Two colleagues came to me with a question: Is it incorrect to begin a sentence with and or but? I told them that beginning sentences with and or but is neither a grammatical violation nor a usage breach.
One colleague couldn't believe it; he had been taught all through school that a good writer never begins a sentence with and or but. I pointed out that a writer may choose for a stylistic reason to avoid such sentences, but that the "rule" is a myth.
Even Fowler's "Modern English Usage," published in 1926, considered this erroneous edict to be a "lingering superstition." Bryan A. Garner in "Garner's Modern American Usage" calls it "rank superstition."
The Chicago Manual of Style says this:
There is a widespread belief -- one with no historical or grammatical foundation -- that it is an error to begin a sentence with a conjunction such as and, but or so. In fact, a substantial percentage (often as many as 10 percent) of the sentences in first-rate writing begin with conjunctions. It has been so for centuries, and even the most conservative grammarians have followed this practice.
So if you are a teacher who still tells your students that it is incorrect to begin a sentence with and or but, please stop. You can tell them, instead, that they should avoid such use because there are still superstitious people who might bug them or grade them down. You can tell them to use such constructions sparingly.
But it is perfectly fine to start sentences with and or but. And I will stand up to anyone and say so.