So, you've got your pearl-handled revolver levelled at the megalomaniac's bonce. You 've just made a pretty speech about your values- which - rather jarringly for the late 19th century- include democracy- and the ghost of your true love (clad all in white) has been nodding along in smug agreement. The megalomaniac sneers that you're too weak to pull the trigger and turns his back. You concur and, having fluted something about how it's morally superior to be weak, put a bullet into the steam pipe of his Doomsday machine. You can't possibly know what you're going to achieve by this, but at least no-one is going to be able to call you a murderer. Luckily everything works out for the best in the best of all possible worlds and the megalomaniac gets reduced to catsmeat by the banks of steam-powered machine guns you've inadvertently triggered.
Real life is not like this. Most choices sting. Only in cheap fiction do you get offered a Blairite third way which sends you victorious without a stain on your conscience.
And that's why I don't believe Pullman is as serious a writer as his reputation suggests. I wouldn't mind so much if he wasn't also so preachy. It's that little speech about liberal values that precedes the cop-out that makes me want to kick him.
Oh- and that Doomsday machine in the railway carriage. The reason no-one ever actually developed such a weapon is because it's pants. You'd get to use it once- in a surprise attack- after which the opposition would take it out of the equation by digging up the tracks.