Book excerpt: When social scientists and social theorists turn to the work of philosophers for intellectual and practical authority, they typically assume that truth, reality, and meaning are to be found outside rather than within our conventional discursive practices. John G. Gunnell argues for conventional realism as a theory of social phenomena and an approach to the study of politics. Drawing on Wittgenstein’s critique of “mentalism” and traditional realism, Gunnell argues that everything we designate as “real” is rendered conventionally, which entails a rejection of the widely accepted distinction between what is natural and what is conventional. The terms “reality” and “world” have no meaning outside the contexts of specific claims and assumptions about what exists and how it behaves. And rather than a mysterious source and repository of prelinguistic meaning, the “mind” is simply our linguistic capacities. Taking readers through contemporary forms of mentalism and realism in both philosophy and American political science and theory, Gunnell also analyzes the philosophical challenges to these positions mounted by Wittgenstein and those who can be construed as his successors.