This book traces the rise and fall of political philosophies since the 17^th century. The second part of the book shows how the general technique of cumulative learning from experience applies to social legislation and social services, party politics to defence strategy and to the trends that follow the modern explosion of knowledge and capital. The main argument is that social control is at its best a deliberate joint creation of and learning from social experience; and in this sense political discipline although not the same as logical or scientific discipline is like them a submission to form, not force. The book gives a definite meaning to the idea of human progress and finds reason for a restoration of political hope and faith.