Karl Popper (1902-1994), one of the most influential philosophers of the twentieth century, became a relevant philosophical figure as a result of his first epistemological reflections about physical-natural sciences. However, at present, the part of the thought of it that more interest raises, inside and outside the philosophical sphere is related to the considerations of it about the social sciences and the connection of it with issues of practical philosophy. This book is a good sample of it. In it, a legacy is submitted, the popperian, which is undoubtedly already a classic. Now, it is the contrast that a classic deserves: the one that enters critical dialogue with the thought of him from the concerns of contemporary philosophy. This is the point of view that the authors of this volume adopt, among which are prominent representatives of critical rationalism.