Biological Theory

, Volume 13, Issue 2, pp 76–92 | Cite as

Life as Adaptive Capacity: Bringing New Life to an Old Debate

  • Kelly C. SmithEmail author
Thematic Issue Article: Astrobiology


Whatever we take “life” to mean, it must involve an attempt to describe the objective reality beyond scientists’ biases. Traditionally, this is thought to involve comparing our scientific categories to “natural kinds.” But this approach has been tainted with an implicit metaphysics, inherited from Aristotle, that does not fit biological reality. In particular, we must accept that biological categories will never be specifiable in terms of necessary and sufficient conditions or shared underlying physical structures that produce clean boundaries. Biology blurs all lines and failure to embrace this unique feature has blocked attempts to reach consensus on the meaning of “life.” Thus, while the three classical accounts (thermodynamic, metabolic, and evolutionary) all fall short of offering a complete definition, their advocates fail to realize that they share the same view of life’s ultimate, functional hallmark: its uniquely rich adaptive capacity. I develop an account of life as adaptive capacity that sidesteps debates about the relative importance of specific mechanisms and the precise location of boundaries to bring the three classical accounts together under a shared conceptual framework.


Adaptation Aristotle Complexity Definition Life Natural kind 



The ideas in this article were inspired by numerous conversations with too many colleagues to mention. However, extensive comments provided on an earlier draft by Carlos Mariscal and Erik Persson were especially helpful. Any deficiencies that remain are, of course, entirely the fault of the author.


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Copyright information

© Konrad Lorenz Institute for Evolution and Cognition Research 2018

Authors and Affiliations

  1. 1.Department of Philosophy and ReligionClemson UniversityClemsonUSA

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