This book is based on the conviction that philosophy in the sense of an abstract, exclusively theoretical knowledge has ended its development and passed irretrievably into the world of the past. This conviction differs from the usual negative attitude toward philosophy, the systematic expression of which we find in so-called positivism. It differs from positivism because, in the first place, it refers both to the speculative current of philosophy, what positivists call metaphysics, and to the empirical current, i.e., to that which finds its ultimate and fullest expression in positivism itself. Secondly, this conviction of mine differs from the positivist one because, althought I recognize that the abstract-philosophical development has ended, I do not consider it fruitless. On the contrary, I recognize that it has led to certain positive results, the delineation of which is the principal task of this book. Thirdly, the self-satisfied certainty with which positivism draws, from the grou...