This book develops a critique of utopianism through a provocative comparison of the works of Karl Marx and F. A. Hayek, thus engaging two vastly different traditions in critical dialogue. By emphasizing the methodological and substantive similarities between Marxian and Hayekian perspectives, it challenges each tradition's most precious assumptions about the other. Through this comparative analysis, the book articulates the crucial distinctions between utopian and radical theorizing. Sciabarra examines the dialectical method of social inquiry common to both Marxian and Hayekian thought and argues that both Marx and Hayek rejected utopian theorizing because it internalizes an abstract, ahistorical, exaggerated sense of human possibility. The chief disagreement between Marx and Hayek, he shows, is not political but epistemological, reflecting their differing assumptions about the limits of reason.