Philips defends a middle ground between the view that there is a set of standards binding on rational beings as such (universalism) and the view that differences in morals reduce ultimately to matters of taste (skepticism). He begins with a sustained critique of universalist moral theories and of certain familiar approaches to concrete moral questions that presuppose them (most appeals to intuitions, respect-for-persons moralities, and versions of contractarianism and wide reflective equilibrium).

He goes on to criticize major recent attempts to develop nonuniversalist alternatives to skepticism, arguing that they rely on excessively abstract and philosophically indefensible preference satisfaction theories of the good.

According to Philips's positive alternative, ethics as social artifact, moral codes are social instruments and they are justified to the extent that they effectively do their jobs, which is to promote reasonably valued ways of life. Accordingly, he argues that different standards may be justified for different societies, depending on their circumstances, traditions, and current institutions.

His account of a reasonably valued way of life depends on a "falsifiability" approach to reasonable values according to which existing values are treated as reasonable unless good arguments can be made against them. He describes many strategies for making such arguments, the upshot being an approach to the justification of moral standards that is sufficiently "grounded" to settle many controversies and to mark off areas in which rational persons are free to disagree.

It also explains why the weight of a moral consideration may vary reasonably from one "domain" of social life to another. An original approach to the uses and limits of reason in ethics, Between Universalism and Skepticism provides a theoretical basis for approaching actual moral controversies and questions of applied and professional ethics in a systematic way.