This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. This book talks about the concept of progress, its separate varieties, its current rejection, and how it may be reconsidered, on a philosophical as much as a scientific basis. It not only distinguishes between the concepts of social progress and of scientific progress, but assumes their interconnection. By now, this linkage is well-understood through the medium of the culture: scientists work not only in laboratories, in seminar rooms, and in the field, but in the general ambience of their times, which include the spheres of literature, art, popular music, and philosophy. The book presents various examples of scientific progress, which, in effect, depart from Enlightenment history. "Historicism" denies that science makes progress, extending historical relativism to epistemological relativism; the social consequences are described in the concept of the "open society".