This note is inspired by DG Lesvic’s objection to Art Carden’s use of the reductio ad absurdum in a comment to this earlier post  – an objection that, I confess, I do not share.
Reductios work so well when arguing against proponents of economic nationalism (that is, “protectionists”) because, economically and morally speaking, there is absolutely no difference between Suzy trading with Joe her next-door neighbor and Suzy trading with Jose in Mexico, Josef in Austria, or Javu in China. None.
So when any protectionist argues, based on reason X, for restrictions on trade drawn along national political borders, it’s always enlightening to apply the same argument X to trade restrictions drawn more locally – even as locally as the individual.
Fritz Machlup said in class at NYU back in 1981 that arguments for protectionism, when followed through to their logical conclusion, always ‘prove’ that a person’s right hand should not trade with that person’s left hand.