Habermas's moral theory goes by the name of “discourse ethics”. The name itself is potentially misleading, given developments in Habermas's position since he first unveiled his discourse ethics in 1983. Many philosophers understand ethics as broadly equivalent to moral theory, the normative study of moral practices, and discourse ethics is one such theory. But Habermas also uses the term “ethical” in a narrow sense, to refer to issues having to do with personal fulfilment and political self-determination, which he distinguishes from questions of moral right and wrong. This distinction has antecedents in German thought. Rejecting the Aristotelian amalgamation of moral virtue and happiness, Kant insisted that morality had to do with obligations that were unconditionally binding on all rational agents, whereas the constituents of happiness varied from person to person, time to time, and culture to culture. Today this basic contrast between morality and ethics tends to appear as the difference between the “right” and the “good”, or justice and the good life. In the context of such a distinction, discourse ethics is more accurately designated as a “discourse theory of morality” or a theory of justice.

A number of key concepts undergird Habermas's discourse theory of morality. To avoid misunderstanding at the outset, it helps to begin with two concepts that help us situate his approach to morality. First, as the opening paragraph implies, discourse ethics presupposes a particular conception of the moral domain, as distinct from other areas of practical reason.