Realism is the best theory of International Relations because it continues to provide the discipline’s fundamental ontology, is its most progressive programme, and is the most convincing problem-solving account of emergency politics. Since different traditions disagree on what counts as a test, and metrics are themselves theory-laden (Kuhn 1962; Jackson 2011), this essay analyses realism against three different conceptions of what defines a goodInternational Relations theory – its paradigm, research programme, and capacity for problem-solving. This essay defines realism as a ‘research programme’ with a hard core of commitments, and a protective belt of revisable auxiliary theories and assumptions (Lakatos, 1978; Donnelly, 2000). Though different sub-sects of realism offer different expansions of its fundamental concepts and propositions, realism is defined by a commitment to international relations as characterised by the power-maximising actions of states in an inherently anarchicsystem (Donnelly, 2000).
Firstly, realism is the best theory of International Relations because it provides the discipline’s foundational ontology. As Wight argues, ‘all theories presuppose a basic ontology from which all other considerations follow. No ontology, no theory’ (Wight, 2006). The discipline’s deepest disagreements are about what exists: competing theories constitute different worlds rather than merely explaining the same world differently. The question is therefore which theory’s account of what IR is proves most durable and generative. Crucially, Wight also establishes that every theory must presuppose some account of what exists; the only choice is between competing ontologies (Wight, 2006). Under this conception of how theories should be compared, realism’s account is the most defensible. Realism’s ontology rests on three commitments: state-centrism, materialism, and structuralism. Firstly, state-centrism requires justification. Why states, rather than individuals, multinational corporations, or international organisations? The answer is that states occupy a categorically different position in the international system. States alone possess the legitimate monopoly on organised violence within a defined territory (Weber, 1919). This matters because in an anarchic system, the capacity to deploy organised violence is the ultimate arbiter of outcomes. Though MNCs and NGOs can shape markets and norms, they cannot guarantee a population’s survival. Post-1945 proliferation of MNCs, NGOs and international organisations have not displaced this logic, with states remaining the primary actors (Babic, Fichtner, and Heemskerk, 2017; Lenz, 2017). The New Wars literature (Kaldor, 1999), often cited against state-centrism, in fact confirms the logic that the most destructive contemporary conflicts occur precisely where state authority has collapsed, producing the Hobbesian condition realism predicts. Similarly, the rising influence of human security approaches has not fundamentally challenged the dominance of realism’s state-centric ontology. (Chandler,2008). Realism’s second ontological commitment is materialism. The driving variable of international politics is capabilities rather than intentions (Waltz, 1979). Under anarchy, states cannot credibly verify the intentions of other states; intentions are liable to change, difficult to track, and are often misrepresented (Fearon, 1995). States that fall behind in relative power become vulnerable regardless of other states’ current intentions because intentions can change faster than military capacity (Mearsheimer, 2001). This structural constraint is confirmed by contemporary alliance behaviour: the EU’s rearmament following Russia’s 2022 invasion, China’s military build-up, and NATO’s eastern expansion are all driven by capability assessments rather than a convergence of ideology. Realists’ focus on capabilities over intentions has continued to dominate the discipline (Schmidt, 2020), for example in work on mass atrocities (Valentino, Huth, and Balch-Lindsay, 2004). Finally, realism’s ontological commitment to structuralism continues to be disciplinarily influential. Drawing on Bhaskar, Wight establishes that a realist ontology ‘embodies a commitment to transphenomenality – going beyond appearances to underlying structures which endure longer than those appearances and generate or make them possible’ (Wight, 2006). Applied to IR, the anarchic structure of the international system is the generative mechanism that produces state behaviour across time and context. International institutions and norms are expressions of the underlying distribution of power among states (Gilpin, 1981). Campbell (1992) argues that states actively produce representations of threat to reproduce their own identity and legitimacy, cited by Wight as the extreme position that ‘there is nothing outside of discourse’ (Wight 2006). But even if identity is partly constituted through discourse, the material capacity differential between states and other actors remains real and independent of how it is framed. Realism’s ontology is the substrate upon which rival theories build – the condition they implicitly assume when they acknowledge that cooperation is bounded or that institutions cannot compel states against their core interests.Secondly, Realism remains the discipline’s most progressive research programme. According to Lakatos, a research programme is judged by whether it makes novel predictions at the frontier moments where existing frameworks and systems are tested (Lakatos, 1978); and it is progressive when changes in its ‘protective belt’ of secondary theories (1) generate new predictions or explanations and (2) these are corroborated rather than invented after the fact (Lakatos, 1978). Firstly, realism has remained a progressive research programme under Lakatos’ conception because it has continued to generate a unique number of sub-theories and clarifications with considerable explanatory and predictive power (Julian, 2010 in Kheyrian, 2019). For example, Walt’s balance-of-threat theory refined realism’s capabilities ontology to explain why states balance against proximate and offensive threats, rather than mechanically against all change in capabilities (Walt, 1987); similarly, Christensen and Snyder integrated perceptions of the offence-defence balance to predict chain-ganging or buck-passing in multipolar systems (Christensen and Snyder, 1990). Furthermore, auxiliary realist theories have remained highly predictive: offensive realists, for example, successfully predicted and convincingly explained the role of NATO expansion in provoking Russia’s invasion of Ukraine (Mendes, 2022). Importantly for Lakatos’ conception, realism has successfully adapted its ‘protective belt’ of auxiliary theories whilst retaining its core theoretical commitments: for example, by explaining departures from balancing through changing incentives promoting bandwagoning (Schweller, 1994; 1997). Similarly, neo-realism has integrated state capacity, elite cohesion, and leaders’ perceptions into a realist conception of international relations (Rose, 1998; Schweller, 2006; Ripsman, Taliaferro and Lobell, 2016). Contrary to Vasquez claims that such refinements render realism degenerative by insulating Waltzian balancing theory from disconfirmation (Vasquez, 1997), judging realism solely by a crude balance-of-power proposition artificially narrows a progressive research programme (Walt, 1997). Compared with liberalism or constructivism, realism has produced the most testable explanations of great-power competition, alliances, deterrence, and security under anarchy.
