Why be robust?

How can liberal political theorists combine their normative commitments with realistic assumptions of human behaviour and capacities? This is an important question for scholars who wish to use their theories to evaluate existing political institutions and recommend practical alternatives. This chapter describes a particular approach to realism in political theory by using the notion of 'robustness' from the Robust Political Economy framework. Robust institutions are those that perform well even when people are neither omniscient nor perfectly motivated to follow the common good. I argue that these problems, of limited knowledge and self-interest, emerge from three assumptions about the constitution of human beings commonly found in the liberal theoretical tradition: methodological individualism, subjectivism and analytical egalitarianism. I propose a combination of public choice and market process theory as best suited to the task of evaluating the robustness of normative political theories because they allow us to apply these assumptions systematically to all domains of human activity. Compared to standard neo-classical methodology, this approach offers an enriched account of the epistemic challenge to social co-operation that individuals face and the role of institutions, including private property and voluntary exchange, in ameliorating this challenge. I show how this systematic evaluation of the motivational and epistemic properties of institutions can help critique and extend RawlsÕ contractarian theory of justice and offer a new perspective on the role of realism in political theory.