Social constructivist research in international relations (IR) has a complicated relationship with international ethics. As is the case with most academic schools of thought, constructivists define themselves through a series of differentiations from other approaches. These early differentiations closed off possible areas for complementary research by defining some approaches as either implicitly or explicitly not constructivist. 1 In the case of constructivism, the intellectual context in which it emerged in the late 1980s and early 1990s led to three crucial differentiations. First, constructivism was an explicitly idealist approach to IR. This idealism enabled constructivism to differentiate itself from the two dominant materialist approaches in 1980s IR theory—neorealism and historical materialism. The neorealists grounded their explanations of international politics in the material capabilities (often reduced to military power) of states. 2 The historical materialists premised their understandings of world politics in the economic base of the mode of production and took ideas to be part of an ideological superstructure, the content of which was determined by the economic base. 3 In contrast to both positions, second-generation constructivists argue that materiality only acquired its social significance through its ideational interpretation. 4 In Alexander Wendt’s famous example, how a state’s material capabilities will be interpreted by other states very much depends upon the pre-existing relationship those two states have with each other. The United States will treat a military training exercise by Cuba as threatening, whereas an identical military training exercise by Canada will be interpreted as an ally fulfilling its military obligations under NATO. 5