In The Quest for Knowledge in International Relations, Richard Ned Lebow addresses the question of what counts as good theory in IR by focusing on the epistemological foundations of the discipline. He does this by constructing a binary distinction between positivism and interpretivism, looking at their different—and in ways opposite—assumptions about how knowledge is claimed and acquired. The book is a wide-ranging trip through the history both of IR as an academic discipline and of twentieth-century debates about the philosophy of science and social science. Its ultimate conclusion is twofold. First, that interpretivism, understood in a more or less Weberian way, provides a better basis for knowledge in the social sciences generally, and IR specifically, than positivism, although practitioners of both could learn from each other. And second, that IR scholarship should be thought of as an ethical practice rather than a search for epistemological warrants for truth claims.

The arguments supporting this conclusion are structured around the four sections of the book. In the first Lebow introduces the discussion of positivism and interpretivism in the context of a broader discussion of what knowledge is in the social sciences, drawing largely on the Vienna Circle for positivism and Weber for interpretivism. The second reviews a set of specific methodologies used in IR scholarship, ranging from correlational research to rationalism to practice theory, as examples of his two epistemological categories. The third addresses two specific grounds of epistemological difference between the two categories, that between verification and falsification of theory and that between causal and non-causal narratives. The fourth looks at the role of reason, cause, and mechanisms in IR theory.

The book fits into a broader literature, both in IR specifically and in the social sciences more generally, of dichotomizing scholarship into two categories, one involving quantitative methods and an affinity for the natural sciences (or at minimum with what social scientists imagine the natural sciences to be) and the other involving qualitative methods and an affinity for the humanities and history (e.g., Andrew Abbott, Chaos of Disciplines, 2001). In IR this literature can be traced back to the second “great debate” in the discipline’s telling of its history, between science and history. Lebow’s addition to this literature is to ground the dichotomy more explicitly in questions of epistemology and in more recent metatheoretical debates in the field. This grounding, however, begs the question of whether the dichotomy presents a productive framing of questions of epistemology in IR. Lebow notes (on p. 24) that by subsuming all non-positivist approaches under the banner of interpretivism he is “likely to annoy representatives of these approaches” for not addressing the specifics of their positions. He goes on to quote a reviewer of the project at manuscript stage as saying that “only to a neopositivist would ‘interpretivism’ appear to be anything like a coherent category.” But Lebow, in what is the key gambit of the book, stakes out the position that it is coherent.

Lebow’s arguments about the need to separate questions of method from questions of epistemology and to think of causes in IR in broader ways are well taken. At the same time, there are two categories of reasons that reifying a positivist/interpretivist distinction may not be the best way forward in encouraging both thinking and communication within the discipline about questions of epistemology. The first is that it is not clear, even from a Weberian perspective, that the dichotomy is able to carry the explanatory weight that Lebow wants it to, because too much of the research published in the discipline does not fit neatly into it. The second is that dichotomies both reify categories and exclude those that do not fit into them, and this process of exclusion strikes me as problematic. The remainder of this review fleshes out these claims.

Beginning with the concern about reification, Lebow claims at the outset to be talking about positivism and interpretivism as epistemologies, and at various points in the book he grounds his discussions of them in intellectual histories drawing on the works of scholars such as Karl Popper and Max Weber. But when making the transition to discussions of IR theory the connection with epistemology per se becomes attenuated in places. At some points in the book he seems to be discussing the dichotomy as one of methodology, at others as one of disciplinary sociology. Positivism then becomes a description of a group of scholars who use numbers and gatekeep aggressively rather than a description of a type of knowledge claim that they supposedly make. He also introduces as definitional aspects of positivism elements that are difficult to substantiate either in intellectual history or in current IR scholarship, such as the idea that positivist theorizing is necessarily top-down and interpretivist bottom-up.

In fact, at times positivism ends up sounding less like a clear epistemological stance than a list of research programs Lebow doesn’t like. Two examples can be found with Waltzian neorealism and rational choice theory, both of which he categorizes as positivist. Lebow associates positivism with, among other things, empiricism and reductionism. Waltz makes a structural-functionalist argument against reductionism in the development of a theory that he claims is not testable. It is not clear how these contradictions can be reconciled in a way that makes Waltz an epistemological positivist, even though he is often associated with the science side of IR’s second debate.

Similarly, Lebow incudes rational choice theory in the category of epistemologically positivist approaches to IR, and argues at significant length that it is not a useful approach to IR. But the argument is undermined in two ways. First, he does not make clear in what way rational choice theory is positivist. Practitioners generally interpret rational choice assumptions as “as-if” statements (in which case they are Weberian ideal types), or as claims about human nature that are ontologically prior to observational evidence (in which case they are philosophically realist claims). Neither fits into Lebow’s definition of positivism. Furthermore, much of his critique of rational choice theory is normative (it leads to bad outcomes and legitimizes neoliberalism) and empirical, rather than epistemological. With both rational choice theory and Waltzian neorealism the association with positivism seems much more about disciplinary sociology and arguments about who is a legitimate social scientist than about epistemology per se.

Which links with the second category of reason that a positivist/interpretivist dichotomy is not clearly a more useful way to conceptualize epistemology in IR than a more nuanced categorization. It encourages people to take disciplinary sides and raises questions about who is left within the boundaries of legitimate social science and who is excluded. Lebow tries to finesse this issue in the conclusion of the book by calling for better communication across epistemologies and for finding some methodological common ground between them. But it remains unclear what the philosophical basis can be for common ground between two mutually incompatible sets of arguments about what counts as a legitimate knowledge claim in IR.

The dichotomy, by suggesting that there are only two sets of legitimate epistemological claims upon which to base theorizing and research in IR, effectively excludes work that is not rooted in either of those claims (e.g., J. Ann Tickner, “What Is Your Research Program,” International Studies Quarterly 49[1], 2005). Lebow in fact explicitly states that some kinds of critical theory do not fit into his interpretivist category, although he does not make clear either where the line is between included and excluded or, in any real detail, what the logic of exclusion is. In a sense, he is using the concept of interpretivism as an exercise in disciplinary gatekeeping in a way analogous to how Gary King, Robert Keohane, and Sidney Verba (Designing Social Inquiry, 1994) use positivism. This is in contrast to the way someone like Patrick Thaddeus Jackson (The Conduct of Inquiry in International Relations, 2011) uses epistemological categorization, to understand and enable rather than to exclude.

Lebow’s argument for where the new boundaries of IR should be may resonate with committed Weberians but is less likely to be convincing for readers coming from other epistemological starting points. His argument also ends up suggesting that interpretive questions (e.g., how did outcome x come to be) are better or more appropriate questions in IR than inferential questions (e.g., what are the general effects of x on y), illustrated primarily with discussions about the causes of war. But ideally epistemology should be helping us to think about how to answer questions we have about the social world rather than telling us what kinds of questions we should not be asking. Whether one agrees or disagrees with the conclusions, though, The Quest for Knowledge provides a broad and historically informed overview of a debate that has been going on in IR for over half a century and that shows no sign of going away. It raises key issues in how we think about social science epistemology and, perhaps even more importantly, forces readers to reflect on the epistemological starting points of their research.