Kill the pedestrian or the passenger? The complicated ethics of self-driving cars.

Imagine this scenario: You're driving down the road when suddenly, out of nowhere, a lone pedestrian jumps into your path. The road is narrow and walled in by a barrier on either side, so your options are limited. You can either keep driving straight ahead and hit the pedestrian, or you can save the pedestrian by swerving into one of the barriers. Now imagine a scenario in which it's five pedestrians in the road instead of one. In the real world, rare though such scenarios might be, the driver would likely be forced to make a split-second decision about how to behave -- a choice that he or she probably wouldn't even have time to fully think through.