What an incredibly interesting thread.
Excuse brevity and crassness - in rush.
My position has changed quite dramatically over the last ten years. Like many others I feel that the rise of endgame fundamentalism in general, and 9/11 in particular, has shifted the terms of the debate.
I accept that there's probably a deal of naivety in this, and that 9/11 has been hugely useful in general, for quashing objections to all sorts of nefarious agendas.
And, in and of itself, my position-shift isn't logical: the value - moral, military, political, strategic - of a nuclear defence policy of course doesn't change because some new, really-really-bad thing comes into existence.
Nevertheless, a kind of relativism of horror is important to this debate. Nuclear defence, which during the Cold War never did, despite the fears of two generations, result in the degree of death and destruction which 9/11 visited on us in what felt like a millisecond, gains a strange kind of moral heft from the comparison.
Were we all creatures of logic, we would be able to take 9/11's terrible toll of 3000 dead, compare it to Nagasaki-Hiroshima's beyond-imagining 150-246,000, and take a deep breath. But we're not, and the suddenness, the incomprehensibility - the utter otherness - of the former has now replaced our horror of another Hiroshima.
All this psycho-social stuff is easily dismissed as nonsense in this context. But in a debate in which we discuss apocalypse, but in which there is disagreement amongst best strategic minds - and philosophers - about whether we can ever defend ourselves against threats which haven't yet been conceived - the tenor and quality of the terror we feel can be a useful moral guide.
The terror inflicted on ourselves and others during any particular course of action is morally significant; for me - in the absence of strategic certainties - the moral likelihood of the damage done to us all by engaging in the nuclear stand-off was enough to justify an anti-nuclear stance.
We used to live in world in which the citizens of the East faced those of the West in utter terror, and living in terror decreased our wellbeing.
I don't think that is the case any longer - apart from the massive geopolitical shift of the end of the cold war, we are no longer quite so politically naive, so in thrall to domestic propaganda, I don't think. And history, too, is on our side: we know that there was no apocalypse in the 40-odd years of the Cold War.
And - though it's certainly true that the spinning of MAD as its own raison-d'etre was an infuriatingly circular argument ("Because I exist, I should exist") - it's also demonstrably true that MAD worked.
Even though we now live in an utterly unpredictable world (as if we haven't always done so..) a locical course of action would be to continue with what has worked till now, while attempting to develop new strategies to deal with changing patterns of global aggression. Spread betting, as ST did.
ST - I think I can count on the fingers of no hands the times I've agreed with you so far, but I think you've argued very convincingly on this.