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. (shrink)

My topic is personal identity, or rather,ouridentity. There is general, but not, of course, unanimous, agreement that it is wrong to give an account of what is involved in, and essential to, our persistence over time which requires the existence of immaterial entities, but, it seems to me, there is no consensus about how, within, what might be called this naturalistic framework, we should best procede. This lack of consensus, no doubt, reflects the difficulty, which must strike anyone who has (...) considered the issue, of achieving, just in one's own thinking, a reflective equilibrium. The theory of personal identity, I feel, provides a curious contrast. On the one side, it seems highly important to know what sort of thing we are, but, on the other, it is hard to find any answer which has a ‘solid’ feel. (shrink)

From the time of Locke, discussions of personal identity have often ignored the question of our basic metaphysical nature: whether we human people are biological organisms, spatial or temporal parts of organisms, bundles of perceptions, or what have you. The result of this neglect has been centuries of wild proposals and clashing intuitions. What Are We? is the first general study of this important question. It beings by explaining what the question means and how it differs from others, such as (...) questions of personal identity and the mind-body problem. It then examines in some depth the main possible accounts of our metaphysical nature, detailing both their theoretical virtues and the often grave difficulties they face. The book does not endorse any particular account of what we are, but argues that the matter turns on more general issues in the ontology of material things. If composition is universal--if any material things whatever make up something bigger--then we are temporal parts of organisms. If things never compose anything bigger, so that there are only mereological simples, then we too are simples--perhaps the immaterial substances of Descartes--or else we do not exist at all (a view Olson takes very seriously). The intermediate view that some things compose bigger things and others do not leads almost inevitably to the conclusion that we are organisms. So we can discover what we are by working out when composition occurs. (shrink)

Darwin’s classic ‘Origin of Species’ (Darwin 1859) described forces of selection acting upon individuals, but there remains a great deal of controversy about what exactly the status and definition of a biological individual is. Recently some authors have argued that the individual is dispensable – that an inability to pin it down is not problematic because little rests on it anyway. The aim of this paper is to show that there is a real problem of biological individuality, and an urgent (...) need to arbitrate over the current plethora of solutions to it. (shrink)

Biological theory demands a clear organism concept, but at present biologists cannot agree on one. They know that counting particular units, and not counting others, allows them to generate explanatory and predictive descriptions of evolutionary processes. Yet they lack a unified theory telling them which units to count. In this paper, I offer a novel account of biological individuality, which reconciles conflicting definitions of ‘organism’ by interpreting them as describing alternative realisers of a common functional role, and then defines individual (...) organisms as essentially possessing some mechanisms that play this role. (shrink)

In dicephalus conjoined twinning, it appears that two heads share a body; in cephalopagus, it appears that two bodies share a head. How many human animals are present in these cases? One answer is that there are two in both cases—conjoined twins are precisely that, conjoined twins. Another is that the number of humans corresponds to the number of bodies—so there is one in dicephalus and two in cephalopagus. I show that both of these answers are incorrect. Prominent accounts of (...) biological individuation, which treat the organism as an integrated whole, reveal that in these and other cases of conjoined twinning the ‘twins’ share a single human animal. This has a number of consequences for the debate about what we are. First, if animalism is true, individuals of our kind can be—and are—profoundly psychologically divided. Second, cephalopagus twinning does not divide animalism from its rivals, as has been claimed. Finally, animalists can reply to a vicious species of the ‘too many thinkers’ problem to which they are allegedly uniquely vulnerable. (shrink)

A recent development in biology has been the growing acceptance that holobionts, entities comprised of symbiotic microbes and their host organisms, are widespread in nature. There is agreement that holobionts are evolved outcomes, but disagreement on how to characterize the operation of natural selection on them. The aim of this paper is to articulate the contours of the disagreement. I explain how two distinct foundational accounts of the process of natural selection give rise to competing views about evolutionary individuality.

