Lesser politicians say one thing and mean another. Our Prime Minister says one thing and its opposite and believes them both at the same time. As we're on the subject of atomic weapons we might consider applying Heisenberg's famous Uncertainty Principle to him. Not that the Prime Minister's uncertain about anything. No, but we may be forgiven for being uncertain about him.
Heisenberg said that we can know everything about where a Prime Minister is but nothing about where he's headed. Or we can know everything about where he's going but nothing about where he is at the moment. So Tony Blair announces that he wants to increase our nuclear capability and lead the world in nuclear disarmament. He can now go down in history as the man, A) who multiplied our ability to kill billions, and B) the man who halved our nuclear stockpile. That's quite a multidimensional legacy.
He conforms to the atomic logic - or the subatomic logic - that says we only want nuclear weapons because we don't want nuclear weapons. That's deterrence. It's also why they called it Mutually Assured Destruction (because of its acronym).
But when he says he wants to make it absolutely clear that we have total control over our system and that the Prime Minister alone has the power to press the button ... I found myself wondering what on earth he meant by that.
Anyway, it seems to be almost certain that he has decided that we shall update our weapons systems and we are to have a full, four-month debate on it. It offers to be a very interesting experience, with the Prime Minister taking on the David Dimbleby role.
I think he's up to it. The House certainly gave him an unusually easy ride. But it's hard to become indignant with someone who spends 15 per cent of every utterance saying your point is cogent, well-made and deserving of serious consideration. He also had a brilliant one-word argument that trumps all others: "France". If they've got one, we have to have one too. I'm sorry, but there it is.
Gratifyingly, points made in the House still enjoy an emotional weight, or resonance that television doesn't give them.
Ronnie Campbell said he didn't believe in our nuclear weapons because he didn't believe we'd ever use them. I hadn't heard that quite so deftly made before. Though, en passant, I don't know why he believes we'd never use them.
So it's entirely possible that this process will add a little lustre to the Commons; I hope it does. We may even learn whether the £20bn estimate for the upgrade includes VAT.
NB: I like Gordon Brown's new-found calm. He sits on the front bench chin lifted slightly, eyes slightly down, looking as though he's posing for his sculpted bust. To be hewn out of the side of Mount Rushmore.