In the literature, the power debate is divided between modern and postmodern positions. The former hold that power and truth are opposites, while the latter view them as mutually constitutive. These debates mix epistemological, normative and sociological claims. Using classical sociological methods, strict criteria for valid functional explanations are set out and the relationship between power and truth is explained in these terms. It is argued that agents use truth to create local social capital for themselves, which has the unintended functional effect of reinforcing the effectiveness and stability of social systems. This entails an account of authority as a performative act that meets with a felicitous reaction by others.