Social science has developed on the premises of social and scientific optimism and as the intellectual pendant of a liberal ideology which sought to manage change and claimed to be able to eliminate the sources of social unhappiness. Modernity has been justified on the materialist and collectivist bases of the amelioration of the conditions of life and of social justice for all. But these have proved to be unfulfillable promises which are no longer trusted. Furthermore, capital accumulation is incompatible with this legitimation of modernity because it is based on the appropriation of surplus value by some from others. How can social science and social scientists respond to the present era of pessimism in which the limits of the liberal and capitalist agendas have been recognized? Social science must recreate itself: the key element is the return of substantive rationality to the centre of our intellectual concerns. Science is never disinterested and empiricism always presumes prior commitments. The ambiguity of Weber's distinction between formal and substantive rationality is built into the modern world's geoculture. Substantive rationality involves the choice of a moral politics which addresses the issues of collective welfare and freedom from subordination to a formal rationality masking a substantive irrationality. The role of the intellectual class is to illumine our common, collective, choices.