There's a 'should' either stated or implied.
Some confusion in that:
In economics “Normative Econ” often means axiom based approach. State “reasonable conditions on preferences and production functions” derive necessary implications. See… most of books like Mas Colell et al.
In common parlance, maybe in psych, I’ve hear “normative behaviour” used to mean something like “typical, normal, socially acceptable behaviour”
I don't think there's a perfect answer, but as a heuristic I defer to the logical positivists - if you can't even in principle find direct evidence for or against the statement by observing the physical world and you can't mathematically prove it, and on top of that it sounds like a statement about behaviour or action, then you're probably in normland.
Oh, I like this. Seems good to have a word for it, because it's a set of constraints that a lot of us try to fit our morality into. We don't want it to have logical contradictions. Seems icky. Though it does make me wonder what exactly I mean by 'logical contradiction'.