I am grateful to Roseanne McManus for her thoughtful and incisive review. She raises two important interrelated questions. The first concerns the relationship between the book’s behavioral approach and rational choice, and the inevitable trade-offs involved in making simple models more complex: If it makes modeling tractable, why not reduce resolve to an actor’s cost of war? The second concerns the book’s adoption of an interactionist theory: Why not just conceptualize resolve as dispositional? I respond to both here in turn.

Although all models are inevitably simplifications, my sense is that the virtue of simplicity depends on the problem at hand. Following Richard Thaler (“Behavioral Economics: Past, Present, and Future,” American Economics Review 106 [2016]), it is perfectly reasonable for physicists to begin by modeling the behavior of objects in a vacuum, but at some point it becomes helpful to acknowledge the existence of air, particularly if one is trying to build an airplane. In the case of resolve, I argue that many of the difficulties that international relations scholars have experienced with explaining resolve comes precisely from attempting to collapse the concept into a situational straitjacket: Proclaiming that actors will be resolved when their costs of war are low and weak-willed when the costs of war are high is of limited value in and of itself if we want to explain why some actors persist in the face of mounting costs, while others back down—the very puzzle we frequently turn to resolve to explain. Moreover, although the book is often critical of how rational choice scholars have studied resolve, there is little inherent in rational choice that precludes the incorporation of a richer set of dispositional characteristics, and what are sometimes referred to as “nonstandard preferences” (e.g., Emilie M. Hafner-Burton et al., “The Behavioral Revolution and International Relations,” International Organization 71 [2017]). My quarrels are with the strategic choice approach’s “methodological bet” that greater theoretical progress can be made in IR by focusing on environmental features than on characteristics of actors themselves—not with the logic of rational choice itself.

The interactionist approach I employ in the book is borrowed from an earlier person–situation debate in psychology, which confronted the question of whether it was meaningful to talk about personality traits given the presence of cross-situational variation (e.g., Walter Mischel, Personality and Assessment [1968]). In this sense, it was similar to the agent-structure debate in IR, except that it led to a widely adopted solution: Rather than viewing traits as decontextualized and situation-free, psychologists adopted an interactionist approach, exploring how dispositional characteristics display conditional effects based on particular aspects of the environment. My approach in the book is similar, arguing that how much resolve actors display is a function of both dispositional traits and situational stakes.

As McManus rightly points out, these two sets of factors may operate in different ways; my view is that this makes it all the more important to study both in tandem. I am thus particularly appreciative of her call for political scientists to bridge the divide between the study of the origins of resolve (my focus here) and the study of the effects of signals of resolve (the subject of her important book), fruitful terrain for future scholarship.