I guess it is a question of definitions, but i think it really is not possible, for the reason that the space of possible test sets includes contradictory sets.

I guess it is a question of definitions, but i think it really is not possible, for the reason that the space of possible test sets includes contradictory sets. So if I ask you a simple question which is not in your training set, like "Does a Quigloth have eyes?", there can be two possible test sets, one where the answer is no, and one where the answer is yes. So a reply to this could be that questions have to be about the real world. But that is then the same "meta distribution" as I mentioned in my previous comment, and not out of distribution learning in the pure sense.