It is a common misconception that a good writer doesn’t begin a sentence with a conjunction. Here’s a very nice passage that will illustrate that the truth is otherwise. Gilbert Highet was a Scottish-American classical scholar and teacher of the last century, and these two sentences are from his grand The Classical Tradition, published by the Oxford University Press in 1949. Note how the conjunction but begins the second sentence, alerting the reader to the contrasting (and perhaps surprising) idea to come. He is speaking here of Greco-Roman civilization:
It was, in many respects, a better thing than our own civilization until a few generations ago, and it may well prove to have been a better thing all in all. But we are so accustomed to contemplating the spectacle of human progress that we assume modern culture to be better than anything that preceded it.
A conjunction is one of the eight parts of speech of traditional grammar. Each part of speech names how a word is working grammatically in a given sentence, and the specific function of a conjunction is to connect, or associate, one word or phrase or clause to another. A simple enough idea, until we realize that things can be connected in many different logical ways. I might say, for example, that I have to go to the store to buy bread and lettuce, and the function of the conjunction and in that phrase would be merely to add one thing, one noun, to another. But the idea of addition, or accumulation, is different from the idea of contrast, or opposition, which is the distinct purpose of the conjunction but, as we can see it working, for example, in the sentence It’s sunny but cold today. I could have written sunny and cold, but if my intent was to contrast the actual cold temperature with the thought of warmth commonly associated with the sun, then the contrastive but would serve my purpose better (because my thought will be more accurate) than the additive and.
Now contrast, or opposition, is just the idea Highet intended to signal by beginning his second sentence with the conjunction but. His first sentence carries two assertions: that Greco-Roman civilization was “in many respects” better, and that it might ultimately prove to have been better in every respect. Two clear, parallel assertions. And so when the next word we read is but, understanding that the function of that conjunction is to mark an upcoming contrast, our attention is thereby placed perpendicular to the two parallel ideas and we are readied for this opposing thought: our assumption that modern culture is better than anything before it might not be correct, no matter how dazzled we are by all we’ve invented and enjoy.
Highet’s passage is compositionally involved, and his choice to array the opposition across two sentences helps him control his thoughts as he presents them. But it can help us to ask what other choices he might have had. Could he have replaced the period before but with a comma, combining the two sentences into one? Read the passage again with that change and you’ll see that the two opposing ideas slur together, buffing away the emphasis. He could, though, have used a semicolon where that same period is, still combining the two sentences into one, but now one so stately, almost statuesque, that its style would not have matched the general audience he was addressing.
Choices like these depend ultimately on the relationship one assumes to the ideas being expressed. Style is character, and character is a deep mystery. It can help as a basis, though, to understand the current rules of grammar together with their reasons, and there’s no argument against beginning a sentence with a conjunction—for all the reasons just mentioned.
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