All purposeful interpretations of behavior count on some idea of what is good and bad. If we are conversing in periods of evolutionary adaptation, good and awful boil down to standards of inclusive Darwinian fitness, a measure sensibly clear in standard, but often vague in practice. If we are conversing in periods of the operant behavior of one-by-one animals, good and awful correspond to pay and penalty, to positions better or poorer than the present situation. This section is about pay and punishment: about the notion of reinforcement that encompasses them both, about how it is characterised, and the methods utilised ...