While ethical principles and objective values belong to the realm of science rather than subjective opinion, we should not conclude that objective values cannot vary from individual to individual or from context to context, particularly at the level of concrete values. Individuals may have different hierarchies of objective values, especially in the diverse circumstances in which they find themselves. For example, a man stranded on a desert island has food, but lacks fresh water; a woman stranded in the wilderness has access to a potable stream, but not to food. For the man, water has greater objective value than food, while the reverse holds for the woman. Distinguishing between the relative objective values of food and water to these two individuals, however, is clearly quite different from claiming that these values are just a matter of "opinion," with respect to either individual.

Contrary to the common presumption that facts and values belong to separate realms, objective values and moral principles are seen here to be a special category of facts. In the ethical context of choices among actions, the concept good applies to those action alternatives that constitute well-functioning for the individual. The term "good" as used here is a natural extension of its meaning in Section 2. The science of ethics can also be viewed as the identification of well-functioning within the context of purposeful, volitional action.