I think it takes mental gymnastics to convince yourself that the situations are analogous.

It's a bit of self-deception, to make yourself feel better, perhaps? I find the comments above interesting - that the self-deception makes the switching of the tracks scenerio less ethical than the pushing off the bridge scenerio. I can see the point.

I'm imagining a military board room where the strategists are deciding to send in a battillion to get creamed in order to distract the enemy away from their true objective, and thus, end the war more quickly. It'd be a lot easier to make that decision in a board room than in the field surrounded by the doomed soldiers.