Four types of vagueness
To see the extent of the problem of distinguishing ambiguity from vagueness, let us consider the different types of vagueness. There four types are not unrelated to each other:
1. Referential vagueness
Referential vagueness, where the meaning of the lexical item is in principle clear enough, but it may be hard to decide whether or not the item can be applied to certain objects.
For example: city and town. Presumably we can at least roughly agree that a city is a place where a large collection of people live, and it is made up of a large number of houses; whereas a town is simply any place where a collection of people live, made up of a certain number of houses. Town can be small or large, but cities are big by definition. If we can agree that the meanings of the items need to have a specification along these lines, we shall certainly find difficulty in individual cases in deciding whether or not some place is city or town. Is Bradford a city? Notice that it will not do to specify as part of the meaning of the item that a city must contain a minimum number of inhabitants, for we can talk of Roman cities where the numbers might scarcely exceed that of a present-day village.