Elements in the Philosophy of Biology – serie

Physarum polycephalum, also known more colloquially as 'the blob', 'acellular slime mould', or just 'slime mould', is a unicellular multinucleate protist that has continued to attract the interest of biologists over the past century because of its complex life cycle, unique physiology, morphology, and behaviour. More recently, attention has shifted to Physarum as a model organism for investigating putative cognitive capacities such as decision making, learning, and memory in organisms without nervous systems. The aim of this Element is to illustrate how Physarum can be used as a valuable tool for approaching various topics in the philosophy of biology. Physarum and its behaviour not only pose a challenge to some of the received views of biological processes but also, I shall argue, provide an opportunity to clarify and appropriately sharpen the concepts underlying such received views.

In this Element, we extend our earlier treatment of biology's first law. The law says that in any evolutionary system in which there is variation and heredity, there is a tendency for diversity and complexity to increase. The law plays the same role in biology that Newton's first law plays in physics, explaining what biological systems are expected to do when no forces act, in other words, what happens when nothing happens. Here we offer a deeper explanation of certain features of the law, develop a quantitative version of it, and explore its consequences for our understanding of diversity and complexity.

This Element is an introduction to the metaphysics of biology, a very general account of the nature of the living world. The first part of the Element addresses more traditionally philosophical questions - whether biological systems are reducible to the properties of their physical parts, causation and laws of nature, substantialist and processualist accounts of life, and the nature of biological kinds. The second half will offer an understanding of important biological entities, drawing on the earlier discussions. This division should not be taken too seriously, however: the topics in both parts are deeply interconnected. Although this does not claim to be a scientific work, it does aim to be firmly grounded in our best scientific knowledge; it is an exercise in naturalistic metaphysics. Its most distinctive feature is that argues throughout for a view of living systems as processes rather than things or, in the technical philosophical sense, substances.

The biological world is full of phenomena that seem to run counter to Darwin's insight that natural selection can lead to the appearance of design. For instance, why do organisms in some species divide reproductive labor? The existence of non-reproducing organisms in such 'eusocial' species looks to be at odds with an evolutionary theory which posits traits exist because they help organisms survive and reproduce. What is the evolutionary advantage of an insect being distasteful to its predators? The distastefulness appears designed to deter predators, but can only affect the predator's actions when the insect is eaten; it is hard to see how such a trait could be passed on. This Element will cover the shared foundations of evolutionary explanations for these and other seemingly puzzling phenomena, focusing on the concepts of inclusive fitness and kin selection.

The crucial role of animal models in biomedical research calls for philosophical investigation of how and whether knowledge about human diseases can be gained by studying other species. This Element delves into the selection and construction of animal models to serve as preclinical substitutes for human patients. It explores the multifaceted roles animal models fulfil in translational research and how the boundaries between humans and animals are negotiated in this process. The book also covers persistent translational challenges that have sparked debates across scientific, philosophical, and public arenas regarding the limitations and future of animal models. Among the are persistent tensions between standardization and variation in medicine, as well as between strategies aiming to reduce and recapitulate biological complexity. Finally, the book examines the prospects of replacing animal models with animal-free methods. The Element demonstrates why animal modeling should be of interest to philosophers, social scientists, and scientists alike.

This Element introduces Aristotle's doctrine of hylomorphism, which provides an account of substances in terms of their 'matter' and 'form', adapting and applying it to the interface between physics and biology. It begins by indicating some reasons for the current revival of hylomorphism and by suggesting a way of classifying the confusing array of hylomorphisms that have arisen. It argues that, in order for composite entities to have irreducible causal powers which make a difference to how nature unfolds, they must have substantial forms which transform their matter such that the powers of their physical parts are grounded in the composite entity as a whole. It suggests how a contemporary form of hylomorphism might contribute to the philosophy of biology by grounding the non-intentional form of teleology that features in the identity conditions of biological systems, affirming a real distinction between living organisms and heaps of matter. This title is also available as Open Access on Cambridge Core.

