Philosophers tend to approach the question ‘what is an individual?’ with two axiomatic assumptions: whatever else individuals might be, they are foremost particular things; and second, to say more than that we have to employ some theory of individuality, either a grand metaphysical theory, such as Aristotle’s hylomorphism, or a theory from a special science, such as Darwin’s theory of evolution by natural selection. A third assumption, that nature is divided into discrete individuals by a single set of ‘joints’, has also characterized much of the history of thought concerning individuality. This edited volume, whose authors include many of the world’s leading philosophers of science, marks a radical shift away from these intuitive dogmas of individuality. In place of an ontology of things, the authors describe a world populated by processes. Dispensing with theories of individuality, they urge a focus on acts of individuation in successful scientific practice. And in place of a natural world divided into wholly discrete individuals, we are shown a nature replete with ephemeral crosscutting joints and individuals that emerge only when processes of scientific investigation intersect the natural processes scientists track.
The view of individuality just sketched, which might be called pluralistic practice-based process ontology, is not presented as a univocal thesis, but rather emerges from a series of chapters on an eclectic array of natural objects—including stem cells, lichens, Drosophila, Bose-Einstein condensates, quasiparticles, holobionts, and a positron named ‘Priscilla’—along with articles on analytic metaphysics, environmental ethics, and the history of chemistry. I’ll offer a few words in defence of the traditional notion of individuality in closing, but I will begin with a brief summary of the chapters, which are organized into sections on metaphysics, experimental individuation, and realism.
John Dupré opens the section on metaphysics by defending a broadly Heraclitan process ontology, which trades philosophical questions about the nature of individuality for empirical questions about the way processes distinguish themselves from their surrounding causal flux. Dupré endorses a genidentical view of process individuality (that individuals are series of causes and effects) and he notes a number of biologically interesting ways genidentical lineages individuate themselves, including ‘organisms1’, which are segments of transgenerational evolutionary lineages, and ‘organisms2’, which are physiologically integrated multi-species lineage bundles. Considering variable configurations of fungi and photobionts in lichens, Dupré argues that empirically informed process ontology warrants taxonomic pluralism.
John Pemberton follows by arguing that all material objects and events, insofar as they are composed of moving subatomic particles, are processes composed of other processes. He then enumerates a taxonomy of criteria that scientists use to individuate the processes they study. Noting incongruence between the individuals identified in scientific practice and those thought to exist according to the ‘exemplar view’ in metaphysics, Pemberton petitions metaphysicians to deliver a concept of individuality more in line with the practice of science. This chapter does not consider accounts of individuality other than the exemplar view, but readers are likely to think of Dupré’s genidentical view as a possible answer to Pemberton’s call.
In the final chapter of the section on metaphysics, Marie Kaiser observes that individuality is often framed as a question about parts and wholes, and she offers a definition of the biological part-whole relation consisting of two necessary conditions: spatial inclusion and compositional relevance. Spatial inclusion means to be within a ‘natural boundary’ that reduces causal interactions between objects on opposite sides of the boundary. Compositional relevance means that a part must participate in some process that is characteristic of the biological whole. Kaiser presents her definition as monistic, but acknowledges that these two conditions are not always met. This suggests that pluralism is warranted, despite these two criteria defining the biological part-whole relation better than competing monistic theories.
The section on experimental individuation opens with a provocative chapter titled ‘Ask Not What Is an Individual’, in which Ken Waters crystalizes into a meta-philosophical imperative the anti-metaphysical theme running throughout much of this section. Recounting the history of genetics, Waters describes a succession of theoretical gene concepts, each failing to carve nature at its joints—there are just too many joints! Extending this argument to the debate about biological individuality, Waters observes a similar frustration with attempts to carve the world into ‘organisms’, ‘holobionts’, and ‘Darwinian individuals’, arguing that these concepts, like the concept of ‘gene,’ are tools for scientific investigation, not ontological categories of nature. Waters argues that we should abandon questions about the nature of individuality and replace them with more practical questions concerning the usefulness, purpose, and adequacy of the individuation concept.
