Abstract

The dissertation is an explanation and evaluation of ethical naturalism in its several senses. In Chapter Two, four senses of ethical naturalism are delimited as follows: definitional naturalism, according to which moral terms may be defined with non-evaluative, natural terms; synthetic naturalism, according to which moral properties may be identified with, though not definitionally reduced to, non-evaluative, natural properties; motivational naturalism, according to which motivation to act morally is a natural desire; and methodological naturalism, according to which moral philosophy may be helped to some degree by the sciences. Motivational and definitional naturalism are found to be true, and moral properties are reduced to properties which acts have relative to the ordinary altruistic and selfish desires of a society, i.e., its coherent set of moral values. Synthetic naturalism is argued to be false, while methodological naturalism is shown to be true only under a moderate interpretation. For upon consideration , the relevance of evolutionary biology and psychology to moral philosophy is shown to be slight