The astonishing success of the natural sciences in the modern era has led many thinkers to assume that similar feats of knowledge and power should be achievable in human affairs. That assumption, and the accompanying notion that the methods of modern science ought to be applied to social and political questions, have been at the heart of a number of prominent philosophical schools in the modern age, and much of the politics of the past century. Is the application of scientific logic to the study of human affairs philosophically defensible? Does it aid or hinder our efforts at a genuine understanding of the human world? Why have so many modern ideologies, including those responsible for some of the greatest atrocities of the 20th century, advanced themselves under the banner of science? Why, in other words, do we assume that modern science holds the key to an understanding of human affairs? Are we right to make this assumption? And what does the assumption mean for contemporary society and politics? Tyranny of Reason, which is designed for the interested lay reader and for undergraduate or beginning graduate students in the social sciences, attempts to answer these important questions in the context of the history of philosophy.