[In the following review, Weberman explains Habermas's contribution to the field of discourse ethics, defining his methodology and its application to ethics.]

[Moral Consciousness and Communicative Action] is a well-translated edition of a book that first appeared in 1983. It has been expanded to include a fifth, more recent essay. The last three essays (two of which are short treatises in themselves) address pivotal issues in ethical theory, such as cognitivism, justification, Kantianism, and moral psychology. They contain the most definitive statement yet of Habermas's original contribution to the field: discourse ethics. It should be noted that analytic moral philosophers will find this book both accessible and relevant.

The first two essays deal more generally with the legitimate aims of philosophy and social science, but they also clarify the methodological assumptions underlying Habermas's ethics. Habermas argues that philosophy should no longer regard itself as an entirely distinct type of aprioristic inquiry serving as the judge and usher (Platzanweiser) for all purported claims to truth. This repudiation of foundationalism and dethronement of philosophy is said to follow from the historicity of our cognitive achievements and the impossibility of ultimate justification (moral and epistemological). Although it has led some to abandon all attempts at justification, Habermas is at great pains not to give up ship. Against Rorty, he argues: "Even a philosophy that has been taught its limits by pragmatism and hermeneutics will not be able to find a resting place in edifying conversation outside the sciences without immediately being drawn back into argumentation, that is, justificatory discourse." Sharing many of Rorty's premises, Habermas nevertheless arrives at different conclusions. He proposes not the abandonment, but the transformation of philosophy.

Habermas's transformed philosophy attempts to steer a middle course between aprioristic foundationalism and relativistic contextualism. Absolutely unwilling to restrict the evaluation of standards of rationality and morality to the bounds of a given culture, he engages in a "rational reconstruction" of the transcendental conditions of the various kinds of competence that we possess. What makes this different from foundationalism is that these transcendental conditions are "weak"—that is, historically contingent and (in part) empirically discoverable and falsifiable. The point is to discover in these conditions criteria for the rational assessment of moral and theoretical questions. This is the method; we can now turn to its deployment in ethics.

The treatment of ethics in this book can be divided into five parts: (1) the defense of ethical cognitivism; (2) the formulation and justification of the principle of universalization; (3) the appeal made to moral psychology; (4) the role of discourse in determining universalizability; and (5) the nonsubstantive, procedural character of moral theory.

(1) Habermas has long opposed ethical skepticism and subjectivism. Here he argues that moral rightness is not a naturalistic property, but a "higher-level" predicate like truth. However, this does not mean that moral judgments are true in the same way as empirical propositions. Moral judgments have their own kind of legitimacy that derives from the reasoning inherent in moral argumentation.

(2) For Habermas, moral argumentation must be based on a Kantian-like principle of universalization. His version of that principle, (U), requires that a valid norm be not only consistently universalizable, but also acceptable to all concerned parties. This stronger stipulation is motivated by the recognition that any one person's test for universalizability will be parochial to that person's preferences.

Habermas's justification of (U) takes the form of a "transcendental-pragmatic" argument that "show(s) that the principle of universalization … is implied by the presuppositions of argumentation in general" such that participation in argumentation accompanied by the disavowal of some such principle constitutes a "performative contradiction." Habermas maintains that implicit in argumentation are procedural rules that require equal opportunities for all participants and that the recognition of such rules "amounts to implicitly acknowledging (U)." Habermas mentions but does not lay to rest two problems with this derivation. First, individuals are free to opt out of argumentation. Second, recognizing certain rules of argumentation would not seem to entail recognizing similar rules for action. Whatever the cogency of the argument, Habermas says that it does not provide an ultimate justification or Kantian-like deduction of (U), but only shows that there are no plausible alternatives to (U). On his account, (U) has only "hypothetical" status, meaning that its universality and interpretation must be empirically corroborated. What remains puzzling are Habermas's reasons for not taking his argument to be as strong as any demonstration of necessary presuppositions and for thinking that it requires empirical confirmation.

(3) Habermas seeks further grounding for (U) in Kohlberg's theory of moral development, in which the possession of universal ethical principles represents the highest stage of moral consciousness. Yet it is hard to see how facts about psychological moral development are supposed to corroborate Habermas's philosophical argument aside from mapping onto or "fit(ting) into the same pattern," especially since Habermas concedes that "the empirical theory presupposes the validity of the normative theory it uses" and that the two stand in a "relationship of mutual dependence." In fact, Habermas's discussion serves principally to illuminate, reinterpret, and undergird Kohlberg's theoretical framework, and not the other way round.

(4) Perhaps the most original feature of Habermas's ethics is his insistence on the role of discourse. His strong formulation of the principle of universalization resembles the impartiality demanded by Rawls's veil of ignorance. However, Habermas argues that the test of universalizability "cannot be handled monologically but require[s] … a process of discursive will formation … a 'real' process of argumentation." In the last, more recent essay, Habermas defends discourse ethics against various criticisms including those leveled by Hegel against Kant (formalism, abstractness).

(5) Despite his departure from Kant's formalism through the inclusion of discourse, Habermas concedes and embraces a different kind of formalism. Discourse ethics is and must remain a procedural theory or a minimalist ethics that cannot provide "substantive guidelines" to questions concerning the good life. In accordance with liberalism and in recognition of the difference between cultures, Habermas leaves substantive moral issues to be decided by the actual process of public discourse.