In my own idiolect, "might could be" need not mean exactly the same thing as "maybe" and "perhaps." Suppose you tell me that my neighbor has been accused of stealing from the petty cash at his workplace, and you've asked me if I think he's really guilty of that. I might would then say one of these sequences in response to your question:As I understood Pullum's point, it was that the might in double modals might have become an adverb, basically like maybe. And for me, that works pretty well. Take this sentence:
1. "Maybe." [Or "Perhaps."]
2. "Might could be."
Example #1, either version, is neutral; it just means what it says -- that I'm willing to accept as a possibility that my neighbor is guilty of the alleged pecadillo. Example #2, on the other hand, is biased. It means that I'm on my neighbor's side, leaning toward a belief that he didn't do what he's accused of, and inclined also to believe that even if he is guilty he had a reason for what he did that I would consider adequate justification for the action.
- You might ought reconsider that.
- You maybe ought reconsider that.
This stuff is so pragmatically complex and intonation and context carry so much weight that I'm far from sure exactly how to get at the possible differences between maybe + modal and might + modal. (And I'm the world's worst at syntactic intuitions, to boot.) But I also can't see an obvious parallel adverbial replacement for ought in ought could, ought might, ought would.
Let's just keep playing the modal game … .
The image is from here, and there really is a "Modal Game" — free download!