One of the most tangled problems in the long history of philosophy is the problem of the relation between experience and reason, a problem which appears in many guises: rationalism vs. empiricism, idealism vs. realism, the a priori vs. the a posteriori, and the analytic vs. the synthetic. Almost all the attempts to overcome the opposition between these two concepts have ended more or less in either surrendering reason to experience or experience to reason. The present work thematizes this age-old problem anew with particular reference to Hume"s "naturalism" and Kant"s "criticism". Both Hume and Kant claim to have given to philosophy a new and sure foundation.