I propose an analysis of negation in corrective "but" sentences (“negation…but…”, e.g. “Max doesn’t eat spinach but chard”) that parallels Wu’s (to appear) analysis of “either…or…” sentences, and suggests a novel view of negation as a coordinator (parallel to "either" in "either...or..." sentences). I argue that there are two positions for negation, one structurally higher than the other. Either position may be pronounced, but only the high position is interpreted. In addition, ellipsis deletes repeated material in the second conjunct. This analysis is consonant with previous proposals for the syntax of focus-sensitive operators such as the Question-particle and "only", suggesting that all focus-sensitive operators may have what I call bipartite syntax: there are two instances of the operator in a sentence. The lower position is semantically inert, and must c-command the focus. The higher position marks the semantic scope.
