This chapter examines arguments for how political practices condition normative political principles. Such arguments have been made by practice-dependent theorists in the global justice debate and by political realists in the debate on political legitimacy. In the latter debate, realists argue that principles of political legitimacy must be theorised from ‘within’ the political, focusing on the actual institutions, practices and processes through which citizens address shared problems in their society. In the former debate, practice-dependent theorists argue that institutionally mediated relationships condition appropriate criteria of justice and that justice therefore must be theorised from the workings of actual institutions.

Even though there has been little or no exchange between these two debates, several premises are shared and would benefit from systematic scrutiny. This chapter presents and critically examines both arguments for political constraints on normative political principles. With regard to political realism, we demonstrate that the core question in the realist critique of political moralism concerns which justificatory domain ought to have primacy in deciding what political legitimacy is, and thus different forms of constraints on reasons in support of a principle of political legitimacy (e.g. political or moral reasons or both). It is argued that realists are wrong to claim that political moralism sees morality as something prior to or external to politics. Concerning the positive arguments put forward by realists, we argue that none of their justificatory strategies that allegedly put political constraints on normative political principles holds.

With regard to practice-dependent theorists focusing on political constraints in the form of institutions, a similar scepticism is raised against the primacy of institutions in deciding what justice is. The chapter analyses a weaker and a stronger interpretation of institutional practice-dependence. It is argued that the weaker interpretation is reasonable but does not imply that the choice between practice-dependence and practice-independence has wide-ranging implications for the content and justification of justice, as practice-dependent theorists claim. On the stronger interpretation, a de facto dichotomy between practice-dependence and practice-independence is established, but this is, we argue, at the price of being unreasonable.

WHAT IS SO SPECIAL ABOUT THE POLITICAL?

Political realism has become an influential approach in the current debate on political legitimacy and democracy. While it is fair to say that it is not yet a unified position, realists share enough assumptions to constitute an alternative approach to mainstream political theory.