Abstract Attempts to define life have been uniformly unsuccessful, and this paper argues that no such definition is to be expected. However, it is important that life is not, as is still often assumed, a collection of discrete individual things, but rather a set of deeply intertwined processes. The paper provides three reasons for this view: that living systems are metabolic systems far from thermodynamic equilibrium; that they have characteristic life cycles, often passing through very different states; and that they are typically symbiotic, mutually interdependent with other systems. Recognition of this processual character of life makes clear why an adequate definition of life, a set of necessary and sufficient conditions for being alive, is unlikely to be forthcoming.
John Dupré (Wed,) studied this question.