[i] t is probably most useful to describe constructivism as based on a social ontology which insists that human agents do not exist independently from their social environment and its collectively shared systems of meanings (‘culture’ in a broad sense). This is in contrast to the methodological individualism of rational choice according to which ‘ [t] he elementary unit of social life is the individual human action’. The fundamental insight of the agency-structure debate, which lies at the heart of many social constructivist works, is not only that structures and agents are mutually co-determined. The crucial point is that constructivists insist on the constitutiveness of (social) structures and agents. The social environment in which we find ourselves, ‘constitutes’ who we are, our identities as social beings. (references removed) For constructivists, institutions are understood broadly to include not only formal rules but also informal norms, and these rules and norms are expected to ‘constitute’ actors, i. e. to shape their identities and their preferences. Actor preferences, therefore, are not exogenously given and fixed, as in rationalist models, but endogenous to institutions, and individuals’ identities shaped and re-shaped by their social environment. Taking this argument to its logical conclusion, constructivists generally reject the rationalist conception of actors as utility-maximizers operating according to a ‘logic of consequentiality’, in favour of March and Olsen’s (1989: 160-2) conception of a ‘logic of appropriateness’. In this view, actors confronting a given situation do not consult a fixed set of preferences and calculate their actions in order to maximize their expected utility, but look to socially constructed roles and institutional rules and ask what sort of behaviour is appropriate in that situation. Constructivism, therefore, offers a fundamentally different view of human agency from rational-choice approaches, and it suggests that institutions influence individual identities, preferences, and behaviour in more profound ways than those hypothesized by rational-choice theorists.
A growing number of scholars has argued that EU institutions shape not only the behaviour, but also the preferences and identities of individuals and member governments (Sandholtz 1993; Jшrgensen 1997; Lewis 1998).