In This Article Expand or collapse the "in this article" section Systems Theory

  • Introduction
  • General Overviews
  • Origins and Dynamics of the International System
  • Early System-Level Approaches in IR
  • Nature of the International System
  • The Second Image Reversed
  • Sociological-Constructivist Theories
  • Empirical Investigations

International Relations Systems Theory
Eric Hamilton
  • LAST REVIEWED: 25 October 2018
  • LAST MODIFIED: 25 October 2018
  • DOI: 10.1093/obo/9780199743292-0243


Systems theories of international relations (IR) focus on the structure of the international system to explain the behavior and interactions of the system’s units. The units consist primarily of states, which collectively constitute a system of states. Most systems theories treat the relationship between the international system and states as reciprocal, but explanatory preference is often given to the former in shaping the behavior and interactions of the latter. The formal treatment of the international system and its impact on states developed in the second half of the 20th century, with systemic thinking becoming most central to IR after the publication of Kenneth Waltz’s Theory of International Politics (Waltz 1979, cited under General Overviews). For the next two decades, IR scholars grappled with the strengths and weaknesses of Waltz’s and others’ systems approaches. Systems theorizing remains an important approach to the study of international relations, but because individual theories are difficult to construct and empirically difficult to support, there is little agreement about the explanatory value of any of the particular theories discussed in this article. Moreover, the notion of an international “system” and how to define it remains contested among IR scholars.

General Overviews

There is no single introduction to systems theory in international relations (IR). The references in this section are general introductions to systems theory as it applies to politics in general (Easton 1965), or overviews of systems theory as parts of larger theoretical projects or surveys in IR. Waltz 1979 remains a good place to start for a thorough discussion of systemic versus reductionist theorizing. Levy and Thompson 2010 provides a comprehensive overview of system-level theories, focusing mainly on realist and hegemonic theories of conflict. Wendt 1999 follows Waltz’s systems approach but expands his conception to account for the role of unit-level factors and the importance of identity. Buzan and Little 2000 compares American and English School approaches to systems theory. James 2002 discusses the state of systems theorizing while introducing Mario Bunge’s systemism to IR. Patrick James also provides a summary of how some IR scholars have defined the international system, showing how contested and potentially problematic the concept remains. Braumoeller 2012, meanwhile, surveys systems theorizing in IR but faults mainstream work for not actually drawing on developments in systems theory outside the field. Albert, et al. 2010 attempts to draw on such developments by exploring the implications of systems theorizing in the social and natural sciences for IR. Finally, Jervis 1997 reminds us that systems are more complex than our theories assume, and that unintended consequences should be expected.

  • Albert, Mathias, Lars-Erik Cederman, and Alexander Wendt, eds. New Systems Theories of World Politics. New York: Palgrave Macmillan, 2010.

    Early-21st-century collection of essays that attempt to revive interest and establish a new research agenda in systems theorizing in IR by drawing on developments from the social and natural sciences.

  • Braumoeller, Bear F. The Great Powers and the International System: Systemic Theory in Empirical Perspective. Cambridge, UK: Cambridge University Press, 2012.

    DOI: 10.1017/CBO9780511793967

    One of the most recent and best overviews of systems theory in IR. Methodically surveys the different traditions of systemic theorizing that have developed in the field, while simultaneously developing a new systems theory based on a mathematical model.

  • Buzan, Barry, and Richard Little. International Systems in World History: Remaking the Study of International Relations. Oxford: Oxford University Press, 2000.

    Good historical overview of systemic thinking in American IR and the English School.

  • Easton, David. A Framework for Political Analysis. Englewood Cliffs, NJ: Prentice-Hall, 1965.

    Classic early metatheoretical text arguing for a systems approach to the study of politics. Defines political systems, describes their dynamics, and explains why they tend to persist.

  • James, Patrick. International Relations & Scientific Progress: Structural Realism Reconsidered. Columbus: Ohio State University Press, 2002.

    Great overview of systems theorizing in IR. Additionally and importantly, translates Bunge’s philosophical work on systemism into IR, expanding our understanding of the various explanatory relationships that exist at and between the system and unit levels. See James’s summary of various definitions of the international system in chapter 2.

  • Jervis, Robert. System Effects: Complexity in Political and Social Life. Princeton, NJ: Princeton University Press, 1997.

    Focuses on complexity and its unintended consequences in systems to critique prevailing systems theories in IR and offer a more nuanced approach.

  • Levy, Jack S., and William R. Thompson. Causes of War. Chichester, UK: Wiley-Blackwell, 2010.

    Comprehensive overview of system-level theories, focusing mainly on realist and hegemonic theories of conflict.

  • Waltz, Kenneth N. Theory of International Politics. Boston: McGraw-Hill, 1979.

    The formal articulation of neorealism and central text for debates about the nature of the international system and its impact on states. Remains a foundational text for understanding systems theorizing in general in IR. New edition published in 2010.

  • Wendt, Alexander. Social Theory of International Politics. Cambridge, UK: Cambridge University Press, 1999.

    DOI: 10.1017/CBO9780511612183

    Pivotal text in constructivism. Importantly, expands Waltz’s discussion of systems theory by including unit-level factors in systemic thinking, as well how the international system shapes state identity in addition to behavior and interactions.

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