The problem of biological individuality

This paper examines six contemporary philosophical theories of the problem of biological individuality, namely, (i) Peter Godfrey-Smith's Darwinian approach, (ii) Alvaro Moreno and Matteo Mossio's functional-organizational view, (iii) Fermín Fulda's agency-based account, (iv) the processual view associated with Anne Sophie Meincke, (v) John Maynard Smith and Eörs Szathmáry's evolutionary transitions theory, and (vi) Anderson Fonseca's gradualist protopsychic monism. Each theory is reconstructed with attention to the reasoning that sustains it and confronted with real biological entities, such as transposons, holobionts, trees, octopuses, and bryozoan colonies, at least some of which are misclassified by one of the theories. For each objection, we ask whether it allows for an internal fix or is fatal to the theory, showing that the available patches either cost conceptual precision, or reintroduce the assumptions the original formulation sought to avoid. It also discusses the impossibility of grounding biological individuality in chemistry or physics, given the categorical incompatibility between the typological vocabulary of those sciences and the historical vocabulary of biology. The conclusion is that none of the theories examined solves the problem of biological individuation, since each one, by choosing a single criterion for individuality, always leaves some real biological entity misclassified, suggesting that biological individuality is a phenomenon recalcitrant to any single, definitive criterion.