Vagueness has become a central topic in analytic philosophy. It is obvious that much of our language is vague. Words like “fat,” “wealthy,” “friendly,” “tall,” “happy” are unquestionably vague: each is subject to borderline cases where the predicate in question neither clearly applies nor clearly fails to apply. Every concept that applies to the everyday world – every empirical concept – is subject to borderline cases, and hence is vague. One might think that the vagueness of our empirical concepts is to be explained by vagueness in the world; however, many philosophers begin with the presupposition that the reality to which our concepts apply is not vague: The standard view today is that reality itself is precise. Given the fact that all of our empirical evidence suggests that the world, as well as our language, is vague, one may wonder why philosophers are so intent on denying what seems obvious. Well, there is a reason.
Typically, interest in vagueness stems from interest in logic and semantics: Philosophers are looking for logic and semantics to handle vague language. Concern about logic and semantics leads one to treat vagueness in a way that preserves, for example, the law of excluded middle, according to which “p v ̴p” is a logical truth. And vagueness in the world would seem to threaten the law of excluded middle.