This dissertation offers a partial history of ancient Greek international law from roughly 500 to 100 BCE as well as an explanation of the use of and compliance with international law by Greeks of those centuries that is grounded in legal sociology and social psychology. In other words it provides some answers to the questions, “Was there such a thing as Greek international law? If so, what did it consist in? And why did Greeks use it?” In the first chapter I show that Greeks recognized the existence of international law, regularly complied with its demands, and sometimes took concrete actions against those who violated it. I argue that there was a Greek international world occupied by political entities that we can reasonably call states, and that the rules governing behavior in this international world are reasonably called law. Hence it makes sense to speak of “Greek international law.” In Chapter 2 I present the theoretical framework by which I interpret Greek international law. This framework recognizes people as psychologically complex, driven by a wide variety of motives, and often acting on the basis of subconscious or unconscious factors.

Our psychologies are heavily “socialized” by our social environments. States, in turn, are socially and politically complex collections of psychologically complex humans. With reference to studies in social psychology and legal sociology, I interpret much legal behavior, and in particular law compliance, as the result of socialization processes rather than simply “rational” reactions to the deterrence aspects of legal punishment. Stressing in particular the role of group identity in encouraging people to create, comply with, and enforce rules, I argue that group identity formation and the legal socialization processes resulting from it take place both at local and at international scales. Because groups are created by and within social networks, I describe ways that international social networks and corresponding group identities were formed across the Greek world. In Chapters 3 and 4 I offer histories and interpretations of two aspects of Greek international law: syla, the customary law of self-help seizure; and symbola agreements, interstate judicial treaties by which poleis reciprocally granted to each other’s citizens certain substantive and procedural legal rights.

These legal institutions are known primarily from epigraphic sources, and I examine these sources while narrating the histories of syla and symbola through the Classical and Hellenistic eras, while interpreting syla and symbola in light of the theories of legal socialization and group identity presented in Chapter 2. In the final chapter I broaden the horizon and offer briefer overviews and interpretations of three other aspects of Greek international law (oaths, piracy, and federal leagues), suggesting some of the insights that a sociological approach can offer for understanding Greek international law. I argue that, for Greeks, international law, with its norms, its obligations, and its socially embedded nature, was continuous with and significantly overlapped with domestic law.