Normative is one step beyond just being normal, it is that which establishes and reinforces what is normal. See formative, creative or persuasive for similarly constructed words.
In Philosophy and ethics a normative statement is a moral imperative, an explicit 'we should' statement.
But many of our norms are not explicitly told to us. We infer them from experience. Thus anything normal, in sufficient quantities, is normative. This is the stance of deconstructionism and literary criticism.
For instance, many children's stories, leaving aside the interesting and wacky ones, present a normal life situation for the child to learn from. You will find normative situations presented to you in all kinds of fiction: in books, TV and movies. The more clichéd, stereotyped, didactic, the more normative.
Ever notice how often the flawed or weird sidekick has the misfortune to be killed by the villain? That is normative.
We derive ought from is with the normative assumption that what is, is ought to be.
This, in my opinion, is part of the root of homophobia and other minority hatreds. It is not that homosexuality is unnatural (it happens, and therefore is natural), but that it is not what some are used to. It is not part of their inculcated norms. Some people can't see past that.
Much of childhood experience is normative. Children accept the way in which they are brought up as being normal and natural, even when it is unusual.
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