The history of biology is mottled with disputes between two distinct approaches to the organic world: structuralism and functionalism. Their persistence across radical theory change makes them difficult to characterize: the characterization must be abstract enough to capture biologists with diverse theoretical commitments, yet not so abstract as to be vacuous. This Element develops a novel account of structuralism and functionalism in terms of explanatory strategies (Section 2). This reveals the possibility of integrating the two strategies; the explanatory successes of evolutionary-developmental biology essentially depend on such integration (Section 3). Neither explanatory strategy is universally subordinate to the other, though subordination with respect to particular explanatory tasks is possible (Section 4). Beyond structuralism and functionalism, philosophical analysis that centers explanatory strategies can illuminate conflicts within evolutionary theory more generally (Section 5).

Debates concerning the units and levels of selection have persisted for over fifty years. One major question in this literature is whether units and levels of selection are genuine, in the sense that they are objective features of the world, or merely reflect the interests and goals of an observer. Scientists and philosophers have proposed a range of answers to this question. This Element introduces this literature and proposes a novel contribution. It defends a realist stance and offers a way of delineating genuine levels of selection by invoking the notion of a functional unit.

Recent arguments concerning the nature of causation in evolutionary theory, now often known as the debate between the 'causalist' and 'statisticalist' positions, have involved answers to a variety of independent questions - definitions of key evolutionary concepts like natural selection, fitness, and genetic drift; causation in multi-level systems; or the nature of evolutionary explanations, among others. This Element offers a way to disentangle one set of these questions surrounding the causal structure of natural selection. Doing so allows us to clearly reconstruct the approach that some of these major competing interpretations of evolutionary theory have to this causal structure, highlighting particular features of philosophical interest within each. Further, those features concern problems not exclusive to the philosophy of biology. Connections between them and, in two case studies, contemporary metaphysics and philosophy of physics demonstrate the potential value of broader collaboration in the understanding of evolution.

Erwin Schrödinger's What Is Life? is one of the most celebrated scientific works of the twentieth century. However, like most classics, it is far more often cited than read. Efforts to seriously engage with Schrödinger's arguments are rare. This Element explores how well his ideas have stood the test of time. It argues that Schrödinger's emphasis on the rigidity and specificity of the hereditary material (which stemmed from his attempt to explain biological order from physical principles) influenced how molecular biologists conceptualized macromolecules, resulting in a deterministic, engineering view of the cell that is still popular today-even if it is increasingly at odds with experimental findings. Drawing on archival sources, this Element also uncovers Schrödinger's motivations in writing What Is Life? and suggests that his biological proposals are best understood in the context of his longstanding dispute with other physicists regarding the interpretation and extension of quantum mechanics.

Evolutionary theory has found its way into a staggeringly large diversity of fields outside the biological sciences. This Element examines how crossovers of evolutionary theory from biology into other fields occur, and in what ways such fields can be meaningfully considered evolutionary fields of research. Cases of crossover of evolutionary theory have so far not been examined systematically by philosophers of science, and this Element aims to start with developing a philosophical account of this practice as a general strategy in science. It shows that theory crossovers do not consist in straightforward applications of a generally accepted version of evolutionary theory to non-biological phenomena, but must be understood differently. Alternatively, it is suggested that crossovers of evolutionary theory involve a general style of thinking and shown how this provides a unifying perspective on crossovers of evolutionary theory between fields. This title is also available as Open Access on Cambridge Core.

The history of developmental biology is interwoven with debates as to whether mechanistic explanations of development are possible or whether alternative explanatory principles or even vital forces need to be assumed. In particular, the demonstrated ability of embryonic cells to tune their developmental fate precisely to their relative position and the overall size of the embryo was once thought to be inexplicable in mechanistic terms. Taking a causal perspective, this Element examines to what extent and how developmental biology, having turned molecular about four decades ago, has been able to meet the vitalist challenge. It focuses not only on the nature of explanations but also on the usefulness of causal knowledge - including the knowledge of classical experimental embryology - for further scientific discovery. It also shows how this causal perspective allows us to understand the nature and significance of some key concepts, including organizer, signal and morphogen. This title is also available as Open Access on Cambridge Core.

