Yesterday morning my class had a think (under duress, of course) about the trolley problem, described graphically in the following short film.
It seems (from research in which people were asked to ponder the trolley problem during an MRI scan) that in the cranial war raging in us between emotional and rational centres, the emotional response gathers strength more quickly – those who pushed the man took longer to decide to do so, the neural pathways were slower to assert themselves.
I would agree that pushing the man from the bridge is more problematic than pulling the lever, not for reasons of responsibility or visceral abhorrence but simply because the mechanisms are not commensurate. We are being asked to compare unlikes. In my imagination, pulling the lever is clean and certain; pushing the fat guy is a bit of a gamble: he might struggle; he might twist in the air and land askew; he might bounce; he might not stop the trolley at all. I cannot calculate the efficacy of the splat with the same degree of certainty as I can the click of the point switch.
The probability of success, however, is factored into the MRI research carried out by Joshua Greene. You can read a fuller account of that research in the Harvard Magazine, here. And then you can decide whom to save and whom to spare.