F ifty years ago, the concept of a public good was understood only in casual terms. It took the formalizations of Paul Samuelson, Mancur Olson, and others in the 1960s to bring its remarkable properties to the full attention of the social science world. Those properties are its indivisibility — it cannot easily be divided up and parceled out to people according to their individual demand for it — its nonexcludability — people cannot easily be excluded from its use — and its nonsubtractibility — one person’s consumption or use of the good does not reduce the amount of the good available for the use of others. With these properties well in hand, scholars in various social science fields revolutionized thinking about public policy; 4, 5 the design of institutions; 7, 8, 9 obstacles and solutions to social dilemmas (prisoner’s dilemmas, public good dilemmas, commons dilemmas — articles on them now number in the thousands); the establishment of governments; 11 the outbreak of war; 13, 14 the failures of economic markets; 16 and so on. The concept of public goods was the centerpiece of the new field of rational choice, which made formidable inroads into the traditional fields of international relations, political science, economics, sociology, and psychology. The nearly moribund field of political economy was redefined and reinvigorated through exploration of applications of public good and related concepts. The articles in this issue attempt to extend the minirevolutions into yet another field, the field of evolutionary biology, by demonstrating (1) the crucial role that public goods may have played in the evolution of sharing behavior and collective identity, not exclusively, but primarily of the human sort; and (2) how public goods contribute to the explanation of evolved social behaviors, in particular, those behaviors that are precursors of the formation of the state. Foremost among them are religious ideology, national identity, and a host of behaviors that have resulted in the formation of the institutions of the state: law, hierarchy, and the structures and processes that provide and disperse public goods. This follows on Jared Diamond’s widely popular and well-reasoned books on the evolution of modern states and societies, and the conditions that provoke their collapse. In Guns, Germs, and Steel, Diamond describes in compelling fashion not only how varied ecologies created or stymied technological change, but also the conditions suited to the emergence of societies at various stages of development. In Collapse, he cites the general conditions determining the collapse of societies. Articles in this issue refer to what we believe is a crucial lacuna in Diamond’s work — the critical role of public-good provision as a purpose behind state formation, as an essential element of the creation of collective identities needed for state formation, and as a variable that lends support, and poses challenges, to the formation and maintenance of states over time. Peter Corning’s article on ‘‘Holistic Darwinism’’ warns us about overstating the importance of public goods. There are many paths to the evolution of human cooperation, affiliation, large-scale collective identity, and state formation, and activities that involve the dispersal of public goods constitute just one of those paths. Still, public goods seem to be at the heart of the rationale for state formation. Furthermore, their provision in the form of state institutions remains to be fully explained. The explanation of human cooperation, collective identity, as well as group and state formation, have been hampered by realization of the doi: 10.2990/26_2_2