Define a pre-commitment by you to be blackmail if it makes me wish that I’d pre-pre-committed (and, of course, let you know that I’d pre-pre-committed) to not do the thing that you want in the event that you made that pre-commitment.
How does that do?
EDIT: Thinking about it more, this problem is just division of gains from trade. I’ll explain that more in a top-level comment.
Can we just use that as the definition?
Define a pre-commitment by you to be blackmail if it makes me wish that I’d pre-pre-committed (and, of course, let you know that I’d pre-pre-committed) to not do the thing that you want in the event that you made that pre-commitment.
How does that do?
EDIT: Thinking about it more, this problem is just division of gains from trade. I’ll explain that more in a top-level comment.
That’s the problem—every example I’ve come up with is covered by that definition.