[T]he authority of philosophy consists in its being a theoretical subject. If philosophers are going to offer moral opinions, they need to have some claim to attention. They are not, as philosophers, necessarily gifted with unusual insight or imagination, and they may not have a significantly wide experience or knowledge of the world. Their claim to attention rests on their capacity for drawing distinctions, seeing the consequences of assumptions, and so forth: in general, on their ability to develop and control a theoretical structure. Their special contribution to substantive ethical issues, then, is likely to be found in a theoretical approach to them, and one of the most common enterprises in moral philosophy at the present time is the development of various ethical theories.
(Bernard Williams, "Ethics," chap. 10 in Philosophy: A Guide Through the Subject, ed. A. C. Grayling [New York: Oxford University Press, 1995], 545-82, at 549)
