but (bt; bt when unstressed) KEY
Middle English, from Old English btan; see ud- in Indo-European roots
Traditional grammarians have worried over what form the pronoun ought to take when but is used to indicate an exception in sentences such as No one but I (or No one but me) has read it. Some have argued that but is a conjunction in these sentences and therefore should be followed by the nominative form I. However, many of these grammarians have gone on to argue somewhat inconsistently that the accusative form me is appropriate when the but phrase occurs at the end of a sentence, as in No one has read it but me. While this treatment of the construction has a considerable weight of precedent on its side and cannot be regarded as incorrect, a strong case can be made on grammatical grounds for treating this use of but as a preposition. For one thing, if but were truly a conjunction here, we would expect the verb to agree in person and number with the noun or pronoun following but; we would then say No one but the students have read it. What is more, if but were a true conjunction here we would not expect that it could be moved to the end of a clause, as in No one has read it but the students. Note that we cannot use the conjunction and in a similar way, saying John left and everyone else in the class in place of John and everyone else in the class left. These observations suggest that but is best considered as a preposition here and followed by accusative forms such as me and them in all positions: No one but me has read it. No one has read it but me. These recommendations are supported by 73 percent of the Usage Panel when the but phrase precedes the verb and by 93 percent when the but phrase follows the verb.·But is redundant when used together with however, as in But the army, however, went on with its plans; one or the other word should be eliminated.·But is generally not followed by a comma. Correct written style requires Kim wanted to go, but we stayed, not Kim wanted to go, but, we stayed.·But may be used to begin a sentence at all levels of style. See Usage Notes at and, cannot, doubt, however, I1.