Tariffs aren't new—neither is the misguided notion of "reciprocal" ones. Milton Friedman cut through this fallacy with clarity: When other nations restrict trade, they harm their own citizens. When we respond with our own tariffs, we merely punish our citizens, too. After all, you don't fix holes in the bottom of the boat by shooting more holes in it. Free trade benefits America regardless of what other countries do. Refusing to buy something at the best price available is simply bad business.

What happens if economic policy incentivizes the Scottish to produce more wine and fewer sheep? Everyone gets less wine, less haggis, and higher prices. Andrew Heaton explains.