We see this problem in many places: in the difficulty of managing overfishing, or in reducing carbon emissions to mitigate climate change. When it comes to the regulation of driverless cars, the common land now is basically public safety — that's the common good — and the farmers are the passengers or the car owners who are choosing to ride in those cars. And by making the individually rational choice of prioritizing their own safety, they may collectively be diminishing the common good, which is minimizing total harm. It's called the tragedy of the commons, traditionally, but I think in the case of driverless cars, the problem may be a little bit more insidious because there is not necessarily an individual human being making those decisions. So car manufacturers may simply program cars that will maximize safety for their clients, and those cars may learn automatically on their own that doing so requires slightly increasing risk for pedestrians. So to use the sheep metaphor, it's like we now have electric sheep that have a mind of their own.