In 1990, the neoliberal institutionalist Robert Keohane defined multlateralism as “the practice of co-ordinating national policies in groups of three or more states, through ad hoc arrangements or by means of institutions” (Keohane, 1990, p. 731). In common usage, multilateralism refers indeed to cooperative arrangements among multiple states indeed. Hence, the UN or World Trade Organization are ‘multilateral intergovernmental organizations.’ For collaboration among smaller groups of 3 or a bit more states, the term ‘minilateralism’ is sometimes used.
However, the more constructivist-inspired scholar John Ruggie looked for a richer, more qualitative definition, since “what is distinctive about multilateralism is not merely that it coordinates national policies in groups of three or more states, which is something that other organizational forms also do, but that it does so on the basis of certain principles of ordering relations among those states.” Hence he posits: “At its core, multilateralism refers to coordinating relations among three or more states in accordance with certain principles” (Ruggie, 1992, pp. 567-568).
Further elaborating he defines “multilateralism [as] an institutional form which coordinates relations among three or more states on the basis of ‘generalized’ principles of conduct – that is, principles which specify appropriate conduct for a class of actions, without regard to the particularistic interests of the parties or the strategic exigencies that may exist in any specific occurrence” (Ruggie, 1992, p. 571).
Building on this principled dimension, ‘multilateralism’ also denotes states’ or policy-makers’ ideological preference for multilateral responses to international and transnational societal problems. It contrasts with ‘unilateralism’, which implies state action in the world without coordination or consultation with the rest of the international community. Multilateralism also differs from isolationism, which includes a government’s inclination to detach itself from international collaboration and commitments.