The supermajority is a McGuffin. It's the McGuffin in the story being told by Alba Party politicians. It serves no purpose other than to make the story more appealing.
We are all aware of how that fateful phrase 'once in a generation' has come to haunt Scotland's cause. I don't doubt there are times when both Alex Salmond and Nicola Sturgeon wish they'd never offered up that particular hostage to fortune. What makes it truly regrettable is that they could easily have left it out. It wasn't essential. There are other ways of saying the same thing. Not so with the word 'supermajority'. It's not a throwaway remark. It refers to a very specific concept. A concept which is very much part of this election campaign. There isn't really an alternative. There may be other ways of saying the same thing. But none, I suspect, that wouldn't sound painfully contrived. We're stuck with it now.