Abstract

The question What is an individual? goes back beyond Aristotle’s discussion of substance to the Ionians’ preoccupation with the paradox of change -- the fact that if anything changes it must stay the same. Mere reflection on this fact and the common-sense notion of a countable thing yields a concept of a “minimal individual”, which is particular (a logical matter) specific (a taxonomic matter), and unique (an evaluative empirical matter). Individuals occupy space, and therefore might be dislodged. Even minimal individuals, therefore (Strawsonian individual or Aristotelian substance) already contain the potential for competition or conflict. What is added by biology to this basic notion? It emerges from some recent work on the evolution of metazoan animals that individuals as we know them are minimal individuals towhich four features have been added, and which appear to be inseparable: differentiated multicellularity; sexual reproduction; segregation of germ from somatic cells; and obligatory death. Whether or not individuals are to be counted as units of selection, they are not the beneficiaries of natural selection.