… is from page 418 of the late University of Washington economist Paul Heyne ’s insightful 2000 paper “The Morality of Labor Unions,” as this paper is reprinted in the 2008 collection of Heyne’s writings, “Are Economists Basically Immoral?” and Other Essays on Economics, Ethics, and Religion  (Geoffrey Brennan and A.M.C. Waterman, eds.) (original emphasis):
Advocates of increased minimum legal wages often say that they would be perfectly willing to pay more for a burger or a cotton shirt in order to provide a living wage to the workers who produce burgers and cotton shirts. But would they go on purchasing as many burgers or cotton shirts as they formerly purchased? Even if they would, would everyone else do the same? A market system is a social system in which it is rarely possible to alter one variable without affecting others. Actions have unintended and unanticipated consequences.