(b) the historical presents are semantically imperfective. They are pragmatically marked in that they occur in slots where the perfective aspect would be unmarked.
The answer is 'b', of course. Thank you for the clarification.
And as Greeks have been saying for 2000 years, the historical present is marked for time, too, because they are semantically 'present' but occur is slots where a non-present would be expected.
This point is crucial. Once the AspectOnly people recognize that their 'semantic theory' gets overridden by pragmatics with aspect, they should have no theoretical objection to having their semantic theory overridden by pragmatics in time. their argument unravels from that point.
I am not sure about this argument. I see a difference between aspect and tense here. The imperfective of the historical present does not contradict the semantics of the sentence, it is just pragmatically marked. I do not expect to see any Vendlerian achievements (temporally indivisible as far as the linguistic expression goes) in historical presents, and if I understand you correctly, you don't either. With tense, the picture changes somewhat. Past time is incompatible with present time, whereas the imperfective aspect is compatible with anything that is not a Vendlerian achievement, even if it is marked. Therefore there is a fundamental difference between the two.
The issue may be somewhat related to how one defines the border between semantics and pragmatics. If one holds a view that semantics is uncancelable and that the semantics of the historical present cannot be imperfective present time because of historical presents, there is still no contradiction here, and it seems to me that your argument does not bite. I do not mean that I would agree with these presuppositions, but I suspect that many aspect-only people do.
The only difference between a pragmatic use of aspect and time is that 'past time' is easier to define on absolute terms, and 'perfective' requires more finesse and careful reading before the audience realizes that they are being sold the Brooklyn Bridge. (That is American slang for something bogus, false.) Because in theory, it is illegitimate for a person to allow a pragmatic use of aspect but then forbid a pragmatic use of 'absolute time'. This is why prototypicality theory and cognitive linguistics and complexity theory can be friends.
I agree that prototype theory is the way to go here, and the methodological foundation of aspect-only seems to contradict prototype theory, but I am not sure how convincing your argument is to those who have not bought the theory. For those who have, I am not sure how much it adds. Am I missing something or do I misunderstand your argument in some way?