Few modern philosophers are convinced that the nature and availability of trust between human beings really is a central issue in the theoretical understanding of politics. This is in some ways surprising, since the most prominent recent movement in political philosophy, the largely North American dialogue about the content of social justice inaugurated by John Rawls (1972), has been strongly committed to the theoretical centrality of the idea of a contract: a free, but binding, agreement. The normative force of the standard of uncoerced choice by free and rational agents unites the great seventeenth-and eighteenth-century philosophical exponents of natural law and natural rights with modern contractarian critics of the claims of utility to serve as a uniform criterion for political and social decisions. But the two groups of thinkers differ drastically in their estimate of the practical significance of that normative force.

For early modern theorists of natural law (Locke, Rousseau, even Hobbes), there were the closest of ties between voluntary self-commitment, the obligatory force of a contract or promise, and the psychological and social foundations of human collective life. Fides, the duty to keep faith and the practical virtue of discharging that duty in the dependable fashion, was the foundation for social life in its entirety (Dunn 1985, chapter 2), the key practical capacity which made it possible for human beings to live with one another on tolerable terms at all.