overturn the traditional halving of all knowledge into either analytic and a priori or synthetic and a posteriori (empirical). The halving was the basis for Hume's radical skepticism and it's predecessors.