Framing Human Action in Physics: Valid Reconstruction, Invalid Reduction

We propose framing human action in physics before reaching to biology and social sciences, rearranging the order of their usual deployment. As an example, consider efforts to model altruism that start in a frame of psychological or social attributes such as reciprocity, empathy, and identity. Evolutionary roots might also be used by appeal to survival of the species from biology. Only then the modeler abstracts to work on notations, and to establish relationships using mathematical apparatus from physics. This top-down deployment of principles from various scientific disciplines has generated a body of coherent models, partially generalizable theories, and disagreements. In this paper we present a definition of action as a movement between two points in the relevant space, and explore reversing the direction of deploying scientific theories, starting with the principle of least action in physics to frame observed human action. Used as an organizing principle of the whole universe, optimization element in human behavior does not have to be presumed to arise from animate aspects of adaptive and cognitive faculties; emergence of social phenomena, when optimal, can be disconnected from methodological individualism. Our three-tier framework makes room for physical, biological and social science principles, proposing a new perspective on human behavior, sans reductionism.