Recent interest in the evolution of the social contract is extended by providing a throughly naturalistic, evolutionary account of the biological underpinnings of a social contract theory of morality. This social contract theory of morality (contractevolism) provides an evolutionary justification of the primacy of a moral principle of maximisation of the opportunities for evolutionary reproductive success (ERS), where maximising opportunities does not entail an obligation on individuals to choose to maximise their ERS. From that primary principle, the moral principles of inclusion, individual sovereignty (liberty) and equality can be derived. The implications of these principles, within contractevolism, are explored through an examination of patriarchy, individual sovereignty and copulatory choices, and overpopulation and extinction. Contractevolism is grounded in evolutionary dynamics that resulted in humans and human societies. The most important behavioural consequences of evolution to contractevolism are reciprocity, cooperation, empathy, and the most important cognitive consequences are reason and behavioural modification.

This Element introduces the Disambiguating Project (DP) about the units of selection. By DP, the authors mean the thesis that the expression 'units of selection' refers to at least three non-co-extensional functional concepts: interactor, replicator/reproducer/reconstitutor, and manifestor of adaptation/type-1 agent. They present each concept and demonstrate the necessity of their isolation, because each of them responds to a distinct question about the units of selection, and these distinct questions are not always posed in combination in today's biological research. They further apply the framework to the analysis of the debates concerning the Evolutionary Transitions in Individuality (ETI) and argue that the DP interprets the ETI better than any project rejecting the three meanings of 'units of selection.' Thus, they claim that the differentiation between at least these three functional concepts is fundamental to clarify some conceptual confusions in biology, which rest on the conflation of these distinct meanings.

This Element examines philosophical accounts of scientific explanation, particularly those that apply to biology and the life sciences. Two main categories of scientific explanation are examined in detail -causal explanations and non-causal explanations. The first section of this Element provides a brief history and some basics on philosophical accounts of scientific explanation. Section 2 covers causal explanation, first by discussing foundational topics in the area, such as defining causation, causal selection, and reductive explanation. This is followed by an examination of distinct types of causal explanation, including those that appeal to mechanisms pathways, and cascades. The third section covers non-causal, mathematical explanations, which have received significant attention in philosophy of biology and the life sciences. Three main types of non-causal, mathematical explanation are discussed: topological and constraint-based explanation, optimality and efficiency explanations, and minimal model explanations. This title is also available as Open Access on Cambridge Core.

Control is a key ingredient of scientific experimentation; arguably, an uncontrolled intervention or manipulation is not even a genuine experiment. Experiments in the life sciences, however, are notoriously difficult to control due to the complexity and variability of living things. This Element discusses general features of controlled experimentation, epistemic and practical aspects, and historical perspectives. It argues that controlled experimentation has a material-technical and a conceptual side. It shifts the focus from control experiments, comparisons with a control, to the broader issue of controlling for background factors as the epistemologically fundamental issue in experimentation. To understand the nature of controlled experimentation, one needs to consider the making - the design phase - of controlled experiments, particularly the conceptualization and treatment of background factors. The making of controlled experiments is at the same time constitutive for the knowledge that can be gained in the experiment, contingent on a research situation, and historically shaped.

Time is ripe to complement the question 'what is health and disease?' in philosophy of medicine with a 'philosophy of physiology.' Indeed, the actors in this debate share the conviction that a 'foundational' concept dictates to this scientific field what is to be considered healthy or pathological and leaves it to explore only facts and mechanisms. Rejecting this presupposition, philosophy of physiology accepts that biomedical sciences explore and redefine their own object: the healthy, the pathological. Indeed, various theories of disease and health, that philosophers have rarely studied, form the core of biomedical research, too hastily considered as a science 'without theories.' The Element identifies them, and clarifies their content, presuppositions, and scope. Finally, it proposes a new question about the unity of the pathological phenomenon: not 'what do all diseases have in common?' but rather, 'why is the susceptibility to disease a universal and necessary characteristic of living beings?'

