Precising Definitions

Precising definitions are used to resolve vagueness. They are used to draw a sharp (or sharper) boundary around the things to which a term refers, when this collection has a fuzzy or indeterminate boundary in ordi- nary usage. For example, it is not important for most purposes to decide how big a population center must be in order to count as a city rather than as a town. We can deal with the borderline cases by using such phrases as “very small city” or “quite a large town.” It will not make much difference which phrase we use on most occasions. Yet it is not hard to imagine a situa- tion in which it might make a difference whether a center of population is a city or not. As a city, it might be eligible for development funds that are not available to towns. Here a precising definition—a definition that draws a sharp boundary where none formerly existed—would be useful.

Precising definitions are, in effect, combinations of stipulative definitions and dictionary definitions. Like stipulative definitions, they involve a choice. One could define a city as any population center with more than 50,000 peo- ple, or one could decide to decrease the minimum to 30,000 people. Precising definitions are not completely arbitrary, however, because they usually should conform to the generally accepted meaning of a term. It would be un- reasonable to define a city as any population center with more than seven- teen people. Dictionary definitions, thus, set limits to precising definitions.

Precising definitions are also not arbitrary in another way: There can be good reasons to prefer one precising definition over another, when adopting the preferred definition will have better effects than the alternative. If devel- opment funds are to be distributed only to cities, then to define cities as hav- ing more than 50,000 people will deny those funds to smaller population centers with, say, 10,000 people. Consequently, we need some reason to re- solve the vagueness of the term “city” in one way rather than another. In this case, the choice might be based on the amount of funds available for devel- opment. In a more dramatic example, a precising definition of “death” might be used to resolve controversial issues about euthanasia—about what doc- tors may or must do to patients who are near death—and then our choices between possible precising definitions might be based on our deepest value commitments. In any case, we need some argument to show that one precis- ing definition is better than other alternatives.