Kemerling 97 (Garth, professor of philosophy at Newberry College, http://www.philosophypages.com/lg/e05.htm)
We've seen that sloppy or misleading use of ordinary language can seriously limit our ability tocreate and communicate correct reasoning. As philosopher John Locke pointed out three centuries ago, the achievement of human knowledge is often hampered by the use of words without fixed signification. Needless controversy is sometimes produced and perpetuatedby an unacknowledged ambiguity in the application of key terms. We can distinguish disputes of three sorts: Genuine disputes involve disagreement about whether or not some specific proposition is true. Since the people engaged in a genuine dispute agree on the meaning of the words by means of which they convey their respective positions, each of them can propose and assess logical arguments that might eventually lead to a resolution of their differences. Merely verbal disputes, on the other hand, arise entirely from ambiguities in the language used to express the positions of the disputants. A verbal dispute disappears entirely once the people involved arrive at an agreement on the meaning of their terms, since doing so reveals their underlying agreement in belief. Apparently verbal but really genuine disputes can also occur, of course. In cases of this sort, the resolution of every ambiguity only reveals an underlying genuine dispute. Once that's been discovered, it can be addressed fruitfully by appropriate methods of reasoning. We can save a lot of time, sharpen our reasoning abilities, and communicate with each other more effectively if we watch for disagreements about the meaning of words and try to resolve them whenever we can. Kinds of Definition The most common way of preventing or eliminating differences in the use of languages is by agreeing on the definition of our terms. Since these explicit accounts of the meaning of a word or phrase can be offered in distinct contexts and employed in the service of different goals, it's useful to distinguish definitions of several kinds: A lexical definition simply reports the way in which a term is already used within a language community. The goal here is to inform someone else of the accepted meaning of the term, so the definition is more or less correct depending upon the accuracy with which it captures that usage. In these pages, my definitions of technical terms of logic are lexical because they are intended to inform you about the way in which these terms are actually employed within the discipline of logic. At the other extreme, a stipulative definition freely assigns meaningto a completely new term, creating a usage that had never previously existed. Since the goal in this case is to propose the adoption of shared use of a novel term, there are no existing standards against which to compare it, and the definition is always correct (though it might fail to win acceptance if it turns out to be inapt or useless). If I now decree that we will henceforth refer to Presidential speeches delivered in French as "glorsherfs," I have made a (probably pointless) stipulative definition. Combining these two techniques is often an effective way to reduce the vagueness of a word or phrase. These precising definitions begin with the lexical definition of a term but then propose to sharpen it by stipulating more narrow limits on its use. Here, the lexical part must be correct and the stipulative portion should appropriately reduce the troublesome vagueness. If the USPS announces that "proper notification of a change of address" means that an official form containing the relevant information must be received by the local post office no later than four days prior to the effective date of the change, it has offered a (possibly useful) precising definition.