all such valuations is ‘really false’ or ‘superfalse.’ All others are vague. Note that, in this conception of vagueness, if F is vague, so is -F. However, unlike fuzzy logic ‘F & -F’ is not evaluated as vague – it is false in every valuation and hence is superfalse. And ‘F 7 -F’ is supertrue. These are seen by some as positive features of the method of supervaluations, and as an argument against the whole fuzzy logic enterprise.
In fact there seem to be at least two distinct types of (linguistic) vagueness, and it is not at all clear that any of the previously mentioned logic approaches can deal with both. Without going into the details, we can just point out that the ‘sorites vagueness’ discussed above presumes an ordering on a continuous underlying scale; and it is the indistinguishability of adjacent points on this scale that gives rise to borderline cases. But there are examples of vague terms for which there is no such scale. A classic example is ‘religion’: there are a number of factors relevant to determining whether a social practice is a religion. Having none of these properties guarantees failing to be a religion, and having all of them guarantees being one. However, there is no continuum of the sorites variety here; for example, it is easy to distinguish possessing four from possessing five of the properties, unlike the sorites case where such a change is imperceptible. In the present type of vagueness, although we can tell these different cases apart, we just do not know whether to call the practice a religion or not. Furthermore, some of the properties (or combinations of properties) are more important or salient in determining whether the practice is a religion than are other properties or combinations. We might call this family resemblance vagueness: there are a number of clearly distinguishable conditions of varying degrees of importance, and family resemblance vagueness is attributed to there being no definite answer to the question, How many of which conditions are necessary for the term to apply? Other examples of family resemblance vagueness are ‘schizophrenia sufferer’, ‘sexual perversion’, and the venerable ‘game’.
A special subclass of family resemblance vagueness occurs when there are pairs of underlying properties that normally co-occur, but occasionally apply to different objects. Consider, e.g., ‘tributary’. When two rivers meet, one is usually considered a tributary of the other. Among the properties relevant to being a tributary rather than the main river are: relative volume of water and relative length. Normally, the shorter of the two rivers has a lesser volume, and in that case it is the tributary of the other. But occasionally the two properties do not co-occur and then there is a conflict, giving rise to a kind of vagueness we might call conflict vagueness. The term ‘tributary’ is vague because its background conditions admit of such conflicts: there are borderline cases when these two properties apply to different objects. To conclude: the fundamental philosophical problems involving vagueness are (1) to give an adequate characterization of what the phenomenon is, and (2) to characterize our ability to reason with these terms. These were the problems for the ancient philosophers, and they remain the problems for modern philosophers. See also DEFINITION , MEANING, PHILOSO- PHY OF LANGUAGE , TRUT. F.J.P. & I.Be.