Recasting what I’ve said above, a difficulty here is that “ought”—which I repeat is ill-defined—tends to refer to concrete actions or abstentions.
If we take your standard way of construing things relatively the difficulty comes out quickly:
- X is more choice-worthy than Y
- Therefore one ought to prefer X to Y
(2) is not a concrete action or abstention, and this is why folks will deny that it is an ‘ought’ of the relevant kind. You can’t get a standard ‘ought’ such as, “One ought not murder,” from a premise like (1),
It may be the case that a fact/value separation entails an is/ought separation, but it’s not so clear that closing the former closes the latter.
(See also my archived post here.)