I flew home to San Diego from visiting family in Baltimore last week. The view out my window over Houston, my connecting city, was crystal clear. The picture reminded me of my first plane ride late in my teenage years. How, I wondered at the time, did everything work together to create what, from the air, looked so harmonious? I had not the faintest idea. The question led me to study economics, first at Penn State and then at MIT, where I earned a doctorate after mastering, among other concepts, Adam Smith’s “invisible hand.” It explains the order I sought to understand. As I observed Houston from the air, my age now decades older, the importance of interstate roads was obvious. Without them, I’d see the minor roads jam-packed. The private airport we flew over could never handle the traffic at Houston’s IAH,…