Nicholas Carr wonders how long it will be before machines need to have ethical systems built in. Imagine, he says, that you’re happily tweeting away as your Google self-driving car crosses a bridge, its speed precisely synced to the 50 m.p.h. limit. A group of frisky schoolchildren is also heading across the bridge, on the pedestrian walkway. Suddenly, there’s a tussle, and three of the kids are pushed into the road, right in your vehicle’s path. Your self-driving car has a fraction of a second to make a choice: Either it swerves off the bridge, possibly killing you, or it runs over the children. What does the Google algorithm tell it to do?”