This paper raises the issue of what it is to be "critical" in education studies and in social theory more generally. It argues that this idea has for a long time been associated with forms of social constructionism and sociological reductionism. These understand the idea that knowledge is social in terms of reducing it to the experiences and interests of the groups whose perspective knowledge is held to represent. In this way knowledge is conflated with knowing. This approach has the consistent problem of collapsing into a relativism that denies of possibility of objectivity in knowledge or an epistemologically independent basis for knowledge claims. This paper offers an alternative view based in critical realism that attempts to provide non-relativist, though fallible, grounds for knowledge claims that restore a sense of autonomy to fields of knowledge production by understanding the sociality of knowledge in terms of emergent materialism. In this manner, the argument provides an alternative to both social constructionism and to Bourdieu's relationalism. (Contains 6 notes.)