Prescriptive grammar attempts to define how a language should be used. It’s important and necessary, because it maintains a touchstone that keeps language from diversifying too widely. Without it, eventually we might no longer understand each other’s speech or writing. Schools teach prescriptive grammar, giving us all a common standard of usage.
Descriptive grammar reflects how people actually speak and write, in practice. Real people in casual situations say “ain’t” and “gonna,” and put sentences together in a different order than their schoolteachers prescribed. Descriptive grammar has its own structure and it follows rules even when the rules are not obvious or codified. Socially, the only question in descriptive grammar is, “Did the other person understand what you meant?”
When the guy across the hall from me says, “You doin’ a’ight, sweetheart?” I know perfectly well what he means. That’s descriptive language, a real person talking the way he talks. When a Yankee, probably with Irish ancestors, says to me, “Howaya?” he’s asking pretty much the same question. To gripe that one should say “Are you doing all right?” and the other should say “How are you?” would be both silly and rude. Both are giving a simple greeting, and a possible response is something along the lines of “Fine, an’ you?”
Each type of grammar has its place. When writing an academic paper or a mainstream novel, or drafting a query letter to an agent, prescriptive grammar is the way to go. When chatting with a friend or neighbor, insisting on prescriptive usage is likely to make you unpopular, and worse yet disrupt the normal flow of congenial conversation. If you could figure out their intention clearly enough to be able to correct them, the goal of communication was met, and telling them to speak differently will create conflict instead of conversation.
“A’ight?”
Sidney
“When writing an academic paper or a mainstream novel, or drafting a query letter to an agent, prescriptive grammar is the way to go.”
Academic paper, probably. Query letter, not necessarily. Novel, absolutely no.
In a novel, the narrator and the speakers of dialogue, should express themselves in the way people express themselves. They should speak like the people in the world of the novel would speak, not like strict grammarians. No offense to college professors, but you don’t want everyone, including your narrator, to speak like a college professor.) In a query letter, you don’t want to break all the rules of grammar, but again you want to have a “voice” that may require you to break the “rules” sometimes.
Part of your confusion here is that your examples of descriptive grammar only show people speaking in dialect. But descriptive grammar is is about much more than dialect. A descriptive grammarian would say that a sentence is “grammatical” if a native speaker of the language would naturally say it. For example regular people often end sentences with a preposition or use split infinitives against the the rules that a strict prescriptivist might suggest are necessary.
S. Lee Rouland
My brain has a problem with descriptive grammar. If you tell me “the man was laying on the concrete” my brain asks “what was he laying on the concrete?”
My brain recasts sentences. “I only am free on Friday” recasts to “I am free only on Friday.”
Aaarrrgghhh
Marie Brack
I hear you. Such common but incorrect usage might occur in written dialogue, but I’d need the speaker to also use other colloquialisms to make it clear it’s that person’s own dialect.
What I meant to get at with this was that we make no friends by correcting people in real life, unless they’ve asked for help with mainstreaming their speech for some reason.