Persons and Bodies develops and defends an account of persons and of the relation between human persons and their bodies. Human persons are constituted by bodies, without being identical to the bodies that constitute them—just as, I argue, statues are constituted by pieces of bronze, say, without being identical to the pieces of bronze that constitute them. The relation of constitution, therefore, is not peculiar to persons and their bodies, but is pervasive in the natural world.

Arguments that ordinary inanimate objects such as tables and chairs, sticks and stones, simply do not exist have become increasingly common and increasingly prominent. Some are based on demands for parsimony or for a non-arbitrary answer to the special composition question; others arise from prohibitions against causal redundancy, ontological vagueness, or co-location; and others still come from worries that a common sense ontology would be a rival to a scientific one. Until now, little has been done to address these arguments (...) in a unified and systematic way. Ordinary Objects is designed to fill this gap, demonstrating that the mistakes behind all of these superficially diverse eliminativist arguments may be traced to a common source. It aims to develop an ontology of ordinary objects subject to no such problems, providing perhaps the first sustained defense of a common sense ontology in two generations. The work done along the way addresses a number of major issues in philosophy of language and metaphysics, contributing to debates about analyticity, identity conditions, co-location and the grounding problem, vagueness, overdetermination, parsimony, and ontological commitment. In the end, the most important result of addressing these eliminativist arguments is not merely avoiding their conclusions; examining their failings also gives us reason to suspect that many apparent disputes in ontology are pseudo-debates. For it brings into question widely-held assumptions about which uses of metaphysical principles are appropriate, which metaphysical demands are answerable, and how we should go about addressing such fundamental questions as "What exists?". As a result, the work of Ordinary Objects promises to provide not only the route to a reflective understanding of our unreflective common-sense view, but also a better understanding of the proper methods and limits of metaphysics. (shrink)

One big question in biology is what life is, but another is how life divides into living things. This is the problem of biological individuality. Proposed statements of the problem have been vague and incomplete. And proposed theories of biological individuality are not detailed enough to solve the problem even if they are correct. The root of these troubles is that their authors have not recognized the metaphysical claims presupposed in their statement of the problem. Making these claims explicit will (...) enable us to see better what the problem is and what form a solution to it would need to have. (shrink)

What are the conditions under which one biological object is a part of another biological object? This paper answers this question by developing a general, systematic account of biological parthood. I specify two criteria for biological parthood. Substantial Spatial Inclusionrequires biological parts to be spatially located inside or in the region that the natural boundary of t he biological whole occupies. Compositional Relevance captures the fact that a biological part engages in a biological process that must make a necessary contribution (...) to a condition that is minimally sufficient to one or more of the characteristic behaviors of the biological whole. Instead of emphasizing the diversity of part-whole relations in the biological world, this paper asks what biological part-whole relations have in common and what constrains their existence, in general. After presenting the two criteria for biological parthood I discuss in how far my account can cope with hard cases (e.g., redundant parts) and I reveal the merits and limits of monism. (shrink)

I argue for the usefulness of the evolutionary kind of biological individual.

This book argues that a plausible account of emergence requires replacing the traditional assumption that what primarily exists are particular entities with generic processes. Traversing contemporary physics and issues of identity over time, it then proceeds to develop a metaphysical taxonomy of emergent entities and of the character of human life.

Immunology is central to contemporary biology and medicine, but it also provides novel philosophical insights. Its most significant contribution to philosophy concerns the understanding of biological individuality: what a biological individual is, what makes it unique, how its boundaries are established and what ensures its identity through time. Immunology also offers answers to some of the most interesting philosophical questions. What is the definition of life? How are bodily systems delineated? How do the mind and the body interact? In this (...) Element, Thomas Pradeu considers the ways in which immunology can shed light on these and other important philosophical issues. This title is also available as Open Access on Cambridge Core. (shrink)

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive literature began to (...) grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as “replicators” which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be “vehicles” of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units.The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to “organs” of group-level “organisms.” Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