The history of biology is mottled with disputes between two distinct approaches to the organic world: structuralism and functionalism. Their persistence across radical theory change makes them difficult to characterize: the characterization must be abstract enough to capture biologists with diverse theoretical commitments, yet not so abstract as to be vacuous. This Element develops a novel account of structuralism and functionalism in terms of explanatory strategies (Section 2). This reveals the possibility of integrating the two strategies; the explanatory successes of evolutionary-developmental biology essentially depend on such integration (Section 3). Neither explanatory strategy is universally subordinate to the other, though subordination with respect to particular explanatory tasks is possible (Section 4). Beyond structuralism and functionalism, philosophical analysis that centers explanatory strategies can illuminate conflicts within evolutionary theory more generally (Section 5).

This Element develops a view about biological individuality's value in two ways: while biological individuality matters for its theoretical and methodological roles in the production of scientific knowledge, its historical use in promoting the politics of social ideologies concerning progress and perfection of humanity's evolutionary future must not be ignored. Recent trends in biological individuality are analyzed and set against the history of evolutionary thought drawing from the early twentieth century. This title is also available as Open Access on Cambridge Core.

Living systems are complex systems made of components that tend to degrade, but nonetheless they maintain themselves far from equilibrium. This requires living systems to extract energy and materials from the environment and use them to build and repair their parts by regulating their activities based on their internal and external conditions in ways that allow them to keep living. The philosophical and theoretical approach discussed in this Element aims to explain these features of biological systems by appealing to their organization. It addresses classical and more recent issues in philosophy of biology, fromorigins and definitions of life to biological teleology and functions, from an original perspective mainly focused on the living system, its physiology and behavior, rather than evolution. It discusses and revises the conceptual foundations of this approach and presents an updated version of it. This title is also available as Open Access on Cambridge Core.

This Element introduces Aristotle's doctrine of hylomorphism, which provides an account of substances in terms of their 'matter' and 'form', adapting and applying it to the interface between physics and biology. It begins by indicating some reasons for the current revival of hylomorphism and by suggesting a way of classifying the confusing array of hylomorphisms that have arisen. It argues that, in order for composite entities to have irreducible causal powers which make a difference to how nature unfolds, they must have substantial forms which transform their matter such that the powers of their physical parts are grounded in the composite entity as a whole. It suggests how a contemporary form of hylomorphism might contribute to the philosophy of biology by grounding the non-intentional form of teleology that features in the identity conditions of biological systems, affirming a real distinction between living organisms and heaps of matter. This title is also available as Open Access on Cambridge Core.

Human nature is frequently evoked to characterize our species and describe how it differs from others. But how should we understand this concept? What is the nature of a species? Some take our nature to be an essence and argue that because humans lack an essence, they also lack a nature. Others argue for non-essentialist ways of understanding human nature, which usually aim to provide criteria for sorting human traits into one of two bins, the one belonging to our nature and the other outside our nature. This Element argues that both the essentialist and trait bin approaches are misguided. Instead, the author develops a trait cluster account of human nature, which holds that human nature is based on the distribution of our traits over our (actual and possible) life histories. One benefit of this account is that it aligns human nature with the human sciences, rendering the central concern of the human sciences to be the study of human nature. This title is also available as Open Access on Cambridge Core.

This Element introduces the Disambiguating Project (DP) about the units of selection. By DP, the authors mean the thesis that the expression 'units of selection' refers to at least three non-co-extensional functional concepts: interactor, replicator/reproducer/reconstitutor, and manifestor of adaptation/type-1 agent. They present each concept and demonstrate the necessity of their isolation, because each of them responds to a distinct question about the units of selection, and these distinct questions are not always posed in combination in today's biological research. They further apply the framework to the analysis of the debates concerning the Evolutionary Transitions in Individuality (ETI) and argue that the DP interprets the ETI better than any project rejecting the three meanings of 'units of selection.' Thus, they claim that the differentiation between at least these three functional concepts is fundamental to clarify some conceptual confusions in biology, which rest on the conflation of these distinct meanings.

