J. Samuel Barkin and Laura Sjoberg are committed to making international relations as open a field of inquiry as possible. Their commitment is ethical but also practical as they argue—and I concur—that openness and tolerance promote more diverse and better research. Fields narrow for many reasons, and the one they focus on is the phenomenon of an intellectual “synthesis.” In theory, it is intended to transcend differences between approaches and encourage a “theoretical peace.” The authors argue that the attempted synthesis of neorealism and neoliberalism in the 1980s reduced richness and diversity by excluding, or at least penalizing, scholars who rejected or worked outside the synthesis. The same narrowing is happening again today, they contend, as a result of the more recent synthesis of constructivism and critical theory. Such syntheses, they argue, are intellectually questionable as well as negative in their implications. Barkin and Sjoberg acknowledge that constructivism and critical theory share some important characteristics but insist that they represent two different approaches to IR rather than components of a single theory.

To make their case, Barkin and Sjoberg devote two chapters to constructivism. They describe multiple forms of constructivism, many of which share ontological assumptions and methods. There are also important differences within each of these paradigms or research programs. Theories that qualify as constructivist, they argue, incorporate an ontology of co-constitution and intersubjectivity. Researchers rely on diverse methods for teasing out these relationships and how they affect international politics. Barkin and Sjoberg describe three kinds of constructivism: theories that build on norms, rules, and identities. In contrast to critical theory, Barkin and Sjoberg argue that constructivism does not embody a morality of politics. They might add that this absence also distinguishes constructivism from most forms of realism, liberalism, and Marxism. Constructivism, they note, can be associated with different political approaches, and they make the case for a “politically promiscuous” paradigm (p. 159).

Two following chapters make similar arguments about critical theory. There is much diversity among theories of IR that qualify as critical. They include those with explicit emancipatory goals, with many kinds of feminist theory, as well as with poststructuralist and postmodernist theories. These theories and approaches share a common ontology, belief that politics matters, and identify similar mechanisms by which politics is said to work. Efforts to build a synthesis of constructivist and critical theories involve a misreading of both research traditions and a rejection of their diversity in favor of one characterization. Such an effort “is intellectually bankrupt, normatively problematic, politically ineffective, and just plain wrong” (p. 17).

In their conclusion, Barkin and Sjoberg elaborate on their argument that efforts at synthesis are counterproductive to the dialogue they seek to foster. They maintain that constructivism need not be critical, and that critical theories need not be constructivist. However, the two kinds of theories can also be combined, but not in the form of a synthesis. Constructivism is a social theory that can be used as a method by critical theorists who are anchored in a political theory. Critical theories can also adopt constructivist social theories for their research. However, the important differences between constructivism and critical theory should not be ignored. Exploration of these differences and tensions, and foregrounding, not glossing over, them has the potential to promote a useful dialogue and richer and more diverse research programs.

I find the book’s argument compelling and on the whole well laid out and developed. In physics, syntheses work well, and progress in the field can be measured by its integration in the nineteenth century of electricity and magnetism, and in the postwar era, of both with the weak and strong forces. Only gravity remains outside the standard model and may someday be incorporated. Some physicists have raised concerns about the model but not about the idea of a synthesis that unifies all of nature’s forces. The social world, and international relations in particular, is different. We have no general laws to which phenomena can be subsumed, nor can we ever expect to develop them. It makes no sense for social science to ape physics. General theories are fine, but the idea of a general theory is impractical and dangerous. It dramatically distorts and narrows research in the process. We benefit from multiple theories in multiple traditions that respond to the intellectual and policy needs of the moment. As Barkin and Sjoberg recognize, comparisons and competition among them are beneficial to the field, especially when they highlight different assumptions and goals and their implications. These comparisons can also be useful when focused on the problems these different theories or approaches share, as most do, for example, in confronting data (see for example Richard Ned Lebow and Mark I. Lichbach, eds., Theory and Evidence in Comparative Politics and International Relations, 2017).

