Descriptive and Prescriptive

There is a lot of confusion about what "descriptive" and "prescriptive" grammar mean. I'm here to straighten you out. I'm not a linguist, but often I have to play one in the classroom. This is what I've learned, mostly from reading Language Log:

All linguistics is descriptive, in the sense that it tries to describe what the grammar of a language actually is, to discover the inner laws of a language. A descriptive grammarian does, in fact, think that there are ungrammatical sentences. For example, people in English say "By no means do I agree." They don't say *"By no means I agree." Grammar is largely unconscious, because nobody pulls aside a 4-year old and teaches her this rule: After an expression like "by no means," invert the subject and the verb. In fact, I do not even know, myself, the set of circumstances the require this inversion. I could figure it out perhaps, but then I would be doing linguistics.* Speakers of the language don't need to know this information to perform this inversion. I do it perfectly every time.

When faced with a prescription, or a recommendation of usage, the descriptive linguist tries to see whether it is a real grammatical rule or a zombie rule. For example, my second sentence in this post ends with a preposition. It is a perfectly good grammatical sentence in English, right? You can't say "*I'm here out you to straighten" or *"I'm here to straighten out you." So probably the idea of not ending a sentence with a preposition is a fake rule that doesn't have anything to do with English grammar. Linguists would also look to the writing of great and / or prestigious writers to see what they actually do, rather than deriving grammatical rules from principles of logic or from their own prejudices. If all the great writers in French use the language in a certain way, this cannot be wrong, because there is no grammar god to overrule the norm established by the language in its actual use, the norma loquendi. Grammar is actually evidence based, in this sense.

I wouldn't write "I'm here to straighten you out" in an academic paper. It's too informal. The descriptive grammarian knows that there are differences in register and dialect, but never confuses these differences with grammar per se. A dialect of English, even a stigmatized one, is going to have its own grammar, or its own rules, that the linguist might be interested in studying. A dialect considered substandard is still governed by unconscious rules. The prescriptivist is too intent on stigmatizing and peeving to even notice that there might be something interesting going on in a different dialect of a language.

The ordinary person uses the word grammar to refer to a wide range of issues: spelling and punctuation, usage and dialect, register, even pronunciation. A person like this often only perceives "grammar" when there is a violation, usually a violation of a rule that isn't even a rule in the first place. The linguist tends to reserve the word grammar for syntactical relationships.

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*Possibly the rule is "When the first word of a sentence is a negative adverbial type thing, invert the subject and verb." To see if I am right, my next step would be to see if these conditions apply. I know that I would say "Never have I heard of such a thing" but not "*Always do I go to bed at one." I am getting somewhere, very slowly.