Cristobal Unwin Holzapfel

Biological individuals have been at the centre of a series of persistent debates, both in philosophy and biology. Many of these discussions have developed under the assumption that biological individuals form a heterogenous kind of objects comprised by various interrelated sub-kinds, such as evolutionary and physiological individuals. In recent years, however, some works have started to question the overall status of this broad kind, including its explanatory capabilities and other seemingly defensible characteristics that earlier stages of the discussions had taken for granted. This paper follows that trail but starts from a slightly different point. I look at a series of contrasts, ambiguities, and foundational aspects of biological individuality to suggest that biological individuals are more fragmented than usually recognized.

In this work it is proposed that the conditions of identity for biological organisms are given by the following principle: for all organisms x and y, x = y if and only if x has been caused by the self-preserving activity of y. This principle determines both the inter-temporal identity of organisms and the identity of organism in different possible worlds. It unifies what can be supposed about conditions of identity coming from —at least— three different conceptions about the nature of biological organisms, those of RobertWilson, Thomas Pradeu and Ellen Clarke. These conceptions are presented and compared.

A significant and longstanding debate in philosophy of biology has centered around biological individuality. Although there have been numerous attempts to articulate a plausible and unifying view of what makes something a biological individual, the results are often conflicting and non-coextensive. In spite of these disputes, an open consensus around a few general ideas has surfaced (Pradeu 2016a). One common assumption that has been carried over with the consensus is that biological individuality is an intrinsic property of biological entities (Clarke 2016a). This tendency is reflected in the properties typically selected as criteria: what makes something an individual is quite often a property that biological entities themselves possess. I draw on Ellen Clarke’s (2013) evolutionary account of biological individuality, research about the evolution and maintenance of cooperation in the origins of multicellularity (Brockhurst et al. 2007; Gulli et al. 2019), and important parts of the consensus around biological individuality to argue against this trend. What makes something a biological individual is not always something about the entities in question. I show that there are environmental mechanisms capable of acting as individuation mechanisms in circumstances that resemble early transition stages, or in situations where individuality departs from paradigm cases. Therefore, biological individuality is not necessarily an intrinsic property.