Two questions are the focal points of this investigation: Hume's problem of induction and Kant's question regarding the limits of scientific knowledge. Popper critically engages with apriorism and logical positivism. He also offers a critical assessment of conventionalism. The conclusion of the book is clear: there is no induction in the epistemological sense, and the boundaries of empirical science against all rationalist speculation based purely on reason can only be drawn using the criterion of falsifiability. What was found regarding the two fundamental problems of epistemology was first published in 1979. The third edition presented here has been supplemented with two new appendices, as well as many new notes and a foreword by the editor.