Alexander Wendt's Quantum Mind and Social Science hypothesizes that all intentional phenomena, including both psychological and social facts, are macroscopic quantum mechanical processes. Whether right or wrong, the suggestion highlights the fact that the social sciences, including IR, have until very recently never systematically discussed the potential relevance to our work of the quantum revolution a century ago. According to Wendt, that has left social scientists today – positivists and interpretivists alike – operating from an implicit and impoverished 19th century worldview that cannot accommodate important facts about human subjectivity. This symposium features critiques of Wendt's vision from multiple perspectives and a response, for one of the first airings of the classical-quantum debate in an IR context.

This paper examines several aspects of Alexander Wendt's Quantum Mind and Social Science. The paper questions the nature of the task, as ontologies are debated in a scientific field once there is a widely accepted substantive theory that stands in need of interpretation, as with Newtonian physics or quantum mechanics; doing this job for international relations (IR) is highly questionable give that there is no widely accepted substantive theory of IR that needs an interpretation. Second, the paper questions Wendt's view of the consequences for ontology of quantum theory being replaced in the future; Wendt the interpretation of the history of science maintains that in the physical sciences a new theory subsumes the older theory, including its ontology. But, this seems to misread history, while the empirical content of classical physics is subsumed by relativity theory, it is far from true that the former's ontology was subsumed. The ontologies are in sharp contrast. The paper raises questions also about the notion of ‘truth’ and of the meaningfulness of evaluative concepts like ‘justice’.

This essay describes three commitments that have become central to the author's philosophical outlook, namely, to liberal naturalism, to metaphysical realism, and to the epistemic and ontological objectivity of normative judgments. Liberal naturalism is contrasted with familiar scientistic versions of naturalism and their project of forcing explanations in every field into models derived from one or another particular science. The form of metaphysical realism that the author endorses rejects every form of verificationism, including the author's one-time ‘internal realism’, and insists that our claims about the world are true or false and not just epistemically successful or unsuccessful and that the terms they contain typically refer to real entities. ‘Representationalism is no sin’. The central part of the essay is an account of truth based on a detailed analysis of Tarski's theory of truth and of the insights we can get from it as well as of the respects in which Tarski is misleading. (This part goes beyond what the author has previously published on the subject.) The account of the objectivity of the normative in this essay draws on insights from Dewey as well as Scanlon.