In a chapter illustrating the link between experimental practice and individuality in stem cells, Melinda Fagan defends her view that colonies of cultured pluripotent stem cells are model organisms, analogous to lab mice and fruit flies, from an objection that stem cell colonies lack sufficient internal organization to qualify as organisms. When maintained as pluripotent cell lines, stem cells do not exhibit internal organization; but because they retain the potential to differentiate (in effect the potential to develop into multicellular organisms), stem cell colonies are organisms, just as the early developmental stages of animals are both organisms and clumps of stem cells. Fagan compares the practice of maintaining a pluripotent lineage via selection, transfer, and testing for continued pluripotency with the processes of natural selection and germ–soma separation, which divide natural lineages into generations of individuals.
Being one thing selected under a regimen of natural selection is frequently cited as a sufficient condition for biological individuality, so determining the levels at which selection operates is a perennial goal of biological metaphysics. Considering experimental approaches to the levels of selection question, James Griesemer argues that concepts of individuality are characterized by two kinds of process-relativity; individuals are simultaneously parts of natural processes operating in the world and parts of tracking processes imposed on the world by scientists. When designing experiments to measure differential selection and fitness, we cannot use the theoretical concept ‘unit of selection’ as a criterion for choosing which individuals to track, as that would result in circularity. However, the fitness of arbitrarily chosen individuals can be evaluated using a method called ‘contextual analysis’. Griesemer suggests that material overlap between generations offers yet another way to track reproduction, fitness, and individuality.
While Griesemer emphasizes the priority of experimental individuation over theories of individuality, Alan Love argues that, in some experimental contexts, theories of individuality are wholly superfluous. Love cites an experiment in developmental biology in which the size of a fly’s wing disk is tracked through development, and inferences about its relation to other developmental processes are drawn, without need or use of any theory of individuality. Love argues further that theories of individuality can impede scientific progress, as they tend to restrict the kinds of questions scientists ask and the processes they might choose to track. He acknowledges that genidentity is a theoretical concept ‘in the vicinity’ of the experimental practice he describes, but he nonetheless argues that no theory of individuality is required to conduct the experiment. In my view, readers would be right to think that a developing wing disk is indeed a genidentical, as is any other developmental process experimenters might choose to track.
In the final chapter of the second section, Ruey-Lin Chen distinguishes two modes of experimental individuation: an ontological mode of creation, and an epistemic mode of presentation. Experiments can either present the existence of natural individuals, or they can create individuals. Chen illustrates the first mode with experiments from condensed matter physics, in which Bose–Einstein condensates and fermion condensates are created, and he illustrates the second mode with an experiment from genetics, in which the identity of a gene for antibiotic resistance is presented. When individuals are created in an experiment, Chen calls this ontological experimental individuation. When experiments present naturally occurring individuals, Chen calls this epistemic experimental individuation.
Alexandre Guay and Olivier Sartenaer open the section on realism by considering the emergence of anyons—‘quasiparticle’ aggregations of electrons—which have been posited to explain the fractional quantum Hall effect, a pattern of impedance that is induced in steps as a conductor is exposed to a gradually intensifying electrical field. They first recount the emergence of anyons in the language of Gillett’s ‘strong emergence’, which posits a kind of determinative relation called ‘machresis’ to explain downward causation (that is, the motion of anyons being causally antecedent to that of the electrons from which they emerge). The authors reject downward causation as less than sober metaphysics, and offer in place of strong emergence a ‘transformational emergence’, emphasizing the temporal aspect of anyon formation. On the view presented, the electrical field transforms electrons into anyons, which are ontologically, rather than merely epistemically, new individuals.
