This chapter presents some conjectures as to how Hume might have criticized certain central epistemological doctrines of Kant. There can be little doubt that one of the main purposes of Kant's theory of knowledge was to overcome Hume's skepticism, and to establish the apodictic validity of a number of basic principles of factual knowledge. Hume would certainly not have allowed Kant to escape between the horns of this dilemma by declaring the constancy assumption itself to be synthetic a priori, for in that case Kant would be faced with an infinite regress in transcendental deductions. It may well be granted that this is the current common understanding of the significance of the term ''scientific knowledge." It certainly was also Kant's understanding. In his brilliant and powerful analysis of scientific knowledge Popper has emphasized again and again that there can be no justification of inductive inference.