Realism is true---even constructivists and institutionalists concede it’s a prereq.
Joseph M. Grieco 2. Professor of Political Science at Duke University, in Durham, North Carolina. Realism and Institutionalism in International Studies: Modern Realist Theory and the Study of International Politics in the Twenty-First Century. University of Michigan Press. 35-36.
I. Modern realism helps us appreciate the impact of the anarchical structure of the international system on the preferences, strategies, interactions, and domestic institutions of states. Modern realist theory provides the strongest and clearest analysis of the peculiar (but not unique) setting in which states interact: the absence of a centralized authority reliably capable of providing protection and the redress of grievances. This political context, in turn, through processes of selection and socialization, has a constraining effect on the strategies that states are likely to pursue and even, at the limit, the preferences that they seek to satisfy in the international domain. In particular, modern realism provides us with the tools to appreciate that states that are co-located in a self-help system will be concerned about their security and their independence and, by consequence, the means by which they can retain some minimally acceptable level of both, or at least mitigate the harm that may be done to one or the other. In addition, modem realism helps us to apprehend the systemic sources of constraints on the amenability of national governments to work together even when they share common interests. Finally, realism sheds light on the observable behavior of many major states to resist rather than to acquiesce in the face of overwhelming power.
Other systems-level theories of international relations-for example, neoliberal institutionalism and social constructivism largely accept this modern realist depiction of world politics as the starting point for their own analyses.3 These approaches put themselves forward as fundamental alternatives to realist theory. However, in the main they do no more than suggest that not all of the inferences put forward by modem realism about world politics necessarily obtain at present, or they need not do so for all time. These alternative approaches are essentially "yes, but" commentaries on the realist understanding of world affairs.4