A person is a monist about values if he thinks there is only one property the possession of which to some degree makes a thing intrinsically valuable. A person is a pluralist about values if he thinks there is more than one property whose presence in an object can make a difference to the object's intrinsic worth. Hedonism is a form of monism, at least if we count both pleasantness and unpleasantness as simply degrees of one kind of property (otherwise it is dualism). Usually, critics of hedonism are pluralists; but a nonhedonist could be a monist, thinking, perhaps, that knowledge or quality of character is the only property that makes something intrinsically worthwhile.
What kinds of thing might a nonhedonist think affect intrinsic worth? Such things as knowledge, strength of character or the possession of various virtues, human life, kindly deeds, suffering for one's community, keeping a promise it is hard to keep, grateful recognition of services done, beauty even if not enjoyed by anyone, a distribution of happiness among people in proportion to their merits. Some of these, we see, are properties of single conscious organisms (for example, knowledge and being alive); persons who confine "good-making" (those that affect intrinsic worth) qualities to this sort are personalists about values. Others of these are not properties of single conscious organisms (for example, the distribution of happiness according to merit); writers who believe there are "good-making" qualities of this kind, we shall call impersonalists about values (although the term may be misleading, since no impersonalist fails to allow that states of persons are of intrinsic worth). Correspondingly, we shall speak of personal and impersonal "good-making" qualities. Obviously, a hedonist is not only a monist but a personalist in his view about what makes for intrinsic worth. We might say that a personalist about values is one who counts only states of welfare as having intrinsic worth; but "welfare" is itself a rather vague term, although one widely used.
(Richard B. Brandt, Ethical Theory: The Problems of Normative and Critical Ethics, Prentice-Hall Philosophy Series, ed. Arthur E. Murphy [Englewood Cliffs, NJ: Prentice-Hall, 1959], 303-4 [italics in original])
