The rise of mechanistic science in the seventeenth century helped give rise to a heated debate about whether teleology—the appearance of purposive activity in life and in mind—could be naturalized. At issue here were both what is meant by “teleology” as well as what is meant “nature”. I shall examine a specific episode in the history of this debate in the twentieth century with the rise of cybernetics: the science of seemingly “self-controlled” systems. Against cybernetics, Hans Jonas argued that cybernetics (...) failed as a naturalistic theory of teleology and that the reality of teleology is grounded in phenomenology, not in scientific explanations. I shall argue that Jonas was correct to criticize cybernetics but that contemporary work in biological organization succeeds where cybernetics failed. I will then turn to contemporary uses of Jonas’s phenomenology in enactivism and argue that Jonas’s phenomenology should be avoided by enactivism as a scientific research program, but that it remains open whether enactivism as a philosophy of nature should also avoid Jonas. (shrink)