Appeals to practices are common the humanities and social sciences. They hold the potential to explain interesting or compelling similarities, insofar as similarities are distributed within a community or group. Why is it that people who fall under the same category, whether men, women, Americans, baseball players, Buddhists, feminists, white people, or others, have interesting similarities, such as similar beliefs, actions, thoughts, foibles, and failings? One attractive answer is that they engage in the same practices. They do the same things, (...) perhaps as a result of doing things at the same site or setting, or perhaps as a result of being raised in a similar way among members of the same group. In the humanities, appeals to practices often serve as a move to point out diversity among different communities or diversity within the same community. Communities are distinct from one another in part because their members do different things or do things in different ways. The distinct and varied ways in which different communities enact social norms or formulate law, state institutions, and public policy might be explicable in part by the different practices their members are socialized into. Appeals to practices hold the promise of explaining these differences in terms of the different background practices of the groups, cultivated through a kind of cultural isolation or sense of collective identity. In the social sciences, appeals to practices have played a central role in fundamental theorizing and theory building. Appeals to practices in the social sciences are often much more systematic and theoretical, forming the core of the systematic theories of Pierre Bourdieu and Anthony Giddens in Anthropology and Sociology. Practice theory has thus become a growth industry in social scientific investigation, offering the promise of a central object of investigation that explains both unity and difference within and across communities and groups. But it is unclear just what practices are and what role, both ontological and explanatory, that practices are supposed to play. The term `practices' is used to pick out a wide range of things, and its relation to other terms, from `tradition' or `paradigm' to `framework' or `presupposition', is unclear. Practices are posited as ubiquitous, yet they are difficult to isolate and pin down. We are all said to participate in them, but they remain hidden. Their role, whether causal, logical, or hermeneutical, remains mysterious. After locating the historical origins of appeals to practices in the work of Ludwig Wittgenstein and Martin Heidegger, my dissertation uses Stephen Turner's broad and systematic critique of appeals to practices to develop a new type of account. My account is a phenomenological account that treats practices as human doings that show up to people in material and social environments and make themselves available for specific responses in those environments. I argue that a phenomenological account is an effective alternative to accounts that treat practices as either shared objects with properties or shared and implicit presuppositions. I use a phenomenological account of practices to treat important debates in feminist philosophy and the philosophy of the social sciences, particularly debates over pornography's subordination of women and the classification of mental disorders in psychiatry. (shrink)