That's a game-theoretical curiosity rather than an earnest desire to eliminate all of humanity. The point is to make a big show of being willing and able to com

That's a game-theoretical curiosity rather than an earnest desire to eliminate all of humanity. The point is to make a big show of being willing and able to commit mass murder, while fervently hoping it doesn't actually come to that. MAD is actually a result of people trying to prevent nuclear death - for themselves, at any rate. And I don't think human extinction is an intended outcome even in the very worst case (Dr Strangelove's Doomsday Device being, thankfully, a work of fiction). But of course you're right - it would be extremely unethical to say the least to actually retaliate in a MAD scenario. This fact is well known and widely discussed.