The interpretation placed on terms such as 'social justice' and 'social rationality' in urban planning has undergone a powerful evolution over the last 20 years. This transformation in meaning parallels the shift from modernist to postmodernist ways of thinking about cities and about the possibility of engaging in interventionist planning practices. Examination of resistance to the construction of Baltimore's highway system in the 1960s suggests, however, that supposedly modernist and universal conceptions of social rationality and social justice were always highly contested and that this contestation presaged the turn to more explicitly heterogenous postmodern views. But the underlying power relations have not changed, though they have become much more open and direct through privatization and the articulation of a strong free-market ideology which presumes that the market always generates socially just outcomes. To the extent that the latter is manifestly untrue, the development of an alternative vision of social justice, which accepts variation of meaning across time, space and individuals, can become a powerful mobilizing rhetoric for alternative forms of political action in urban settings. The contemporary problem is therefore, to confront the negative consequences of dominant power relations and market mechanisms by an appeal to notions of social justice which preclude any return to earlier and largely discredited practices of bureaucratic rationality and state paternalism.
