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Why is it incorrect to start a sentence with “and”?
In grammar school, my English teachers taught me that I should never begin a sentence with a conjunction.
Of course, that was before the advent of email, instant messages, text messages, Twitter, and Facebook updates.
My Question: Does the conversational nature of email allow us to begin sentences with conjunctions?
In matters of usage, everything is permitted, but not everything is correct.
We're allowed to begin sentences with upside-down question marks if we so choose, gleefully flexing the muscles of our free will, but that doesn't make it correct in English usage.
In this case, though, I regard the initial conjunction as grammatically correct. And as you'll find in Nohat's excellent answer to this question, many leading grammarians agree.
Don't let it stop there, though, because your question implies a larger one which I do find interesting: should the context of online communications be regarded as more akin to prose, or to speech?
There are two angles to look at this from: what is common, and what is correct.
Common usage in online forums, e-mails, and chats is predominantly conversational in tone. The majority of people on the Internet are treating it as a conversational context, not a written one.
This is a case where the rubrics of correct style are not yet in harmony with the popular usage. The major English style manuals continue to hold that a written word is a written word is a written word.
In order for harmony to be achieved, either the rules or the common usage will eventually change. If there's a bookie willing to take the bet, I'll lay my money on the rules changing first.
Why? Because we don't have village squares anymore. There's a reason we call many online communities "forums" - a reference to the original Roman Forum. The Internet is the public commons of the modern day, and I fully expect it will continue to be more conversational in tone than most other outlets for written expression.
Your grammar teacher was applying the rule: "If they do it too much, they should be told not to do it at all." Young language learners are generally not ready for nuanced discussions about when an initial coordinator is the appropriate choice. So to preclude a prevalence of "And then I .. " in written narratives, the teacher proscribes the use altogether.
[The quote comes from a Language Log post on the same topic. @JonathanVM above links to @Nohat's summary of the Language Log discussions, and here is another current debate on the issue.]
And why not?
Pay no attention to what they told you in grammar school.
Write the way you talk. That's what the best writers do.
