The World 3 theory outlined by Popper in the 1960s has been diversely received, raising enthusiasms as well as severe criticisms. In this paper, I resituate the theory in the development of Popper’s philosophy. I not only present the three “sources” of W3, but I also show that the first one dominates the two others. Comparing it with a few other evolutionary philosophies, I propose to understand Popper’s metaphysics as part of an evolutionary and spiritualist philosophy, which was, however, always (...) balanced by a strong ethical reminder of the inescapability of human responsibility. (shrink)