The brilliant discussion in Chapter 3 of Robert Nozick's Anarchy, State, and Utopia (ASU) is vitiated by an illicit slide between “some” and “all” or, better, between “to some extent” and “entirely.” In this chapter Nozick discusses the moral theory background to his Locke an libertarian doctrine of individual moral rights. He seeks to show that structural features of the account of moral requirements and permissions that most of us accept turn out to be reasons also to accept the more controversial Lockean libertarianism.

The brilliant part of the discussion describes the structure of a non-consequentialist deontological moral theory that denies that each person ought always to do whatever would produce the impartially best outcome, even if the idea of the best outcome is interpreted as the greatest overall fulfillment of individual moral rights ranked by their moral importance. In this connection Nozick introduces the idea of a “side constraint” and of a morality that consists of side constraints, in whole or in part. This discussion advances our understanding of moral theory. We are all in Nozick's debt for this advance even if at the end of the day the case for accepting a consequentialist theory proves compelling.