Abstract: Various behavioral traits are said to be so well established that proponents of Libertarian Paternalism argue that the law should be altered to take account of their universal application. This lecture looks at three behavioral traits, each of which is commonly said to be very robust. Each is a form of aversion: inequity aversion, ambiguity aversion, loss aversion. It turns out that the evidence for these traits is very much more patchy than is commonly said to be the case. Adequate evidence for the kind of robustness that would be necessary to justify changing the law is altogether absent.