From The Ethics of Eating Animals, p. 317

To visit a modern Concentrated Animal Feeding Operation (CAFO) is to enter a world that for all its technological sophistication is still designed on seventeenth-century Cartesian principles: Animals are treated as machines–“production units”–incapable of feeling pain. Since no thinking person can possibly believe this anymore, industrial animal agriculture depends on a suspension of disbelief on the part of the people who operate it and a willingness to avert one’s eyes on the part of everyone else.