How shall we understand apparently teleological systems? What explains their persistence and their plasticity? Here I argue that all seemingly goal-directed systems—e.g., a food-seeking organism, human-made devices like thermostats and torpedoes, biological development, human goal seeking, and the evolutionary process itself—share a common organization. Specifically, they consist of an entity that moves within a larger containing structure, one that directs its behavior in a general way without precisely determining it. If so, then teleology lies within the domain of the theory (...) of compositional hierarchies. (shrink)