In recent analytic metaphysics, the view that ‘ordinary inanimate objects such as sticks and stones, tables and chairs, simply do not exist’ has been defended by some noteworthy writers. Thomasson opposes such revisionary ontology in favour of an ontology that is conservative with respect to common sense. The book is written in a straightforward, methodical and down-to-earth style. It is also relatively non-specialized, enabling the author and her readers to approach problems that are often dealt with in isolation in a (...) more unified way.Thomasson's arguments are mainly counter-attacks on six ‘eliminativist’ arguments against ordinary objects. A causal redundancy argument espoused by Trenton Merricks holds that to suppose that there are ordinary objects is to suppose that these objects have distinctive causal powers. However, the casual efficacy of a baseball, for example, is exhausted by that of some suitably arranged …. (shrink)

This paper defends a substance-based metaphysics for organisms against three arguments for thinking that we should replace a substantial understanding of living things with a processual one, which are offered by Dan Nicholson and John Dupré in their edited collection, Everything Flows: Towards a Processual Philosophy of Biology. Dupré and Nicholson consider three main empirical motivations for the adoption of a process ontology in biology. These motivations are alleged to stem from facts concerning metabolism; the life cycles of organisms; and (...) ecological interdependence. The paper discusses each of the three arguments in turn and concludes that none gives us any compelling reason to abandon the metaphysics of things. At best, they are arguments against a kind of caricature substance metaphysics that ought never to have been in the running in any case. Then, at the end of the paper, it is suggested that there may be more positive arguments for insisting on retaining things in our metaphysics, arguments which, perhaps ironically get their main impetus from the phenomenon of life. (shrink)

What are the prospects for a monistic view of biological individuality given the multiple epistemic roles the concept must satisfy? In this paper, I examine the epistemic adequacy of two recent accounts based on the capacity to undergo natural selection. One is from Ellen Clarke, and the other is by Peter Godfrey-Smith. Clarke’s position reflects a strong monism, in that she aims to characterize individuality in purely functional terms and refrains from privileging any specific material properties as important in their (...) own right. I argue that Clarke’s functionalism impairs the epistemic adequacy of her account compared to a middle-ground position taken by Godfrey-Smith. In comparing Clarke and Godfrey-Smith’s account, two pathways emerge to pluralism about biological individuality. The first develops from the contrast between functionalist and materialist approaches, and the second from an underlying temporal structure involved in using evolutionary processes to define individuality. (shrink)

My topic is personal identity, or rather, our identity. There is general, but not, of course, unanimous, agreement that it is wrong to give an account of what is involved in, and essential to, our persistence over time which requires the existence of immaterial entities, but, it seems to me, there is no consensus about how, within, what might be called this naturalistic framework, we should best procede. This lack of consensus, no doubt, reflects the difficulty, which must strike anyone (...) who has considered the issue, of achieving, just in one's own thinking, a reflective equilibrium. The theory of personal identity, I feel, provides a curious contrast. On the one side, it seems highly important to know what sort of thing we are, but, on the other, it is hard to find any answer which has a ‘solid’ feel. (shrink)

The organism is one of the fundamental concepts of biology and has been at the center of many discussions about biological individuality, yet what exactly it is can be confusing. The definition that we find generally useful is that an organism is a unit in which all the subunits have evolved to be highly cooperative, with very little conflict. We focus on how often organisms evolve from two or more formerly independent organisms. Two canonical transitions of this type—replicators clustered in (...) cells and endosymbiotic organelles within host cells—demonstrate the reality of this kind of evolutionary transition and suggest conditions that can favor it. These conditions include co-transmission of the partners across generations and rules that strongly regulate and limit conflict, such as a fair meiosis. Recently, much attention has been given to associations of animals with microbes involved in their nutrition. These range from tight endosymbiotic associations like those between aphids and Buchnera bacteria, to the complex communities in animal intestines. Here, starting with a reflection about identity through time, we consider the distinctions between these kinds of animal–bacteria interactions and describe the criteria by which a few can be considered jointly organismal but most cannot. (shrink)

