ABSTRACT
Our aim is to generalize certain methods used in the study of dynamical systems to living systems whose behaviors express the intentional selection of goals. Goal-directed movements are as commonplace as any other form of motion studied by science, yet we seem to know so much less about them. But there is no reason to assume that dynamical principles apply only to the aimless behavior of nonliving systems. If nature is truly economical, then the shared evolutionary lineage of living systems with their near inanimate prototypes (e.g., viruses and DNA) makes likely a continuing reign of dynamical principles common both to physical laws and biological constraints.
