Prescriptive versus Descriptive Rules

When debating terminology, I have several times run across the issue of prescriptive versus descriptive rules. A prescriptive rule states how people should use a word; a descriptive rule states how people do use a word.

For example, many people pronounce "nuclear" as "new-cue-ler". Webster's has even accepted this oddity as one among several pronunciations. But does Webster's inclusion of the pronunciation mean that it is "correct" to pronounce the word that way? I don't think so. The inclusion of the pronunciation is descriptive; they included the pronunciation because it describes how a significant portion of the English-speaking population pronounces the word. They are not endorsing the pronunciation.

Interestingly, the same sorts of issues arise in the rules of games. I have debated rules of poker, for example, with people who insist the rule they follow is "correct" because everyone seems to play that way. But when I look up the rules in an authoritative source, such as Hoyle's Rules of Games, I sometimes find that the "official" rules differ from the common way in which people play.

I favor acting according to prescriptive rules rather than descriptive rules. Discrepancies between prescriptive and descriptive rules typically arise from ignorance - a larger and larger number of people who aren't familiar with a traditional rule begin to behave differently until few people even know what the original rule was. I want my rules to be based on full knowledge of both common usage and history, which sometimes means dismissing common usage as based on ignorance.