ANT is based on no stable theory of the actor; in other words, it assumes the radical indeterminacy of the actor. For example, neither the actor's size nor its psychological make-up nor the motivations behind its actions are predetermined. In this respect ANT is a break from the more orthodox currents of social science. This hypothesis (which Brown and Lee equate to political ultra-liberalism) has, as we well know, opened the social sciences to non-humans.