Science is perhaps most interesting as a kind of social movement. We begin by considering four common understandings of science, and then define a fifth, by contrast.

1. Science as a style of reasoning that pervades just about everything in the modern era. It is epitomized in Max Weber's process of “rationalization”: the inexorable replacement of local folkways and traditions with formal administration. While this conception correctly stresses science's historical tendency towards global colonization, it obscures the uneven and reversible ways in which scientific styles of reasoning have become implicated in social processes.

2. Science as common sense rendered self-conscious, which, over the course of evolution, has enabled human beings to flourish in an ever wider variety of environments. This view is associated with the American pragmatists, especially John Dewey. While correctly stressing science's aim at controlling – and, indeed, remaking – the natural environment, it overestimates the naturalness of this way of being in the world (to the point of rendering it “biological”) and hence obscures the historical contingency of our world happening to become (and remain) a scientific one. From this perspective, positivistic vigilance in policing the precincts of science begins to make sense, regardless of the acceptability of specific positivist strategies for demarcating science from non-science.

3. Science as the content of scientific beliefs, which today spread faster than any other kind, often enjoying the authority previously reserved for religious beliefs.