This Element discusses the central role of models within evolutionary biology, offering an accessible introduction and synthesis of literature in both evolutionary biology and the philosophy of models. We will examine three questions: first, what does it mean to be a 'model' and to engage in 'modelling'? Second, what types of models are employed within evolutionary biology? Third, how can models of evolution be tested? In exploring the answers to these questions, this Element hopes to highlight how evolutionary biology and philosophy of biology can usefully interact to understand conceptual and methodological problems arising from modelling evolution.

This Element discusses the central role of models within evolutionary biology, offering an accessible introduction and synthesis of literature in both evolutionary biology and the philosophy of models. We will examine three questions: first, what does it mean to be a 'model' and to engage in 'modelling'? Second, what types of models are employed within evolutionary biology? Third, how can models of evolution be tested? In exploring the answers to these questions, this Element hopes to highlight how evolutionary biology and philosophy of biology can usefully interact to understand conceptual and methodological problems arising from modelling evolution.

The biological world is full of phenomena that seem to run counter to Darwin's insight that natural selection can lead to the appearance of design. For instance, why do organisms in some species divide reproductive labor? The existence of non-reproducing organisms in such 'eusocial' species looks to be at odds with an evolutionary theory which posits traits exist because they help organisms survive and reproduce. What is the evolutionary advantage of an insect being distasteful to its predators? The distastefulness appears designed to deter predators, but can only affect the predator's actions when the insect is eaten; it is hard to see how such a trait could be passed on. This Element will cover the shared foundations of evolutionary explanations for these and other seemingly puzzling phenomena, focusing on the concepts of inclusive fitness and kin selection.

The intersection of development and evolution has always harbored conceptual issues, but many of these are on display in contemporary evolutionary developmental biology (evo-devo). These issues include: (1) the precise constitution of evo-devo, with its focus on both the evolution of development and the developmental basis of evolution, and how it fits within evolutionary theory; (2) the nature of evo-devo model systems that comprise the material of comparative and experimental research; (3) the puzzle of how to understand the widely used notion of 'conserved mechanisms'; (4) the definition of evolutionary novelties and expectations for how to explain them; and (5) the demand of interdisciplinary collaboration that derives from investigating complex phenomena at key moments in the history of life, such as the fin-limb transition. This Element treats these conceptual issues with close attention to both empirical detail and scientific practice to offer new perspectives on evolution and development. This title is also available as Open Access on Cambridge Core.

Time is ripe to complement the question 'what is health and disease?' in philosophy of medicine with a 'philosophy of physiology.' Indeed, the actors in this debate share the conviction that a 'foundational' concept dictates to this scientific field what is to be considered healthy or pathological and leaves it to explore only facts and mechanisms. Rejecting this presupposition, philosophy of physiology accepts that biomedical sciences explore and redefine their own object: the healthy, the pathological. Indeed, various theories of disease and health, that philosophers have rarely studied, form the core of biomedical research, too hastily considered as a science 'without theories.' The Element identifies them, and clarifies their content, presuppositions, and scope. Finally, it proposes a new question about the unity of the pathological phenomenon: not 'what do all diseases have in common?' but rather, 'why is the susceptibility to disease a universal and necessary characteristic of living beings?'

Physarum polycephalum, also known more colloquially as 'the blob', 'acellular slime mould', or just 'slime mould', is a unicellular multinucleate protist that has continued to attract the interest of biologists over the past century because of its complex life cycle, unique physiology, morphology, and behaviour. More recently, attention has shifted to Physarum as a model organism for investigating putative cognitive capacities such as decision making, learning, and memory in organisms without nervous systems. The aim of this Element is to illustrate how Physarum can be used as a valuable tool for approaching various topics in the philosophy of biology. Physarum and its behaviour not only pose a challenge to some of the received views of biological processes but also, I shall argue, provide an opportunity to clarify and appropriately sharpen the concepts underlying such received views.