Reading Professor Caplan’s thoughtful review of our book, The Peace Continuum, several thoughts came to mind. To begin, it is clear that our overall mission is the same. We both wish to encourage individuals to shift from studying and trying to understand political conflict/violence to studying and trying to understand peace. Additionally, we both feel that this objective is best achieved by providing a theoretically informed conception, as well as a detailed investigation of some evidence. This said, our missions diverge in important ways, and this is reflected in the comments/criticisms that Caplan made about The Peace Continuum.

For example, our joint scholarly book was very much influenced by the idea of not trying to force coauthors to adopt one approach over another. Indeed, we each entered our book project with the idea of having a delightful conversation about peace and how to study it without trying to convert the others. Interestingly, we ended up embodying the very principles that we attempted to highlight within the book by co-evolving toward an understanding of peace. For example, through the process of writing the book, I came a bit closer to the idea of how economic transactions could really mean something very different from finance, whereas Regan and Melander saw themselves constantly referring to civil war. In contrast, Caplan seemed to be interested in directing the reader in a particular direction. It thus makes sense that he questions some of our ideas, measures, and analyses. For example, he maintains that occasionally we made conceptual leaps and provided justifications that were unreasonable.

Many of Caplan’s remarks seem to suggest that if we had a better grasp of theory or if we had laid out our theories in greater detail, then we might have made different or better choices. But it is unclear what Caplan (or most social scientists) actually means by “theory” and how it should be evaluated. We were clearly concerned with such issues, because we felt that good measurement and analysis rested on good theoretical foundations, which were sorely missing in much of the literature on peace. Which way should one go, however?

Our answer to this question was not singular. Rather, we purposefully drew on distinct inspirations for theory development and followed the logic contained therein to develop distinct approaches to the study and measurement of peace. For example, Regan was fond of Boulding and Wright with attention to proxy measures, Melander was fond of Clausewitz and feminist theory while giving attention to human rights/equality issues, and I was fond of Eckstein, as well as assessing intergroup relations across levels of analysis. Ours was an effort to incite and invite comment and criticism as each of us brought our own theoretical perspectives to bear on the study of peace. We also tried to push as many different conventions as possible, and in this spirit Caplan’s comments take us exactly where we wanted to go. Does an argument about economic behavior have implications for political behavior? Should we consider how different groups are treated individually or together? And do peace-building efforts work? This is the new frontier: peace.