Yes it is possible to derive an
ought from an
is. Arthur Prior first pointed out the fact that the
naturalistic fallacy wasn't a fallacy in a book called "Logic and the Basis of Ethics" which is from the 30s or 40s.
Here's an example:
(1) He is a sea-captain.
(2) Therefore, he should do whatever a sea-captain should do.
(2) clearly follows from (1), and yet (1) is a descriptive claim, and (2) a normative one.
Two things to note about this example. First, the concept
sea-captain is a functional concept. There is something that sea-captains do, and it is perfectly objective whether some sea-captain is doing a good job as captain.
Second, the fact that the inference from (1) to (2) cannot be proven valid in ordinary first-order logic does not imply that that the inference isn't valid. Obviously, it is. Rather, one should simply say that the logic of normative inferences is just vastly, vastly more complicated than the baby logic everyone learns as an undergrad. This won't be surprising to people that have done graduate work in logic, or people who have done work in linguistics. But all the reasons to think that you can't derive an
is from and
ought turn out to just be working with a really impoverished logic. Just because you can't prove the fundamental theorem of calculus with arithmetic doesn't mean it isn't true. It just means you need better tools. The same holds true here.