Abstract: In contemporary science, causal explanation usually means proximate causal explanation. However, teleological explanation or explanation by “ultimate cause” still plays a role, especially in such disciplines as evolutionary biology or social sciences. Yet, philosophically, there is a question about whether teleological explanations, though useful on occasions, are legitimate scientific explanations, or whether they can eventually be replaced by proximate causal explanations. We believe teleological explanations are bona fide legitimate explanations because they are a form of the “extremum principles” – principles of minimum or of maximum. We argue that not only are such explanations legitimate in biological and social sciences, but in fact they are intrinsic to all of sciences, including quantum mechanics and relativity theories.

Key Words: Scientific explanation; Stationary-action principle; Law of entropy increase; Evolutionary game theory; Replicator equation; Predictive processing, Free energy principle