A commenter asks a good question: "What do anti-prescriptivists tell their own children?"

My children are 2 and 3, and I'm told that at those ages it's more effective just to speak around your children the way you want them to speak, rather than setting rules for them. But I've certainly thought about what I ought to tell my children eventually; here are a few thoughts, with the understanding that "no battle plan survives contact with the enemy."

1. Be age-appropriate. A nuanced rule that may work for an older teenager might not work well for a younger child.

2. Teach children to speak and write in ways that will serve them well. My goal isn't to make sure that my child follows the technical rules of grammar. My goal is to make sure that he can speak and write in ways that are clear, that make him look educated, and that will make him seem pleasant and careful rather than pompous and offputting.

There's nothing wrong with the word "ain't," which has been used for centuries, and which I can find no abstract logical reason for condemning. It's just that today using it will lead quite a few people to think the less of you -- much more so than splitting infinitives would, for instance -- and the safe bet is to avoid it, except in fairly clearly jocular contexts. Likewise, there are lots of sesquipedalian words that aren't "wrong," but that one generally shouldn't use (though one should know in case others use them).

3. Teach older children to be skeptical of language myths. I plan to teach my children to be skeptical generally. But language is one area where I've come across especially many enduring myths, including myths -- about grammar, usage, etymology, and more. Children should learn that, so that they can develop their skepticism, and so that they can better learn what the actual rules are (and of course there are rules, just rules that are dictated by actual usage).

4. Explain to older children that English is a grown order, not a made order. This is itself an interesting and useful observation, but it may also help them think about how other things (such as markets) are largely grown orders.

5. Try to get my children to be interested in -- even fascinated by -- the language. I get a lot of pleasure out of thinking, reading, and talking about language, and I hope they will, too. And I think that thinking and caring about language will make one a more knowledgeable, careful, and effective user of the language.

6. Teach children not to correct others' grammar and usage, except in certain contexts and manners in which such correction is socially acceptable. As I noted before, that's both a good way of avoiding social friction, and a good way of avoiding the embarrassment of finding that the speaker you're correcting was actually quite right, and that your correction was incorrect.