Abstract
Part of the art of theory building is to construct effective basic concepts, with a large reach and yet powerful as tools for getting at conclusions. The most basic concept of population biology is that of individual. An appropriately reengineered form of this concept has become the basis for the theories of structured populations and adaptive dynamics. By appropriately delimiting individuals, followed by defining their states as well as their environment, it become possible to construct the general population equations that were introduced and studied by Odo Diekmann and his collaborators. In this essay I argue for taking the properties that led to these successes as the defining characteristics of the concept of individual, delegating the properties classically invoked by philosophers to the secondary role of possible empirical indicators for the presence of those characteristics. The essay starts with putting in place as rule for effective concept engineering that one should go for relations that can be used as basis for deductive structure building rather than for perceived ontological essence. By analysing how we want to use it in the mathematical arguments I then build up a concept of individual, first for use in population dynamical considerations and then for use in evolutionary ones. These two concepts do not coincide, and neither do they on all occasions agree with common intuition-based usage.
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Acknowledgments
The present note got of the ground in a workshop on Evolutionary and Ecological Individuals, organised by Philippe Huneman and Minus van Baalen in the context of the multidisciplinary project Ecology and Philosophy: Individuality, Stability & Ethics, funded by the research program “Ingénierie Ecologique” of the CNRS Institut National Ecologie et Environnement. This work benefitted from the support from the “Chaire Modélelisation Mathématique et Biodiversité of Veolia Environnement- Ecole Polytechnique - Museum National d’Histoire Naturelle - Fondation X”.
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Metz, J.A.J. On the concept of individual in ecology and evolution. J. Math. Biol. 66, 635–647 (2013). https://doi.org/10.1007/s00285-012-0610-1
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DOI: https://doi.org/10.1007/s00285-012-0610-1