Trust emerged as a dimension of social relations in modern society along with risk. Risk became inherent in behaviours when, with the segmentation of social roles, there developed an in-built limit to systemically based expectations. Potential dissonance between the different aspects of roles increased, revealing these two new phenomena characteristic of modern forms of social relations: risk and decided trust. This evolution was reflected in phenomena such as the development of new forms of friendship and civility, the transformation of honour into conscience, and the appearance of compassionate marriage; in ideas of the public and private as separate spheres; and in the idea at the heart of the modern conception of private life, of the individual as moral, autonomous and having the power to act. As diverse as these social phenomena may appear, they are, in some respects, all part of a whole, connected to new terms of solidarity that define the modern world and the terms of our interactions within it.