Finally, realism provides the most convincing account of conflict and emergency politics. Cox (1981) distinguished problem-solving theory from critical theory, and realism is the best problem-solving theory because it identifies the conditions under which order breaks down and predicts the moments in which conflict becomes likely. Realism’s critics point to long periods of inter-war or post-war periods during which states appeared to transcend realism’s fundamental assumptions of conflictual state behaviour: particularly dyadic democratic peace (Doyle, 1983), the increasing role of international organisations (Mearsheimer, 1994), or economic interdependence that was supposed to be detrimental to state sovereignty and risk aversion (Gartzke and Lupu, 2012). This period of relative peace is, however, best explained by realist theories. For example, Gowa (1994) explains post-1945 democratic peace with states’ common interest in containing the Soviet Union. Similarly, Gilpin (1981) explains the stability of shared liberal norms as arising from the systemic dominance of a hegemonic power. Importantly, therefore, Gilpin’s framework predicted the contemporary decline of multilateral institutions and increasing interstate competition alongside the decline of American hegemony and changing structural conditions have indeed forced liberal states to revert to realist behaviour. Germany had spent seventy years constructing a pacifist national identity yet abandoned its opposition to arms exports to conflict zones within weeks of Russia’s 2022 invasion. Gilpin’s framework also applies to sub-state actors: when central state authority starts to dismantle, ethnic groups find themselves in conditions not wholly dissimilar to Hobbes’ state of nature – facing the security dilemma without a sovereign to solve it (Posen, 1993). This can be seen in the spiral of defensive arming and pre-emotive violence that characterises civil wars across post-colonial Africa and the Middle East. Liberal peace is, therefore, bounded within a broader anarchic system in which structural pressures are always present and; when pressures reach a threshold, such as a shift in the balance of power, the liberal structure dissolves. Between crises, institutions do indeed lower transaction costs and reduce information asymmetries, encouraging trade with low tariffs and cooperation. But security communities are themselves contingent on structural conditions, and rival theorists implicitly acknowledge this. ‘Outside such security communities, there is always a risk that, in the absence of friendly understanding, the dispute may intensify into something not containable by peaceful methods’ (Jackson and Jones, 2017). Wendt (1992) himself concedes that realist game theory is appropriate where identities can be assumed constant in the short term. Keohane also concedes that institutions cannot force states to act against their own selfish interest (Walt, 1998). Realism therefore identifies in advance the conditions under which other theories will fail and successfully explains the conflicts that follow. It is precisely this ability that makes realism the most fundamental, with war as its justification. Furthermore, classical realism’s emphasis on prudence and historical judgement makes it better equipped than either liberalism or constructivism to guide policy in the context of this contemporary increase in both interstate and within-state conflict (Kirshner, 2010). On the question of China’s rise, a classical realist framework directs policymakers towards the structural pressures that rising powers generate, whereas a liberal framework directs deeper economic integration on the assumption that interdependence will curb China’s behaviour, thereby underestimating the forces most likely to produce conflict (Kirshner, 2010). Furthermore, conflict is the most important problem to explain, analogous to Pascal’s Wager. Applied to IR, it would mean that the cost of wrongly applying a liberal framework during a period of crisis is catastrophic, as the failure to arm and anticipate conflict could result in the annihilation of a state (Pascal, 1670). The cost of wrongly applying a realist framework during a period of liberal cooperation is merely suboptimal, for example an over-investment in defence and missed opportunities for multilateral agreements. These costs are not equivalent, and their asymmetry suggests what IR theory is ultimately about conflict. War remains the most existential problem of international relations (Levy and Thompson, 2010), and realism its most fundamental explanation.
In summary, therefore, realism excels uniquely under three different conceptions of by which theories should be judged. It provides the discipline’s fundamental ontology, establishing what exists and what drives international interactions and outcomes – an account that has withstood challenges from postmodernism, constructivism, and liberalism alike, each of which depends on realist structural conditions it itself cannot explain. It is its most progressive research programme in the Lakatosian sense, generating novel predictions that have been corroborated throughout time (from the bipolarity system during the Cold War to the gradual erosion of American hegemony and the rise of alternative great powers). And it provides a uniquely problem-solving explanation to the increasingly significant problem of conflict. Realism alone identifies in advance the conditions under which order dissolves, explains the conflicts that follow, and grants policymakers with the realist outlook to navigate during times of crises.
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