In the first chapter we adopted a phenomenological approach (i.e. from the meaning perspective of a participant in a familiar lifeworld practice) in order to work out the humanist core of the rational moral principle from the normative logic of interpersonal relations, independently, at this stage, of certain ‘schools’ of ethics. With this step alone, of course, we have not achieved a complete rational foundation of the moral principle. In the history of ethics the moral principle has also often been more intuitively grasped than rationally well-grounded; a number of developmental steps were necessary until, finally, in most recent times, modern philosophical ethics developed the categorial means for a convincing, strictly reflective explication of the moral point of view that can be regarded as a sufficient rational foundation.

In order to understand this reflective explication or justification of the moral point of view it is useful to trace briefly the most important intellectual and philosophical historical stages leading to it. It is basically possible to distinguish two elementary lines of development. Along the one line an increasing differentiation between ethical and strategic reciprocity takes place permitting a purification of rational ethics from aspects of interpersonal reciprocity that are external to morality. Along the other line there is a progressive generalization of the reciprocity principle from the concrete reciprocity of two opposites (alter and ego) to the abstract principle of universalization. Both lines of development are inextricably intertwined in the various interpretations of the moral point of view.