¹Physicist Murray Gell-Mann, the Nobel laureate who conceived the quark, famously explained the difficulty to his colleagues: “Imagine how hard physics would be if electrons could think.” Given the limitations economists face in performing experiments, perhaps an even better question would have been “imagine how hard experimental physics would be if electrons had human rights.” (Gell-Mann is also credited with saying that, compared with economics, the “hard” sciences are easy.)