Biological individuality is a major topic of discussion in biology and philosophy of biology. Recently, several objections have been raised against traditional accounts of biological individuality, including the objections of monism, theory-centrism, ahistoricity, disciplinary isolationism, and the multiplication of conceptual uncertainties. In this introduction, I will examine the current philosophical landscape about biological individuality, and show how the contributions gathered in this special issue address these five objections. Overall, the aim of this issue is to offer a more diverse, unifying, (...) and scientifically informed conception of what a biological individual is. (shrink)

The Standard View of personal identity says that someone who exists now can exist at another time only if there is continuity of her mental contents or capacities. But no person is psychologically continuous with a fetus, for a fetus, at least early in its career, has no mental features at all. So the Standard View entails that no person was ever a fetus--contrary to the popular assumption that an unthinking fetus is a potential person. It is also mysterious what (...) does ordinarily happen to a human fetus, if it does not come to be a person. Although an extremely complex variant of the Standard View may allow one to persist without psychological continuity before one becomes a person but not afterwards, a far simpler solution is to accept a radically non-psychological account of our identity. (shrink)

This paper is about the neglected question of what sort of things we are metaphysically speaking. It is different from the mind-body problem and from familiar questions of personal identity. After explaining what the question means and how it differs from others, the paper tries to show how difficult it is to give a satisfying answer.

Most philosophers writing about personal identity in recent years claim that what it takes for us to persist through time is a matter of psychology. In this groundbreaking new book, Eric Olson argues that such approaches face daunting problems, and he defends in their place a radically non-psychological account of personal identity. He defines human beings as biological organisms, and claims that no psychological relation is either sufficient or necessary for an organism to persist. Olson rejects several famous thought-experiments dealing (...) with personal identity. He argues, instead, that one could survive the destruction of all of one's psychological contents and capabilities as long as the human organism remains alive--as long as its vital functions, such as breathing, circulation, and metabolism, continue. (shrink)

It is often said that the same particles can simultaneously make up two or more material objects that differ in kind and in their mental, biological and other qualitative properties. Others wonder how objects made of the same parts in the same arrangement and surroundings could differ in these ways. I clarify this worry and show that attempts to dismiss or solve it miss its point. At most one can argue that it is a problem we can live with.

In this paper, I argue that attempts in the philosophy of biology to show that organisms are processes rather than substances fail. Despite what process ontologists have said, I argue that substance ontology is perfectly able to accommodate the dynamic nature of organisms, their ecological dependence, and their vague boundaries, and that their criticisms are not directed at substance ontology simpliciter, but only at specific (perhaps untenable) characterisations of substances. The paper ends by considering what a processual philosophy of biology (...) that is radically in conflict with an ontology of substances might look like. (shrink)

Is the mammalian embryo/fetus a part of the organism that gestates it? According to the containment view, the fetus is not a part of, but merely contained within or surrounded by, the gestating organism. According to the parthood view, the fetus is a part of the gestating organism. This paper proceeds in two stages. First, I argue that the containment view is the received view; that it is generally assumed without good reason; and that it needs substantial support if it (...) is to be taken seriously. Second, I argue that the parthood view derives considerable support from a range of biological and physiological considerations. I tentatively conclude in favour of the parthood view, and end by identifying some of the interesting questions it raises. (shrink)

What is the metaphysical relationship between the fetus/embryo and the pregnant organism? In this paper I apply a substance metaphysics view developed by Barry Smith and Berit Brogaard to argue, on the basis of topological connectedness, that fetuses/embryos are Lady-Parts: part of the maternal organism up until birth. This leaves two options. Either mammalian organisms begin at birth, or we revise our conception of organisms such that mammalian organisms can be part of other mammals. The first option has some advantages: (...) it is numerically neat; aligns with an intuitive picture of organisms as physically distinct individuals; and ties ‘coming into existence’ to a suitably recognisable and important event: birth. But it denies that the fetus survives birth, or that human organisms existed prior to their birth. The second option allows us to recognise that human organisms exist prior to and survive their birth, but at a cost: it leaves the question of when an organism comes into existence unanswered, and demands potentially far-reaching conceptual revision across a range of domains. (shrink)

Mammals are usually considered unproblematic as biological individuals. This article contends the opposite. Once we consider pregnancy, criteria for biological individuality are not easily applicab...

