… is from page 227 of Thomas Sowell’s magnificent 1980 volume, Knowledge and Decisions (original emphasis):
When all else fails, believers in this vision [of market economies as systems of exploitation] point to specific activities by capitalist nations that have behaved in ways that are regarded as morally wrong. Whatever the merits of their arguments in particular cases, the abuse of power is too universal an historical phenomenon to be made a defining characteristic of capitalism. It seems especially inappropriate as part of an argument for alternative systems with more concentration of power.
