VAGUENESS

Perhaps the most common form of unclarity is vagueness. It arises when a concept applies along a continuum or a series of very small changes. The standard example is baldness. A person with a full head of hair is not bald. A person without a hair on his head is bald. In between, however, is a range of cases in which we cannot say definitely whether the person is bald or not. These are called borderline cases. Here we say something less definite, such as that this person is “going bald.”

Our inability to apply the concept of baldness in a borderline case is not due to ignorance of the number of hairs on the person’s head. It will not help to count the number of hairs there. Even if we knew the exact number, we would still not be able to say whether the person was bald or not. The same is true of most adjectives that concern properties admitting of degrees—for example, “rich,” “healthy,” “tall,” “wise,” and “ruthless.”

For the most part, imprecision—the lack of sharply defined limits— causes little difficulty. In fact, this is a useful feature of our language, for suppose we did have to count the number of grains of salt between our fin- gers to determine whether or not we hold a pinch of salt. It would take a long time to follow a simple recipe that calls for a pinch of salt.

Yet difficulties can arise when borderline cases themselves are at issue. Suppose that a state passes a law forbidding all actions that offend a large number of people. There will be many cases that clearly fall under this law and many cases that clearly do not fall under it. There will also be many cases in which it will not be clear whether or not they fall under this law. Laws are sometimes declared unconstitutional for this very reason. Here we shall say that the law is vague. In calling the law vague, we are criticizing it. We are not simply noticing the existence of borderline cases, for there will usually be borderline cases no matter how careful we are. Instead, we are saying that there are too many borderline cases for this context. More pre- cisely, we shall say that an expression in a given context is used vaguely if it leaves open too wide a range of borderline cases for the successful and legit- imate use of that expression in that context.