Vanessa Triviño

The debate in Metaphysics of Science concerning the interaction between metaphysics and science has been mainly approached from the perspective of the scientific discipline of physics. In this paper, I address this debate from a different framework, namely that of biology. I pay attention to the recent characterization of Metaphysics of Biology and the different forms in which philosophers use metaphysics when addressing conceptual biological problems. In doing so, I argue that two main lessons can be obtained that can serve to enrich the debate in Metaphysics of Science: i) that the interaction between metaphysics and science seems to be more complex than generally considered; and ii) that the type of metaphysics that is interacting with science when characterizing the ontological status of the world is neither the a priori nor the naturalized one, but a different form of metaphysics that will be labelled here as applied metaphysics.

Since the last decades of the twentieth and the beginning of the twenty-first century, the use of metaphysics by philosophers when approaching conceptual problems in biology has increased. Some philosophers call this tendency in philosophy of biology ‘Metaphysics of Biology’. In this paper, I aim at characterizing Metaphysics of Biology by paying attention to the diverse ways philosophers use metaphysics when addressing conceptual problems in biology. I will claim that there are two different modes of doing Metaphysics of Biology, namely Metaphysics for Biology and Metaphysics in Biology.

Holobionts are symbiotic assemblages composed by a host plus its microbiome. The status of holobionts as individuals has recently been a subject of continuous controversy, which has given rise to two main positions: on the one hand, holobiont advocates argue that holobionts are biological individuals; on the other, holobiont detractors argue that they are just mere chimeras or ecological communities, but not individuals. Both parties in the dispute develop their arguments from the framework of the philosophy of biology, in terms of what it takes for a “conglomerate” to be considered an interesting individual from a biological point of view. However, the debates about holobiont individuality have important ontological implications that have remained vaguely explored from a metaphysical framework. The purpose of this paper is to cover that gap by presenting a metaphysical approach to holobionts individuality. Drawing upon a conception of natural selection that puts the focus on the transgenerational recurrence of the traits and that supports the thesis that holobionts are units of selection, we argue that holobionts bear emergent traits and exert downward powers over the entities that compose them. In this vein, we argue, a reasonable argument can be made for conceiving holobionts as emergent biological individuals.

Holobionts are symbiotic assemblages composed by a macrobe host plus its symbiotic microbiota. In recent years, the ontological status of holobionts has created a great amount of controversy among philosophers and biologists: are holobionts biological individuals or are they rather ecological communities of independent individuals that interact together? Chiu and Eberl have recently developed an eco-immunity account of the holobiont wherein holobionts are neither biological individuals nor ecological communities, but hybrids between a host and its microbiota. According to their account, the microbiota is not a proper part of the holobiont. Yet, it should be regarded as a set of scaffolds that support the individuality of the host. In this paper, we approach Chiu and Eberl’s account from a metaphysical perspective and argue that, contrary to what the authors claim, the eco-immunity account entails that the microorganisms that compose the host’s microbiota are proper parts of the holobiont. Second, we argue that by claiming that holobionts are hybrids, and therefore, not biological individuals, the authors seem to be assuming a controversial position about the ontology of hybrids, which are conventionally characterized as a type of biological individual. In doing so, our paper aligns with the contemporary tendency to incorporate metaphysical resources to shed light on current biological debates and builds on that to provide additional support to the consideration of holobionts as biological individuals from an eco-immunity perspective.

The notion of fitness is usually equated to reproductive success. However, this actualist approach presents some difficulties, mainly the explanatory circularity problem, which have lead philosophers of biology to offer alternative definitions in which fitness and reproductive success are distinguished. In this paper, we argue that none of these alternatives is satisfactory and, inspired by Mumford and Anjum’s dispositional theory of causation, we offer a definition of fitness as a causal dispositional property. We argue that, under this framework, the distinctiveness that biologists usually attribute to fitness—namely, the fact that fitness is something different from both the physical traits of an organism and the number of offspring it leaves—can be explained, and the main problems associated with the concept of fitness can be solved. Firstly, we introduce Mumford and Anjum's dispositional theory of causation and present our definition of fitness as a causal disposition. We explain in detail each of the elements involved in our definition, namely: the relationship between fitness and the functional dispositions that compose it, the emergent character of fitness, and the context-sensitivity of fitness. Finally, we explain how fitness and realized fitness, as well as expected and realized fitness are distinguished in our approach to fitness as a causal disposition.

