Skinner refers to the belief in free will as prescientific and the belief in determinism as scientific; neither belief can be proven, but environmental influences on behavior suggest that determinism is more likely. The defining characteristics of a good life are derived from value judgments based on feelings. Skinner declares this is a misstep, one which could be rectified through a scientific approach that would analyze the role of emotions and use its findings to improve the world.

Perception varies; paper may feel smooth after touching sandpaper or rough after touching glass. Skinner asserts that perceptions are relative to the individual: “What we attribute to an object when we call it red, rough, or sweet is in part a condition of our own body” (103). How a person feels about a certain perception is related to the perception’s reinforcing effect, and the reinforcing effects, in turn, impact behavior via operant conditioning. This process is integrated with evolution, as natural selection reinforces helpful behaviors and eliminates unbeneficial ones. External feelings, like touching something, and internal feelings, like depression, are similar, but external feelings are more active and developed through operant conditioning, while internal feelings are not.