Abstract
This paper discusses similarities between the mathematization of operant behavior and the early history of the most mathematical of sciences-physics. Galileo explored the properties of motion without dealing with the causes of motion, focusing on changes in motion. Newton's dynamics were concerned with the action of forces as causes of change. Skinner's rationale for using rate to describe behavior derived from an interest in changes in rate. Reinforcement has played the role of force in the dynamics of behavior. Behavioral momentum and maximization have received mathematical formulations in behavior analysis. Yet to be worked out are the relations between molar and molecular formulations of behavioral theory.