Species in three and four dimensions

Abstract

There is an interesting parallel between two debates in different domains of contemporary analytic philosophy. One is the endurantism-perdurantism, or threedimensionalism vs. four-dimensionalism, debate in analytic metaphysics. The other is the debate on the species problem in philosophy of biology. In this paper I attempt to cross-fertilize these debates with the aim of exploiting some of the potential that the two debates have to advance each other. I address two issues. First, I explore what the case of species implies regarding the feasibility of particular positions in the endurantismperdurantism debate. I argue that the case of species casts doubt on the recent claim that three-dimensionalism and four-dimensionalism are equivalent descriptions of the same underlying reality. Second, and conversely, I examine whether the metaphysical worry about three-dimensionalism and four-dimensionalism can help us to better understand the nature of biological species. I show that analyzing the thesis that species are individuals against the background of the endurantism-perdurantism debate allows us to explicate two different ways in which this thesis can be interpreted.

The Ethics of Animal Re-creation and Modification

“…Following the literature on the subject (Okasha 2002;Stamos 2003;Reydon 2008), it is possible to distinguish at least two types of class depending on the nature of the property defining the characteristics of membership: the members of a given class possess a real essence; and the members of the class exhibit a relational essence with no necessary property, only some sufficient ones. On the other hand, it is now current to distinguish two concepts of individuality relative to change and time metaphysics: vertical and horizontal in biological terms or presentist/eternalist in metaphysical terms.…”

“…An endurantist must reply negatively to the question whether the boat still is Theseus's boat, because all the parts of the boat are not present at the same time in the spatial form designating the boat. According to the perdurantisteternalist approach, the boat still is the same boat, even though all of its parts have been replaced, because it remains the same space-time worm understood as a mereological sum of temporal parts (Reydon 2008).…”

“…Its constitutive weakness is its lack of intuitive appeal and the confusing debates it provokes among philosophers of biology. Reydon (2008), for instance, proposes two distinct denotations for the term 'species': as events and as objects. Only the second is considered in a four-dimensional space-time.…”

Species and kinds: a critique of Rieppel’s “one of a kind” account of species

“…In this formulation, two common ways of conceiving of individuals—as causally integrated systems or as historical entities—seem to be conflated. (A recent extensive discussion of these different ways of thinking about individuality, paying specific attention to the case of species, can be found in Reydon, 2008). On the former view, a species is thought of as a spatially (but not temporally) extended population or metapopulation, that is, as a population‐level system of organisms that are parts of the system because they stand in causal relations with other parts (organisms) of the system.…”

“…As this is precisely the case for species, on Rieppel’s view species‐as‐individuals are conceived of as historical individuals. (The distinction between the two kinds of individual is often framed metaphysically as a distinction between three‐dimensional objects that extend in the three spatial dimensions, and four‐dimensional objects that also extend in the temporal dimension; see Reydon, 2008 for details. )…”