"One must treat theory-in-use as both a psychological certainty and an intellectual hypothesis."

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One of the most basic and pervasive social processes is the sorting and labeling of things, activities, and people... Sorting and labeling processes involve a trade-off of costs and benefits. In general, the more finely the sorting is done, the greater the benefits - and the costs... Sorting and labeling, whether of people or of things, is a sorting and labeling of probabilities rather than of certainties.

— Thomas Sowell