Good

Another pervasive difference would involve "subjective" versus "objective" conceptions of the good. At its crudest, a subjective view would simply identify the good for a given person as what that person "prefers" or "desires." This appears to be the working conception of "the good" employed in economic theory. A number of views, especially in the empiricist tradition, tend toward this conception. For the "positivist" school, because value judgments are not scientifically verifiable, they can amount to no more than expressions of what one likes or desires. For an important strain in eighteenth-century British thought (the Scots Adam Smith and David Hume being perhaps its most important representatives), the good is understood in terms of one's preferences under ideal (e.g., personally disinterested, emotionally calm) circumstances.

At the other extreme, views in the tradition of Plato (c. 428–348 or 347 B.C.E.) construe "the good" as a kind of object of abstract contemplation. This object, then, is not constituted by our preferences or desires; it exists as an objective feature of the universe—according to Plato's analogy in the Republic, like the sun shedding light on all other things.

There is a related point of difference between subjective and objective views. In the former, the good is fundamentally an object of noncognitive attitudes such as desire or will. If, however, the good is conceived as an object existing independently of the human mind, it is natural to construe it as primarily an object of knowledge. Critics of the objective view—most prominently Hume—claim that it cannot account for the "action-guiding" nature of values and moral discourse generally. Mere contemplation of an object does not necessarily affect one's desires and will; but recognition that something is good surely does have this effect. For their part, defenders of an objective view have often replied that a subjective conception cannot account for genuine moral disagreement. They point out that a subjective account of a moral disagreement (in which person A says "x is good" while B says that "x is not good") will imply that it is merely a case of A saying "I desire x" and B saying "I don't desire x "—which is no real disagreement.