“Most of us would sacrifice one person to save five. It’s a pretty straightforward bit of moral math. But if we have to actually kill that person ourselves, the math gets fuzzy.
“That’s the lesson of the classic Trolley Problem, a moral puzzle that fried our brains in an episode we did about 11 years ago. Luckily, the Trolley Problem has always been little more than a thought experiment, mostly confined to conversations at a certain kind of cocktail party. That is until now. New technologies are forcing that moral quandry out of our philosophy departments and onto our streets. So today we revisit the Trolley Problem and wonder how a two-ton hunk of speeding metal will make moral calculations about life and death that we can’t even figure out ourselves.”