Never underestimate fear of financial loss as a motivator. Last week in this column, I argued that the threat to place tariffs on Mexican goods was a bad idea because there are less risky and destructive ways to deal with the immigration problem on the U.S. southern...

For more than two centuries, economists and well-read people have understood that tariffs reduce the levels of competitiveness and prosperity. Adam Smith (1723-1790) explained how free trade (by increasing the extent of the market) enabled greater specialization and...