To the extent I have any differences with the authors, it is with respect to Barkin and Sjoberg’s single-minded focus on ontology as the principal conceptual basis for comparison of theories. This leads them to too expansive and too narrow a definition of constructivism. They identify co-constitution and intersubjectivity as defining ontological commitments of the paradigm. So-called thin constructivism of the sort advocated by Alexander Wendt does not really meet their definition yet they describe him as a constructivist. He ascribes identities to actors before they interact with others, and claims that they have strong incentives—even little choice—but to maintain the order they have created. Yet he also believes the liberal world order is inevitable (see Alexander Wendt, Social Theory of International Politics, 1999, pp. 326-36). By their criteria, Wendt is best characterized as a structural liberal.

Barkin and Sjoberg make no mention of my Cultural Theory of International Relations (2008), although it is to my knowledge the only general constructivist theory of IR. Perhaps they do not consider me a constructivist because I do not foreground co-constitution and intersubjectivity, although both feature in my theory. Instead, I build on human motives, the emphasis societies put on different motives, and how these motives are socially channeled. I theorize that the motives of appetite and thumos give rise to different principles of justice, generate different kinds of hierarchies, and have different implications for cooperation, conflict, and risk-taking. The emotion of fear can become dominant when reason loses control of appetites and thumos. It rests on no principle of justice and gives rise to its own kind of hierarchy and propensities for cooperation, conflict and risk-taking.

The explanation for this improper admission and exclusion from constructivism has to do, I believe, with the authors’ downplaying of epistemology. The concept gets considerable mention but is not at all central to their analysis and categorization of theories. They rely instead on ontology and political commitments, if any. Yet epistemology is critical to any scheme of classification. Even casual reference to it would reveal someone like Wendt as a positivist, in contrast to thick constructivists, all of whom to my knowledge are interpretivists. It would also characterize my work as unambiguously constructivist given its emphasis on reflexivity and the social nature of politics.

I want to be clear that I am not invoking epistemology or citing Wendt to exclude anyone. Rather, I want to show how the fit between a scholar and a paradigm very much depends on the criteria that are used for this purpose. Ironically, Barkin and Sjoberg, who wish to be inclusive, exclude me, and perhaps other self-avowed constructivists, by using the criteria that they do. They should acknowledge the sensitivity of their criteria, and the need, or at least the possibility, of using multiple criteria for categorization. Multiple criteria are another way of exploring relationships between and among research programs and theories. We can ask which fit together—or not—depending on the criteria chosen. This process can also be extended across research programs.

Through the lens of epistemology it becomes immediately apparent that most forms of constructivism are interpretivist. This is also true of critical theory, although not for many kinds of Marxism. In The Quest for Knowledge in International Relations (2022) I argue that the big divide in IR is between positivism and interpretivism, between those who believe in objective, cumulative knowledge and those who stress reflexivity and the subjective nature of knowledge. Epistemological differences are far more important than methodological ones; they generally determine the kind of method thought appropriate. Epistemology, like ontology, cuts across paradigms. We find positivist and interpretivist realists, liberals, Marxists, and constructivists—if we count thin constructivists among them.

Barkin and Sjoberg make an admirable case for diversity and tolerance and identify theoretical syntheses as a barrier to them. No doubt they are correct. However, syntheses are, I believe, a minor part of the problem. Every discipline contains people with authoritarian tendencies who wish to wield power. They use their personal status to exclude as far as possible those who do not conform to their ideology or acknowledge their authority. Their success rests with the control of journals, search and promotion committees, and funding agencies. We all know who these people are in IR and periodically read their indefensible—even risible—attacks on those who adopt a different approach to their research. The creation of syntheses is just one of the strategies they invoke in their search for control. This was particularly evident in the efforts to integrate neoliberalism with neorealism. It is somewhat less evident in the newer synthesis of constructivism and critical theory. Exclusion in this instance may be more of an unintended consequence.