Why Were Workers Whipped? Pain in a Principal-Agent Model

One reason a person hurts another is to get that person to do something. This paper uses a model to show that threatening pain can be rational and that pain is inflicted upon people who are poor in the sense of having bad alternatives. The model corrects a confusion in previous models of slavery; gives an explanation of why child, and not adult, laborers were beaten during the industrial revolution; and prompts a discussion of the dangers of rational-choice modeling.