Critically and comprehensively examining the works of Habermas and Foucault, two giants of 20th century continental philosophy, this book illuminates the effects of scientific reason as it migrates from its specialized institutions into society. It explores how science permeates shared human consciousness, to produce effects that ripple through the entire social body to restructure relations between discourses, institutions, and power in ways which we are barely conscious of. The book shows how science, through its entwinement with power, politics, discourses, and practices, presents certain social arrangements as natural and certain courses of action as beyond question. By arguing for a non-reductive, liberal scientific naturalism that sees science as one form of rationality amongst others, it opens possibilities for thought and action beyond scientific knowledge. The book analyses the work of Foucault and Habermas in terms of their social, political, and historical contexts. It examines science in relation to society, power, and discourses and their shifting historical relations. But rather than withdrawing from normative dimensions by merely describing scientific practices within their contexts, McIntyre explicitly opens the normative question of the good life and the good society. He thus simultaneously raises the question of philosophy and how philosophical critique is both directed towards science and, at the same time, must accommodate it. Foucault and Habermas emerge as linked by a commitment to the Enlightenment tradition and its emancipatory telos which underlies their work. The significant differences between the two thinkers are seen to result from Foucault’s radicalization of this tradition, a radicalization which is, at the same time, implicit within the Enlightenment project itself.