Variational rationality: finding cheap and quick enough ways of motion to satisfice our recurrent and changing needs/desires

As physics provides the equations of motion of a body, this paper formulates, for the first time, at the conceptual/mathematical levels, the inequations of motion of an individual seeking to meet his needs/desires in an adaptive/flexible way. Successful (failed) dynamics perform a succession of moves that are, at once, satisficing (improving enough) and worthwhile (free from too many sacrifices), or not. They approach or reach needs and desires (fall into traps). They balance the desired speed of approach to a desired end (a distal promotion goal) with the size of the required immediate sacrifices to go fast (a proximal prevention goal). Therefore, each period, need/desire satisfaction success requires enough self-control to be able to make, in the long run, sufficient progress in need/desire satisfaction without enduring, in the short run, too many sacrifices. A simple example (lose or gain weight) shows that the size of successful moves must be neither too small nor too long. The appendix solves this problem, using an approximate gradient algorithm. This paper opens the door to "algorithmic psychology" which generalizes and models the famous Lewin's "topological psychology" using the recent variationality approach of stay/change human dynamics.