Essence in the Age of Evolution

A New Theory of Natural Kinds

Christopher J. Austin

• Publisher: Routledge
• Year: 2018
• ISBN:
  9781351240833
• Edition: 1
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

This book offers a novel defence of a highly contested philosophical position: biological natural kind essentialism. This theory is routinely and explicitly rejected for its purported inability to be explicated in the context of contemporary biological science, and its supposed incompatibility with the process and progress of evolution by natural selection. Christopher J. Austin challenges these objections, and in conjunction with contemporary scientific advancements within the field of evolutionary-developmental biology, the book utilises a contemporary neo-Aristotelian metaphysics of "dispositional properties", or causal powers, to provide a theory of essentialism centred on the developmental architecture of organisms and its role in the evolutionary process. By defending a novel theory of Aristotelian biological natural kind essentialism, Essence in the Age of Evolution represents the fresh and exciting union of cutting-edge philosophical insight and scientific knowledge.

1 Biological Natural Kind Essentialism

Definitions and Desiderata

First things first—what exactly is a natural kind, and what does the claim that a natural kind has an essence amount to? As with most philosophical terms of art, ‘natural kind’ and ‘essentialism’ are often used by so many different philosophers and for a variety of distinct reasons that one must quite specifically delineate their desired meaning before undertaking a project which utilises them. The first chapter of this book does just that, focusing on what I take to be the central concepts that are associated with each term. Once I have laid out the intent and scope of ‘natural kind’, I move on to defining the basics of the theory at the centre of this book—natural kind essentialism. Importantly, however, it is a specific form of that theory—Aristotelian natural kind essentialism—which is the fundamental focus of this work, as it is its central tenets which motivate and animate the theory which this work culminates in. In this first chapter, then, after discussing the more general concept of ‘natural kind essentialism’, I detail the particulars of Aristotle’s unique brand and what I take to be its primary theoretical virtues, and offer a brief sketch of what the foundation of a contemporary, neo-Aristotelian natural kind essentialism about biological natural kinds might look like.

1.1 The Philosophical Theory of Natural Kinds

The natural world that surrounds us and of which we are a part ostensibly appears to be structured in certain ways. There seem to be, for instance, rather particular ways in which the physical world is divided up into discrete entities, and among the collection of these entities which make up that world, these ways are evidentially reiterated many times over. Nature, it would seem, abhors an undifferentiated, blurry mass of existential white noise: the entities of the natural world have structure, and the whole of that world is filled up with various repetitions of those structures. Not only do we find that there are particular structures repeated throughout the natural divisions of the biological world but also that these structures appear to form distinct collections—among them are, for instance, the plants, the insects, the arthropods, and the tetrapods—which we come to know by our recognition of the inherent structural similarities among their members. Furthermore, the structural similarities between the members of these collections—be they anatomical, eidonomical, or physiological—appear to be no mere artifice of human convention: that the denizens of the biological world belong to these collections is a fact about the world, not about us. Such is the basic story of realism about natural kinds.¹

Of course, though the simplistic story outlined earlier does capture the main intuitions at play, we need to put more flesh upon that rather bare-boned outline in order to arrive at a more robust, philosophical concept of natural kinds. To begin with, let us define a kind as an ontological category defined by a set of properties p where any entity x belongs to a kind k if and only if x possesses p. While this simple definition is suitable, it is also incomplete. For not just any set of properties are capable of delineating a proper natural kind—there are two important criteria associated with that philosophical concept that those sets must meet: one ontological, the other epistemological. On the ontological front, that set’s constituents and their composition must be suitably ‘natural’. There is now a large and complex literature on the subject of metaphysical naturalness, but with respect to kinds, the ‘naturalness’ at issue is largely tantamount to mind-independence.² A kind is a natural kind then in virtue of the existence of its properties and the coalescence of their collection both being a consequence of nature, rather than of nous—that is, rather than being a result of our theoretical interests, scientific conventions, or common conceptual practices. On the epistemological front, the set of properties which define a natural kind must be inductively rich in such a way that, in virtue of their possessing that set, we are sufficiently licenced in our ability to make a wide variety of inductive generalisations about the typical further and future property possession—as well as the limits thereon—of its members. A natural kind, in other words, must be demarcated by a set of properties which reliably licence an extensive range of possibility and probability judgements about the entities which possess it.³ The satisfaction of these two criteria in a proper concept of natural kinds, as discussed in more detail next, results in a theory according to which there exist ontologically privileged divisions among nature’s denizens founded in their possession of particular sets of properties which function as the epistemological ground for the predictive prowess of our scientific knowledge about them.

Importantly, being a realist about natural kinds doesn’t commit one to denying either the existence of mind-dependent, or socially constructed kinds, or that our recognition and employment of such kinds has the ability to grant us inductive insights about the workings of the world. Even if ‘stamp collector’, for instance, is a thoroughly mind-dependent classificatory division, there are undoubtedly members of that kind, and their membership certainly licences our ability to make a variety of inductive inferences about them: that they have an affinity for organisation and cataloguing, that they likely own a magnifying glass, that they are likely to purchase limited-edition printings published by Royal Mail, etc. Furthermore, the realist about natural kinds need not deny that the collections carved out by mind-dependent kinds, however profligate in number and permissive in membership criteria, are partly grounded in objective, mind-independent features of the world: irrespective of our classificatory practices, every stamp collector has many features in common with every other.⁴ For the realist about natural kinds, however, the kinds established by human convention, however anchored they may be in the objective features of their members, are mere mirages of the natural and naturally privileged divisions which constitute the fundamental architectural facets of the world, and which ontologically undergird our most successful and insightful inferences about its operation.

