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What makes something a security threat? Who should be protected, and by what means? These questions have driven security studies since its emergence as a distinct field after World War II. The answers have never been settled. Instead, the subfield has developed through a series of competing frameworks, each offering a different diagnosis of danger and a different prescription for safety. Understanding security studies means tracing how these frameworks challenged, absorbed, and coexisted with one another.
Security studies first took shape under the influence of Classical Realism, which dominated from the late 1940s through the 1960s. Thinkers such as Hans Morgenthau argued that international politics is driven by a human will to power, making conflict inevitable. For Classical Realists, the state is the primary actor, and security means protecting territorial sovereignty against military threats. The framework treated power politics as a tragic constant: states could cooperate only temporarily, and war remained a permanent possibility.
By the 1970s, a new variant—Neorealism—narrowed the realist lens. Kenneth Waltz’s Theory of International Politics (1979) shifted explanation from human nature to the structure of the international system. Anarchy, not human ambition, forced states to prioritize survival. Neorealism preserved the state-centric focus of Classical Realism but replaced its psychological foundations with a systemic logic. This move made realism more parsimonious and testable, but also more rigid: change in state behavior could only come from shifts in the distribution of power, not from learning or norms.
Neorealism’s rise provoked a rival within the same rationalist family. Neoliberal Institutionalism, emerging in the late 1970s and 1980s, accepted Neorealism’s core assumptions—states are unitary, rational actors operating under anarchy—but drew different conclusions. Robert Keohane’s After Hegemony (1984) argued that institutions could reduce transaction costs and facilitate cooperation, even without a central authority. The resulting “neo-neo debate” was a family quarrel: both frameworks shared a positivist epistemology and a materialist ontology, but they disagreed over the possibility and durability of cooperation. Neoliberal Institutionalism coexisted with Neorealism as a competing rationalist alternative, not a wholesale replacement.
By the late 1980s and early 1990s, the end of the Cold War exposed a blind spot in both rationalist frameworks. Neither Neorealism nor Neoliberal Institutionalism could explain why the Soviet Union peacefully dissolved or why states suddenly redefined their interests. Constructivism, drawing on sociological theory, offered a different starting point: state interests are not fixed but are constituted by shared ideas, identities, and norms. Alexander Wendt’s 1992 article “Anarchy Is What States Make of It” directly challenged Neorealism’s claim that anarchy necessarily produces self-help. Constructivism did not reject the state as an actor, but it insisted that the meaning of power and security depends on intersubjective understanding. This framework transformed security studies by opening space for ideational change—such as the spread of human rights norms—that rationalist models could not capture.
Constructivism’s attention to meaning paved the way for a more radical departure: Critical Security Studies (CSS). CSS emerged in the 1990s as a subarea-family that coordinates several approaches sharing a rejection of state-centrism and positivism. Rather than asking how states can be more secure, CSS asks whose security is being prioritized and at whose expense. The family includes three main branches, each with a distinctive method and normative orientation.
Securitization Theory, developed by the Copenhagen School (notably Ole Wæver and Barry Buzan), treats security as a speech act: an issue becomes a security threat when a political actor successfully labels it as such, justifying extraordinary measures. Unlike Constructivism, which focuses on slow identity formation, Securitization Theory emphasizes the performative power of language in the moment. It remains analytically neutral about whether securitization is good or bad, though later work has examined its ethical implications.
The Welsh School, led by Ken Booth, takes a different path. It defines security as emancipation: freeing individuals from the structural oppressions—poverty, patriarchy, environmental degradation—that cause insecurity. Where Securitization Theory describes how threats are constructed, the Welsh School prescribes how security should be reimagined. This normative commitment puts it in tension with Securitization Theory’s descriptive stance, even though both reject state-centrism.
The Paris School, associated with Didier Bigo and others, draws on Pierre Bourdieu’s sociology to examine how security professionals—police, intelligence agencies, border guards—routinely produce insecurity through their everyday practices. Unlike the Welsh School’s macro-level emancipation or Securitization Theory’s focus on dramatic speech acts, the Paris School traces the mundane bureaucratic routines that expand surveillance and control. These three branches coexist within CSS, each offering a different lens on the same critical impulse.
Feminist Security Studies emerged alongside CSS but with a distinct focus. Scholars such as Cynthia Enloe and J. Ann Tickner argued that mainstream security studies ignored how gender hierarchies shape both war and peace. For feminists, security must be analyzed at multiple levels—from the battlefield to the household—and must include issues such as sexual violence, militarized masculinity, and the gendered division of labor in conflict zones. Feminist Security Studies shares CSS’s critique of state-centrism but adds a systematic attention to gender as a category of power.
Poststructuralist Security Studies, influenced by Michel Foucault and Jacques Derrida, goes further in questioning the very categories of security. It examines how security discourses produce the subjects they claim to protect—for example, how the “war on terror” constructs a dangerous “other” that justifies endless intervention. Poststructuralists share with feminists a suspicion of fixed identities, but they focus more on the linguistic and discursive mechanisms that make certain threats seem natural. Both frameworks have expanded the subfield’s toolkit beyond the state and the military, but they differ in emphasis: feminists foreground gender, while poststructuralists foreground discourse and deconstruction.
Today, no single framework dominates security studies. The field is deeply pluralistic, with different approaches occupying different niches. Neorealism and Neoliberal Institutionalism remain influential in policy-oriented and quantitative work, especially on interstate conflict and alliance politics. Constructivism leads in explaining identity-driven conflicts, norm diffusion, and the social construction of threats. Critical Security Studies—especially Securitization Theory—has become a standard tool for analyzing how issues like migration, climate change, and health are turned into security problems. Feminist and Poststructuralist approaches are more marginal but continue to push the field to reflect on its own assumptions.
What do the leading frameworks agree on? Most now accept that security is not a self-evident objective fact but is shaped by interpretation, politics, and power. Even rationalists have incorporated some ideational variables. What they disagree on is how far that insight goes. Rationalists still insist on material constraints and strategic calculation; constructivists emphasize shared meanings; critical theorists argue that security itself is a form of governance that must be questioned. The result is a field that remains vibrant and contested—a sign not of fragmentation but of a discipline grappling with the complexity of its subject.