… is from page 491 of the 5th edition (2015) of Thomas Sowell’s Basic Economics :
International trade restrictions provide yet another example of the fallacy of composition, the belief that what is true for a part is true for the whole.
DBx: Yep. A politician or a professor sees an industry or a town in economic decline today because of free trade, he or she concludes that the entire economy must therefore be in economic decline because of free trade or that this industry or town will remain in decline into the future because of free trade. The conclusion is fallacious. Yet it is powerful fuel for demagogues whose lust for power is gratified by stoking fears that are sparked by this fallacy.