SIMPLY PUT, ETHICS is the study of the principles of right and wrong. Ethicists seek to know and to advise how to do good. However, this définition puts the subject into a deep quandary because, as the simple child's prayer says, “God is good, God is great…” and then goodness is an attribute of God and hence difficult to know. The difficulty of knowing what is good is at the core of the many types of ethics and many of the disputes over what is ethical and what is not. The sources of ethical principles have been nature or religion. Those who seek to develop naturalistic ethical systems use reason to identify principles that are consistent with human nature. For example, Benedict de Spinoza developed ...