But what precisely does this central mind-independence claim of the natural kind realist amount to? I’ve already given a rather intuitive sense of what it means for a property grouping that defines a particular kind to be suitably mind-independent, one which corresponds to the well-worn Platonic adage that such collections “carve nature at the joints”: they represent sharp divisions in the world which act as ontological boundaries around particular repeatable types of entities.⁵ Inherent in this colourful phrasing is the important idea that when we approach the world, our conceptual dissection of its constituents is objectively constrained in such a way that any classificatory cutting we wish to make must take place around its ossified contours. Another, perhaps more instructive way we might cash out the mind-independence claim of natural kind realism is via negativa—as the denial of the claim that the property groupings which define a natural kind are those formed, held together, and susceptible to revision by our semantic practices for the purposes of their utility in our identification and taxonomic enterprises. It might be the case, in some suitably perfected science, that some of these types of properties do in fact belong to the collection which truly defines a particular natural kind—but the important point here is that it is neither a necessary nor sufficient condition on properties belonging to that collection that they are of that type.

The now classic distinction in operation here is Locke’s division between ‘real’ and ‘nominal’ sets of defining properties in his An Essay Concerning Human Understanding (1689). In Book III of the Essay, Locke makes the distinction between the property groupings that we collect together to use in our definition of entities for the purposes of identification, classification, etc., and the mind-cum-interest independent ones which nature herself has collated—the former he dubbed ‘nominal’, the latter ‘real’. The nominal definition of a kind corresponds to the grouping of properties which we typically associate with and subsequently deploy as a reliably guided criterion for picking out and cataloguing entities as belonging to that kind in virtue of their possessing this collection.⁶ We quite commonly identify members of the ‘tiger’ kind, for instance, by noting their being ‘striped’, ‘predatory’, ‘four-legged’, ‘ferocious’, and ‘feral’ entities—and while this collection isn’t wholly arbitrary, it is certainly one that human interest and societal convention has, at least partly, conceptually cobbled together.

Real definitions of kinds, on the other hand, correspond to the property groupings that, although they may be “constantly found to coexist with the nominal [groupings]” are nonetheless such that they are formed “without any relation to anything without [themselves]”—that is, they are a collection of properties which have a “union in nature whether the mind joins them or not”.⁷ In other words, the real definition of a natural kind corresponds to a group of properties that represent a division which nature makes, not us: they are neither created by human convention nor subject to the whims of conceptual revision. To return to our example, quite independently of our recognition or acknowledgement, the naturally compresent property collection which defines the kind ‘tiger’ might plausibly include a rather specific genetic constitution, a particular lineage relation, the participation in a circumscribed breeding pool, etc. The collection of properties which define natural kinds—those that are included in their real definitions—are not then simply lists of properties that help us, to borrow a bit of phrasing from the contemporary literature, “fix the reference” of those kind terms: such lists do not necessarily (and very often, definitively do not) correspond to the property collections which represent the objective, “joint-carving” divisions inherent in the natural world. The natural kind realist’s commitment to mind-independence then amounts to upholding the claim that the world consists of more than merely nominally defined kinds and thus, as Elder (2008: 341) succinctly puts it, that

quite apart from what [kind terms] we may fashion, and what condition we may lay down on the satisfaction of those [terms], certain properties just do cluster together, in instance after instance, as a function of the way the world works.

In addition to providing a conceptual framework for understanding the ontological commitments of natural kind realism, utilising this Lockean distinction also aids in the explication of the aforementioned epistemological component of that theory. To see how, it is important to note that, even if their composition is in some respects subject to mind-dependent arbitration, the property collections which constitute the nominal definitions of natural kinds are not wholly arbitrary. Indeed, some such collections are better than others, and the best of them—that is, the ones which most successfully support our identification and classification of natural entities—are the ones which easily and reliably track the members of the world’s natural kinds. The success of those collections in this respect depends on a simple fact: they represent the surface level and typical features of the members of those kinds. From the standpoint of mere phenomenological accessibility, detecting the ‘striped’ features of ‘four-legged’ entities really does aid in our identification of them as members of the ‘tiger’ kind, and it does so in no small part because these are properties which rather dependably continually crop up across a wide range of members of that kind.⁸ That there is, in the case of our best nominal definitions of natural kinds, a type of dependence between those collections and those that make up their real definitions, illustrates the way in which the knowledge of an entity’s natural kind membership functions as the epistemic foundation for our inductive judgements about it: in virtue of knowing the latter collection, we may become reliably informed about the constitution of former—that is, about the superficially accessible and typical features which generally characterise it as a member of that kind.⁹

1.2 Natural Kind Essentialism

Much has been said concerning the philosophical theory of natural kinds without having mentioned the conceptual addendum of essentialism, even though it is relatively rare, in the contemporary literature at least, that any philosopher support or veto the theory without it.¹⁰ This has not been by accident, as I think it worth drawing out the commitments of the simple theory of realism about ‘natural kinds’ before examining it in the context of essentialism, however tightly these two are now bound up, as it is op...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Contents
• Acknowledgements
• List of Figures
• Introduction
• 1 Biological Natural Kind Essentialism: Definitions and Desiderata
• 2 Essence and Explanation: Natural Kinds in the Taxonomic Tree
• 3 Powerfully Directed Development: A Dispositional Analysis of Ontogenesis
• 4 Ontogenetic Causal Primacy: The Fount and Flow of Information
• 5 The Essence of Natural Kinds: Unity in Diversity
• 6 An Evolutionary Ontology: Priority, Modality, and the Natural State
• Conclusion
• Index