How do we get to have normative concepts? What does it take for a concept to be the concept of ought, or of good, say?
It seems neither necessary nor sufficient that one be disposed to apply the concept to just the things that are actually good. On the one hand, you could be mistaken about what things are good whilst still possessing the concept. On the other hand, you could have a non-normative concept which picks out the good items under some other, non-normative guise. (Suppose hedonism is true: the concept pleasure then picks out all the good things, but that doesn't make it the concept good.)
Plausibly, the connections to normative practices and behaviour are more important. When we judge that we ought to φ, we tend to be motivated to φ, and to feel some degree of guilt or shame if we fail to φ. When we judge that another ought to do something, we may blame (or otherwise think less of) them if they fail to do it. But couldn't these same behavioural dispositions be linked up to a non-normative concept, as a matter of brute psychological fact? The dispositions may then seem arbitrary to us in a way that our normative practices do not, but then again, we can imagine a relatively unreflective agent who never pauses to question their dispositions in this way. Brute behavioural dispositions combined with a lack of reflectiveness surely does not suffice for possession of normative concepts.
But then what's missing? One possibility is that we just need more cognitive and behavioural dispositions, linked up in the right way, to form a web that qualifies as a web of genuinely normative concepts. Such interconnections may well be necessary for full normative concept possession, but I still worry about whether it's sufficient.
A certain detachability from descriptive concepts seems important, at least for the pure/"thin" normative concepts like good and should. Whatever descriptive objects we tend to associate with these concepts (and their associated behaviours), we can imagine applying them differently instead, and indeed ask whether we should take different things to be what we 'should' do. That is, open questions can be raised about applying a normative concept to what we currently assume it applies to -- it's always an open question, in some sense, whether we are actually using the concept correctly. (As per Moral Twin Earth, we can imagine others sharing the same concept whilst applying it rather differently.)
Normative phenomenology also seems important. There's a distinct feel to normative thoughts, the feel of an imperative operating independently of our own wills, telling us what to do. Interesting questions can be raised about the order of explanation here: Is it in virtue of having a thought with normative content that we feel this distinctive normative phenomenology, or does the phenomenology in some sense come "first" and help to pin down the content of our thought as genuinely normative in nature?
It's a curious topic, and the right way to think about it remains highly non-obvious to me. Others' thoughts (or recommended readings) welcome!