Today, more than at any other time in human history, biologists are or should be concerned about the morality of biological research and newly developed technologies. Two questions confront any scientist or science student concerned about morality and the life sciences. Is there some theoretical framework that might be used to assist in deciding about moral matters? And how should people go about deciding matters of morality? This paper considers four ways in which people make moral decisions. These decisions are based upon Authority, Intuition, Science, and Ethical Reasoning (Duty and Consequentialist views).