Contemporary biological research has suggested that some host–microbiome multispecies systems (referred to as “holobionts”) can in certain circumstances evolve as unique biological individual, thus being a unit of selection in evolution. If this is so, then it is arguably the case that some biological adaptations have evolved at the level of the multispecies system, what we call hologenomic adaptations. However, no research has yet been devoted to investigating their nature, or how these adaptations can be distinguished from adaptations at the species-level (genomic adaptations). In this paper, we cover this gap by investigating the nature of hologenomic adaptations. By drawing on the case of the evolution of sanguivory diet in vampire bats, we argue that a trait constitutes a hologenomic adaptation when its evolution can only be explained if the holobiont is considered the biological individual that manifests this adaptation, while the bacterial taxa that bear the trait are only opportunistic beneficiaries of it. We then use the philosophical notions of emergence and inter-identity to explain the nature of this form of individuality and argue why it is special of holobionts. Overall, our paper illustrates how the use of philosophical concepts can illuminate scientific discussions, in the trend of what has recently been called metaphysics of biology.

Resumo Neste artigo, vamos considerar o recente debate na metafísica da evolução, no que diz respeito tanto à persistência como à “mudança” em espécies biológicas, segundo a tese que considera a espécie como o agregado de indivíduos. Centrar-nos-emos na proposta de Thomas Reydon, que argumenta que em biologia, o termo “espécie” refere-se a duas entidades biológicas, por si denominadas evolverons e phylons, que desempenham vários papéis epistemológicos em pelo menos duas disciplinas diferentes, nomeadamente na biologia sistemática e na biologia evolutiva. Em particular, analisamos criticamente a alegação de Reydon, que estas duas entidades biológicas geraram um problema para a tese que sustém a equivalência entre duas teorias de persistência, desenvolvidas pela metafísica analítica contemporânea: o tri–Dimensionalismo e tetra–Dimensionalismo. Neste artigo, pretende-se restaurar a tese da equivalência metafísica, recorrendo a uma tripla estratégia: promover a ideia de que os evolverons e os “phylons” são duas dimensões de uma mesma realidade; recorrer a uma noção menos problemática noção de endurantismo e, por último, destacar alguns problemas que surgem dos exemplos biológicos empregues por Reydon para basear o desenvolvimento dos seus argumentos. Palavras-chave : conceito de espécie, endurantismo, equivalência metafísica entre 3D e 4D, espécies biológicas sincrónicas e diacrónicas, persistênciaIn this paper we revise a recent debate on the metaphysics of evolution pertaining to both the persistence and change of biological species, and the species-as-individuals thesis. We focus on Thomas Reydon’s proposal that, in biology, the term “species” refers to two different biological entities, which he calls evolverons and phylons, and plays different epistemological roles in at least two different disciplines in which it is used, namely, evolutionary and systematic biology. In particular, we critically revise Reydon’s claim that these two biological entities raise a problem for the thesis of the equivalence between the two theories of persistence developed in contemporary analytic metaphysics: three–dimensionalism and four–dimensionalism. In this paper, we aim to reinstate the thesis of metaphysical equivalence by a threefold strategy: motivation of the idea that evolverons and phylons are two dimensions of the same entity, shifting to a less problematic notion of endurance, and an exploration of doubts about the particular biological examples upon which Reydon bases his arguments. Keywords : 3D / 4D metaphysical equivalence, endurantism, persistence, species concept, synchronic and diachronic biological species