Defining ‘Life’
Abstract
There is no broadly accepted definition of 'life.' Suggested definitions face problems, often in the form of robust counter-examples. Here we use insights from philosophical investigations into language to argue that defining 'life' currently poses a dilemma analogous to that faced by those hoping to define 'water' before the existence of molecular theory. In the absence of an analogous theory of the nature of living systems, interminable controversy over the definition of life is inescapable.
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Without additional examples of life, it is impossible to know whether the concept of life describes an objective natural phenomenon or a subjective category that cannot be perfectly defined.
“Cleland and Chyba (2002) were the first to argue that, without additional examples of life and the greater understanding they may provide, it is even impossible to know whether the concept of life describes an objective natural phenomenon or a subjective category that cannot be perfectly defined (Cleland and Chyba, 2002; Robus et al., 2009).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Cleland and Chyba, 2002
Critics of the NASA/Joyce definition find the stipulation of Darwinian evolution overly specific.
“Critics of the definition find that the stipulation of Darwinian evolution is overly specific (Cleland and Chyba, 2002).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Cleland and Chyba, 2002
The Joyce (1994) definition gives a useful way to identify candidate life-forms but requires that the life-form be verified by clear evidence of evolution.
“But while the Joyce (1994) definition gives us a useful way to identify candidate life-forms, it also requires that the life-form be verified by no less than clear evidence of evolution (Luisi, 1998; Cleland and Chyba, 2002).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Cleland and Chyba, 2002
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References 21 · Cited by 347
- Authors
- Cleland, C. E., & Chyba, C. F.
- Affiliations
- University of Colorado Boulder (US)
- Search for Extraterrestrial Intelligence (US)
- Venue
- Origins of life and evolution of the biosphere
- Published
- 2002-08
- Volume
- 32
- Issue
- 4
- Pages
- 387-393
- ISSN
- 0169-6149 (ISSN-L)
- 1573-0875
- OpenAlex
- W3191793628
- Cited by
- 347
- References
- 21
- Citations by year
- 2026: 10 · 2025: 21 · 2024: 13 · 2023: 12 · 2022: 16 · 2021: 21 · 2020: 38 · 2019: 29 · 2018: 16 · 2017: 12 · 2016: 17 · 2015: 12 · 2014: 9 · 2013: 14 · 2012: 12
- FWCI
- 2.32
- Type
- journal article
- Language
- en
- Open access
- closed
- Licence
- Locations
- Origins of Life and Evolution of Biospheres (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Aeronautics and Space Administration
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Origins and Evolution of Life
- Social Sciences › Arts and Humanities › History and Philosophy of Science › Philosophy and History of Science
- Social Sciences › Arts and Humanities › Philosophy › Philosophical and Cultural Analysis
- Keywords
- concept of life, philosophy of language, water problems, counterexample, molecular theory, origin of life
- MeSH terms
- Origin of Life, Extraterrestrial Environment, Philosophy, Water, Exobiology, Life, Evolution, Chemical
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