This is evident in other debates that have shaped International relation theory. The debate between realism and idealism was a reflection on the weaknesses of idealism after the First World War against the background of Hitler's expansion across Europe (see Carr 1946). Attempts to solidify the scientific status of realist IR were led by European émigrés to the USA, following the Second World War. The debate between behaviouralists and traditionalists pitted scholars in the USA, who wanted to make IR into a science, against the international society theorists of the English school (see Knorr and Rosenau 1969). The postpositivist debate in the late 1980s was a reaction against the dominant place of scientific method in the American context (see Lapid 1989). The dialogue over constructivism was a reaction to the third debate, or, as some prefer to call it the fourth debate (see Chapter 1), and an attempt to speak across the barricades it had constructed, while addressing problems raised by the end of the Cold War. The following develops various dimensions of the 'constructivist turn' (Checkel 1998) in IR. It begins with a general discussion of what it means to say that reality is socially constructed and then proceeds to a more in-depth discussion of related debates.