Kevin Williamson has an interesting article on “One Way to Do Brexit: Unilateral Free Trade” (National Review, January 18, 2019). The fact that I wrote similar things, both on this blog (“Brits Could Have a Brexit Cake and Eat It Too”) and elsewhere (a recent example: my January 16 blog post “The Unbearable Lightness of Free Trade,” on the Law & Liberty website) does not take anything away from Williamson’s straight understanding and brilliant formulas--for example: The United Kingdom has...