1. Introduction In this paper I wish to consider the following related questions: (i) Can a system of morality be justified?; (ii) Why should one act morally?; (iii) How can others be persuaded to act morally? Clearly none of these questions is new, and moral philosophers have proposed a variety of responses to them over the centuries without reaching any general agreement. Nevertheless, because these questions are fundamental to any practical application of moral theory, it is worthwhile to continue to reflect upon them. For Jewish, Christian and Muslim societies, the justification of morality is the Word of God as expressed in the Bible and Koran. Given an authoritative text containing basic moral premises, the appropriate method for obtaining rules of conduct is a process of logical deduction from those premises to conclusions. However, if we focus our inquiry on European and American societies in the present century, the decline of belief in religious authority has undermined this approach to moral theory for many people. This monumental change-for morality-may be attributed to many factors. An increase in multicultural studies has emphasized the wide variety of beliefs that human beings hold, which may have led more people to doubt that any one of them is authoritative. A number of writers over the years have commented on the correspondence of specific religious beliefs with one's society of birth, again leading thoughtful individuals to question the authority of their childhood religious beliefs. As a general sociological observation, one can point to a positive correlation between increasing educational level and a diminished belief in the authority of religious texts. When thoughtful persons reject religious authority as the basis of morality, it becomes necessa ...