By William M. Arkin, from Unmanned: Drones, Data, and the Illusion of Perfect Warfare, out next month from Little, Brown. Arkin is a former army intelligence analyst and the author of several books on U.S. military and intelligence affairs, including Top Secret America.

If you have spent any time thinking about the exponential increase in the use of unmanned vehicles over the past decade, you have probably thought about the Predator drone. Every second of every day, about fifty Predators are airborne. Each weighs more than a ton and has wings that extend the length of four automobiles. They…