We address three fundamental questions: What does it mean for an entity to be living? What is the role of inter-organismic collaboration in evolution? What is a biological individual? Our central argument is that life arises when lineage-forming entities collaborate in metabolism. By conceiving of metabolism as a collaborative process performed by functional wholes, which are associations of a variety of lineage-forming entities, we avoid the standard tension between reproduction and metabolism in discussions of life – a tension particularly evident (...) in discussions of whether viruses are alive. Our perspective assumes no sharp distinction between life and non-life, and does not equate life exclusively with cellular or organismal status. We reach this conclusion through an analysis of the capabilities of a spectrum of biological entities, in which we include the pivotal case of viruses as well as prions, plasmids, organelles, intracellular and extracellular symbionts, unicellular and multicellular life-forms. The usual criterion for classifying many of the entities of our continuum as non-living is autonomy. This emphasis on autonomy is problematic, however, because even paradigmatic biological individuals, such as large animals, are dependent on symbiotic associations with many other organisms. These composite individuals constitute the metabolic wholes on which selection acts. Finally, our account treats cooperation and competition not as polar opposites but as points on a continuum of collaboration. We suggest that competitive relations are a transitional state, with multi-lineage metabolic wholes eventually outcompeting selfish competitors, and that this process sometimes leads to the emergence of new types or levels of wholes. Our view of life as a continuum of variably structured collaborative systems leaves open the possibility that a variety of forms of organized matter – from chemical systems to ecosystems – might be usefully understood as living entities. (shrink)

We provide an analysis of the public's having warranted epistemic trust in science, that is, the conditions under which the public may be said to have well-placed trust in the scientists as providers of information. We distinguish between basic and enhanced epistemic trust in science and provide necessary conditions for both. We then present the controversy regarding the connection between autism and measles–mumps–rubella vaccination as a case study to illustrate our analysis. The realization of warranted epistemic public trust in science (...) requires various societal conditions, which we briefly introduce in the concluding section. (shrink)

Biological species have been treated traditionally as spatiotemporally unrestricted classes. If they are to perform the function which they do in the evolutionary process, they must be spatiotemporally localized individuals, historical entities. Reinterpreting biological species as historical entities solves several important anomalies in biology, in philosophy of biology, and within philosophy itself. It also has important implications for any attempt to present an "evolutionary" analysis of science and for sciences such as anthropology which are devoted to the study of single (...) species. (shrink)

Mammalian placental pregnancy is a neglected problem case for theories of organismality. This example is closer to home than those typically discussed within philosophy of biology. I apply evolutio...

Individuality is an important concept in biology, yet there are many non-equivalent criteria of individuality expressed in different kinds of biological individuals. This article evaluates these different kinds in terms of their capacity to support explanatory generalizations over the systems they individuate. Viewing the problem of individuality from this perspective promotes a splitting strategy in which different kinds make different epistemic trade-offs that suit them for different explanatory roles. I argue that evolutionary individuals, interpreted as forming a functional kind, face (...) difficulties of individuation and explanatory power that are mitigated by relying on more structurally based properties and non-evolutionary kinds. 1Introduction2Kinds of Biological Individuals3Evolutionary Individuals and Functional Kinds4Evolutionary versus Non-evolutionary Kinds of Individuals 4.1Physiological individuality4.2Ecological individuality4.3Developmental individuality5Conclusion. (shrink)

