Here’s a letter to The American Conservative (HT Craig Kohtz):
Pat Buchanan repeats his familiar litany against free trade and immigration (“Whose Country Is It, Anyway? ” Sept. 19). That litany boils down to a simple formula: the U.S. economy declines as American consumers gain better access to lower-priced goods and services, and as American producers gain better access to lower-cost means of production.
In short, competition creates poverty, while monopoly creates wealth.
Economists  have repeatedly and utterly debunked such claims for the alleged marvels of monopoly power. I’ll not here repeat any such debunking. Instead, I merely highlight one internal inconsistency in Mr. Buchanan’s own arguments.
He frequently asserts that 19th-century America’s policy of relatively high tariffs, along with its impressive economic growth, proves that protectionism promotes prosperity . End of story; full stop; no further analysis is necessary. Fact A’s simultaneous existence with fact B proves that A caused B.
Well, 19th-century America also had open immigration. So Mr. Buchanan ought to join the ranks of those of us who support a return to that policy. After all, according to the tenets of his own epistemology, the mere fact that booming 19th-century America had open immigration proves that open immigration promotes – or at least doesn’t hamper – vibrant economic growth.
Donald J. Boudreaux
UPDATE: And, in fact, the evidence does seem to indicate that open immigration – unlike protectionism – played a significant role in promoting economic growth in the latter half of 19th-century America .