… is from page 84 of Paul Krugman’s vital 1996 Pop Internationalism; specifically, it’s from Krugman’s 1995 essay “The Illusion of Conflict in International Trade”:
I believe that if the rhetoric that portrays international trade as a struggle continues to dominate the discourse, then policy debate will in the end be dominated by men like [protectionist author of The Trap, Sir James] Goldsmith, who are willing to take that rhetoric to its logical conclusion. That is, trade will be treated as war, and the current system of relatively open world markets will disintegrate because nobody but a few professors believes in the ideology of free trade.
And that will be a shame, because for all their faults the professors are right. The conflict among nations that so many policy intellectuals imagine prevails is an illusion; but it is an illusion that can destroy the reality of mutual gains from trade.