Few topics of discussion evoke more emotion than the correct use of language. Favorite subjects of such debate include the correct use of terms such as “disinterested” and “decimate,” which are commonly used to mean one thing, (“uninterested” and “devastated”, respectively, in the case of the examples cited), but which have other useful meanings in particular contexts.
Usually, in the course of such debate, someone will play what they take to be the trump card of “common usage,” establishing its authority on the word of “grammarians” or even “enlightened grammarians.” Thus, “decimated” it is implied does actually mean “devastated” whatever some may think it was that Appius Claudius Sabinus Inregillensis did in 471 BC, by ordering that one man in ten of Roman army that fled the field in a battle with the Volsci be selected by lot and executed.
The fact is, though, that there is, in the case of many if not most words, no such thing as common usage. Different people use particular words differently according to their age, experience, education, dialect, etc., and the same person uses particular words differently, depending on context and whether they are addressing the dog, a bunch of regular guys down the pub, or an academic seminar.
In fact, the appeal to the authority of the non-existent “common usage” appears chiefly to be a claim to superiority of the appellant’s particular pattern of language use, or as Bertrand Russell argued in the The British Journal for the Philosophy of Science (February, 1953),
What in fact they believe in is not common usage, as determined by mass observation, statistics, medians, standard deviations, and the rest of the apparatus. What they believe in is the usage of persons who have their amount of education, neither more nor less — less is illiteracy, more is pedantry — so we are given to understand.
There is also the implication of moral superiority of the speaker due to their democratic commitment on language use. However, as Russell pointed out:
Those who advocate common usage in philosophy sometimes speak in a manner that suggests the mystique of the ” common man.” They may admit that in organic chemistry there is need of long words, and that quantum physics requires formulae that are difficult
to translate into ordinary English, but philosophy (they think) is different. It is not the function of phlosophy — so they maintain — to teach something that uneducated people do not know ; on the contrary, its function is to teach superior persons that they are not as superior as they thought they were, and that those who are really superior can show their skill by making sense of common sense.