Origin of Life and Evolution of Biospheres in press 2006

DEFINITELY LIFE BUT NOT DEFINITIVELY

Joan Oliver ¹ and Randall S. Perry^{1, 2}

¹Planetary Science Institute, Seattle WA, 98115

²IARC, Department of Earth Science and Engineering, South Kensington Campus Imperial College London, SW7 2AZ

Correspondence: joanoliver@lunarloft.freeserve.co.uk or perry@psi.edu

Key words: definition of life, definitions, living systems, living entities, working descriptions, what is life, origin of life, life, lexicology, astrobiology, science definitions

Abstract

Although there have been attempts at a definition of life from many disciplines, none is accepted by all as definitive. Some people believe that it is impossible to define ‘life’ adequately at the moment. We agree with this point of view on linguistic grounds, examining the different types of definition, the contexts in which they are used and their relative usefulness as aids to arriving at a scientific definition of life. We look at some of the more recent definitions and analyse them in the light of our criteria for a good definition. We argue that since there are so many linguistic and philosophical difficulties with such a definition of life, what is needed is a series of working descriptions, which are suited to the audience and context in which they are used and useful for the intended purpose. We provide some ideas and examples of the forms these may take.