This is one of the first books in a new series that will publish the very best work in the philosophy of biology. The series will be non-sectarian in character, will extend across the broadest range of topics, and will be genuinely interdisciplinary. The Immune Self is a critical study of immunology from its origins at the end of the nineteenth century to its contemporary formulation. The book offers the first extended philosophical critique of immunology, in which the function of (...) the term 'self' that underlies the structure of current immune theory is analysed. However, this analysis is carefully integrated into a broad survey of the major scientific developments in immunology, a discussion of their historical context, and a review of the conceptual arguments that have moulded this sophisticated modern science. (shrink)

What kind of thing are we? Paul Snowdon's answer is that we are animals, of a sort. This view--'animalism'--may seem obvious but on the whole philosophers have rejected it. Snowdon argues that animalism is a defensible way of thinking about ourselves. Its rejection rests on the tendency when doing philosophy to mistake fantasy for reality.

The Limits of the Self, will be essential reading for anyone interested in the definition of biological individuality and the understanding of the immune system.

What makes a biological entity an individual? Jack Wilson shows that past philosophers have failed to explicate the conditions an entity must satisfy to be a living individual. He explores the reason for this failure and explains why we should limit ourselves to examples involving real organisms rather than thought experiments. This book explores and resolves paradoxes that arise when one applies past notions of individuality to biological examples beyond the conventional range and presents an analysis of identity and persistence. (...) The book's main purpose is to bring together two lines of research, theoretical biology and metaphysics, which have dealt with the same subject in isolation from one another. Wilson explains an alternative theory about biological individuality which solves problems which cannot be addressed by either field alone. He presents a more fine-grained vocabulary of individuation based on diverse kinds of living things, allowing him to clarify previously muddled disputes about individuality in biology. (shrink)

Substance has been a leading idea in the history of Western philosophy. _Joshua Hoffman and Gary S. Rosenkrantz_ explain the nature and existence of individual substances, including both living things and inanimate objects. Specifically written for students new to this important and often complex subject, _Substance_ provides both the historical and contemporary overview of the debate. Great Philosophers of the past, such as Aristotle, Descartes, Spinoza, Leibnitz, Locke, and Berkeley were profoundly interested in the concept of substance. And, the authors (...) argue, a belief in the existence of substances is an integral part of our everyday world view. But what constitutes substance? Was Aristotle right to suggest that artefacts like tables and ships don't really exist? _Substance: Its Nature and Existence_ is one of the first non-technical, accessible guides to this central problem and will be of great use to students of metaphysics and philosophy. (shrink)

What is a human person, and what is the relation between a person and his or her body? In her third book on the philosophy of mind, Lynne Rudder Baker investigates what she terms the person/body problem and offers a detailed account of the relation between human persons and their bodies. Baker's argument is based on the 'Constitution View' of persons and bodies, which aims to show what distinguishes persons from all other beings and to show how we can be (...) fully material beings without being identical to our bodies. The Constitution View yields answers to the questions 'What am I most fundamentally?', 'What is a person?', and 'What is the relation between human persons and their bodies'? Baker argues that the complex mental property of first-person perspective enables one to conceive of one's body and mental states as one's own. (shrink)

Among the questions to be raised under the heading of “personal identity” are these: “What are we?” (fundamental nature question) and “Under what conditions do we persist through time?” (persistence question). Against the dominant neo-Lockean approach to these questions, the view known as animalism answers that each of us is an organism of the species Homo sapiens and that the conditions of our persistence are those of animals. Beyond describing the content and historical background of animalism and its rivals, this (...) entry explores some of the arguments for and objections to this controversial account of our nature and persistence. (shrink)

The question “What is an organism?”, formerly considered as essential in biology, has now been increasingly replaced by a larger question, “What is a biological individual?”. On the grounds that i) individuation is theory-dependent, and ii) physiology does not offer a theory, biologists and philosophers of biology have claimed that it is the theory of evolution by natural selection which tells us what counts as a biological individual. Here I show that one physiological field, immunology, offers a theory, which makes (...) possible a biological individuation based on physiological grounds. I give a new answer to the question of the individuation of an organism by linking together the evolutionary and the immunological approaches to biological individuation. (shrink)