OK, there's this nagging problem I have. Sort of an obsession. I push it to the back of my mind, where it stays quiescent for months, causing me no grief. Then it re-emerges, always re-emerges. Help me, dagblog community. HELP ME!

I blame Genghis for this latest relapse. In a comment to a post by Orlando (below), he wrote:

"A lying Mrs. Tebow would have no significance on the abortion debate. But nor would an honest Mrs. Tebow."

This is wrong. Wrong, wrong, wrong! Not Mrs. Tebow. I mean the combination of the words "but" and "nor." Substitute the word "neither," and it rolls off the tongue and/or the printed page. But "but nor" definitely does not; it jars my virtual ear. Where does this barbarism come from? Do they teach it in American schools?

I have never heard this phrase uttered in real life, or seen it submitted by a Canadian writer during more than three decades as a copy editor. I have only encountered it on the internet, in the texts of such otherwise reputable bloggers as Ezra Klein, Ed Kilgore, Tony Karon and -- as I noted above -- Genghis. Clearly some people think "but nor" is not only acceptable, but grammatically prescribed. 

Kilgore, for example, wrote on TPM: 

A huge number of Republicans didn't endorse or campaign for Barry Goldwater in 1964, but nor did they endorse or campaign for Lyndon Johnson. 

Clearly, there is some school of thought -- some authority, some grammarian, some respected author, perhaps some "language" columnist -- backing this construction.

My half-century-old Fowler's backs me up at least partially when it condemns the very similar usage "and nor." Addition of the "and," it says, is "clumsy." There is no mention of "but nor," perhaps because that usage was unknown 50 years ago.

At the very least, we have a pleonasm here, as in, "But he did not consider, however, that ..."
I think that is the problem in the above quotation: the writer realizes, when he gets to a certain point in the sentence, that he did not signal clearly enough, early enough, the contrast that he intended to draw. He probably should have backtracked and written:

Although a huge number of Republicans didn't endorse or campaign for Barry Goldwater in 1964, neither did they endorse or campaign for Lyndon Johnson.

A British or Canadian writer might even drop the "although" altogether, and simply preface "neither" by a semicolon. If one adamantly insists on keeping the "but," it's clearly less offensive to use "neither" with it, rather than "nor."

Help me out here, dagbloggers. And any grammarians who may be listening in. Either convince me there is some logical reason for "but nor" to exist, or join my campaign to stamp it out before it enters the actual spoken language.

Thank you.