Complexity and Quantum in International Relations
Authors: Snyder Greta Fowler , Hui Andre 
Published: March 2023

Even as work in the natural sciences has shown the Newtonian understanding of the world to be faulty, Newtonianism still pervades the field of International Relations (IR). Moved by the challenges to Newtonianism emanating from various fields, IR scholars have turned to complexity theory or quantum physics for an alternative onto-epistemological basis on which to build a post-Newtonian IR. This article provides researchers with a map that allows them to not only better see and navigate the differences within both complexity and quantum theory and the IR work that draws from each, but also to recognize the similarities across these bodies of work. Complexity theory highlights and engages systems (biological, social, meteorological, technological, and more) characterized by emergence, self-organization, nonlinearity, unpredictability, openness, and adaptation—systems that are fundamentally different from the self-regulating mechanic systems that comprise the Newtonian world. Complexity-grounded IR research, following complexity research more generally, falls into one of two categories. Through “restricted complexity” approaches, researchers use simulation or modeling to derive knowledge about the dynamics of complex social and political systems and the effect of different kinds of interventions. Researchers who take “general complexity” approaches, by contrast, stress the openness and entwinement of complex systems as well as unpredictability that is not exclusively the result of epistemological limitations; they offer critical re-theorizations of phenomena central to IR while also using qualitative methods to demonstrate how complexity-informed understandings can improve various kinds of practices. “Restricted complexity” seems to have gained the most traction in IR, but overall, complexity has had limited uptake. Quantum physics reveals a world with ineluctable randomness, in which measurement is creative rather than reflective, and where objects shift form and seem to be connected in ways that are strange from a Newtonian perspective. IR research that builds from a quantum base tends to draw from one of two categories of quantum physical interpretation—the “Copenhagen Interpretation” or pan-psychism—though more exist. Unlike the complexity IR community, the quantum IR community is ecumenical; given the deep ongoing debates about quantum mechanics and its meaning, embracing different ways of “quantizing” IR makes sense. Most quantum IR work to date stresses the utility of the conceptual tools that quantum physics provides us to rethink a wide variety of socio-political phenomena and hedges on questions of the nature of reality, even as the major theoretical tracts on quantum social science take strong ontological stances. Developing critiques and alternative positive visions for IR on the basis of either complexity theory or quantum work has been an important first step in enabling a post-Newtonian IR. To advance their agenda, however, the critics of Newtonian IR should start engaging each other and carefully interrogate the relationship between different strands of complexity and quantum theory. There are a number of key points of overlap between the work in the general complexity strand and the Copenhagen Interpretation–inspired philosophy of agential realism, and as of 2022 there exists only one major effort to bring these strands of quantum and complexity together to found a post–Newtonian IR. A coordinated post-Newtonian challenge that brings complexity-grounded IR scholars together with quantum-grounded IR scholars under a common banner may be necessary to wake IR from what Emilian Kavalski calls its “deep Newtonian slumber.” The pay-off, post–Newtonian IR scholars argue, will be a deeper understanding of, as well as more effective and ethical engagement with and in, a non-Newtonian world.