Considering realism in particle physics more generally, Otávio Bueno examines three experiments that have trapped and manipulated atoms and subatomic particles, including one fascinating experiment in which researchers captured a single positron, held it for three months, and named it ‘Priscilla’. These experiments seem to demonstrate that atoms and sub-atomic particles are real individual objects, contra Schrödinger’s claim that quanta lack individuality and identity. A problem arises for particle realism, however, when attempting to verify that one is indeed tracking the same particle from t1 to t2, as quanta, according to theory, lack identity conditions. Bueno argues that measurements of trapped particles must be interpreted through the lens of quantum mechanical theory, and that claims of individuality rest on inference to the best explanation. He concludes that these experiments present strong evidence for the individuality of atoms and fundamental particles, but they nonetheless fail to establish with certainty their reality.
In a chapter focused on the reality of chemical kinds, Jonathon Hricko relates a history of competing theories of the ‘muriatic radical’ (the part of muriatic acid that distinguishes it from other acids), in order to motivate an amendment to ‘retail realism’, the idea that claims about realism are relative to particular theories. Working with different theories about the muriatic radical’s compositional nature, a number of early chemists were able to create and manipulate a single substance that they all called ‘muriatic radical’, even though one chemist thought the substance was oxygen, another hydrogen, and yet another chlorine. Hricko argues that theoretical entities can be individuated more or less inclusively, depending upon the number of theories in which they appear. When terms referring to theoretical entities appear in multiple theories, retail realists must specify which theory or set of theories they have in mind when they claim that some theoretical entity is real.
In the final chapter of this volume, Roberta Millstein defends Aldo Leopold’s view that ‘land communities’, composed of both biological populations and abiotic pools of resources, are individuals, and are therefore potential objects of moral consideration. Millstein notes an analogue of Waters’s ‘too many joints’ objection against individuating land communities: Ecologists divide nature into both communities of interacting organisms and ecosystems defined by steep gradients in energy and matter flow, but the elements that are included in each community or ecosystem are determined in part by the research questions scientists ask. Asking different questions leads to differently composed overlapping communities and ecosystems. Given the multiple decomposability of nature that arises in ecological practice, are there real land communities sufficiently individuated to be objects of moral consideration? Millstein argues that indeed there are, and that we must take into consideration both biotic interactions and gradients in the flow of abiotic resources when locating their boundaries.
It’s clear from some of these authors’ continued reliance on theories of individuality, and from the suggestion by others that fundamental particles appear to be things rather than processes, that the emerging view of practice-based process ontology sketched in the opening of this review has not been fully embraced, even in a volume dedicated to motivating it. While individuation in practice is well motivated in some scientific contexts, in others, such as when counting the members of a population, the scientific practice is to employ a theory of individuality, suggesting that these theories remain indispensable for science. Furthermore, the concept of individuality is widely applied outside of science—ranchers count heads of cattle, for example—so it would be myopic to insist that the concept must always be grounded in scientific practice. The arguments for conceiving of individuals as processes are compelling, but not to a degree that warrants abandoning substance ontology. Many properties can be ascribed to processes, but I don’t see a way to account for an individual’s mass within in a pure process ontology. Some synthesis of process and substance ontology, perhaps an ontology of materially continuous genidenticals (Molter ), could achieve the best of both worlds.
This book marks an important turn in scientific metaphysics and should be required reading for anyone hoping to make further advancements in the field. On Pemberton’s scale of graded individuality, from a loose bundle of sticks to a precision-tuned machine, this book is like a load of bent and gnarly logs bouncing down the road on the back of a truck. The chapters are heavy, as scholarly articles in metaphysics should be, and they are all moving in the same direction, but they only loosely hang together. Readers will notice very little overlap in the lists of references, indicating that the editors have succeeded in their effort to bring together a very broad spectrum of views. The eclectic range of topics, and the depths to which they are explored, will require of most readers at least some additional reading in the particular sciences in order to understand the arguments. These efforts will be rewarded with a novel set of perspectives on the way concepts of individuation and individuality are used in science.
Department of Philosophy
University of Utah
Molter, D. : ‘On Mushroom Individuality’, Philosophy of Science, 84, pp. 1117–27.