Realist philosophies of science posit a dialectical relation between theoretical, explanatory knowledge and practical, including taxonomic knowledge. This paper examines the dialectic between the theory of descent and empirical, Linnaean taxonomy which is based on a logic of traditional classes. It considers the arguments of David Hull to the effect that many of the practical problems of empirical classification can be resolved by means of an ontology based upon the theory of descent in which species taxa are regarded as individuals (...) rather than as classes or natural kinds.Contra Hull, it is argued that this view is, at best, only partially consistent with taxonomic practice and that it cannot sustain experimental practice which presupposes that species taxa be regarded as natural kinds. An outline is given of a possible alternative dialectic between a field theory of morphogenesis and a rational systematics involving a logic of relations. (shrink)

Various philosophers and evolutionary biologists have recently defended the thesis that species are individuals rather than sets. A decade of debates, however, did not suffice to settle the matter. Conceptual analysis shows that many of the key terms involved are ambiguous. Current disagreements should dissolve once this is recognized. Explication of the concepts involved leads to new programs for philosophical research. It could also help biology by showing how extant controversies concerning evolution may have conceptual rather than factual roots.

The purpose of this paper is to test the contemporary concept of biological species against some of the problems caused by treating species as spatiotemporally extended entities governed by criteria of persistence, identity, etc. After outlining the general problem of symmetric division in natural objects, I set out some useful distinctions (section 1) and confirm that species are not natural kinds (section 2). Section 3 takes up the separate issue of species definition, focusing on the Biological Species Concept (BSC). Sections (...) 4 and 5 examine the matter of species identity over space and time respectively, as determined by the BSC. Both gradualistic and punctuated equilibrium models of speciation are discussed. In section 6 I argue that the BSC fails to determine adequate criteria for dealing with certain kinds of speciation. Section 7 moves speculatively beyond the BSC to a brief examination of alternatives. (shrink)

A number of influential biologists are currently pursuing efforts to restore previously extinct species. But for decades, philosophers of biology have regarded “de-extinction” as conceptually incoherent. Once a species is gone, it is gone forever. We argue that a range of metaphysical, biological, and ethical grounds for opposing de-extinction are at best inconclusive and that a pragmatic stance that allows for its possibility is more appealing.

Species in biology are traditionally perceived as kinds of organisms about which explanatory and predictive generalizations can be made, and biologists commonly use species in this manner. This perception of species is, however, in stark contrast with the currently accepted view that species are not kinds or classes at all, but individuals. In this paper I investigate the conditions under which the two views of species might be held simultaneously. Specifically, I ask whether upon acceptance of an ontology of species (...) as diachronic segments of the tree of life species can perform the epistemic role of kinds of organisms to which explanatory and predictive generalizations apply. I show that, for species-level segments of the tree of life, several requirements have to be met before the performance of this epistemic role is possible, and I argue that these requirements can be met by defining species according to the Composite Species Concept proposed by Kornet and McAllister in the 1990s. (shrink)

The circumscription of taxa and classification of organisms are fundamental tasks in the systematization of biological diversity. Their success depends on a unified idea concerning the species concept, evolution, and taxonomy; paradoxically, however, it requires a complete distinction between taxa and evolutionary units. To justify this view, I discuss these three topics of systematics. Species concepts are examined, and I propose a redefinition for the Taxonomic Species Concept based on nomenclatural properties, in which species are classes conventionally represented by a (...) binomial. Speciation is subsequently discussed, to demonstrate that concepts on the evolutionary process are damaged when species are considered as evolutionary units. Speciation should be considered a transition among patterns of a population and, consequently, always a sympatric process. This view contrasts with the majority of speciation models, which analyze cladogeneses and classify speciation geographically, usually considering allopatry the essential condition for the differentiation process. Finally, taxonomy is considered, to show that the equivalence between evolutionary and taxonomic units may also damage the practice of biological systematization. Principles and rules of nomenclature and classification should offer freedom to accommodate divergent opinions about systematics and to incorporate the evolution of knowledge; therefore, they should remain independent of biological theories. (shrink)

A system of environmental ethics recently developed by Lawrence Johnson may be used to analyze the moral implications of biological control. According to this system, entities are morally relevant when they possess well-being interests (i.e., functions or processes that can be better or worse in so far as the entity is concerned). In this formulation of ethical analysis, species and ecosystems are morally relevant because they are not simply aggregates of individuals, so their processes, properties, and well-being interests are not (...) reducible to the sum of their individual members. Following Johnson's thesis, species and ecosystems have morally relevant interests in surviving and maintaining themselves as integrated wholes with particular self-identities. This theoretical structure gives rise to a number of ethical criteria that are particularly relevant to biological control, which apply to the ecosystem (the extent to which it is large, native, unique, and integrated) and to the action being considered (the extent to which it is novel, omnipresent, monitored, reversible, and necessary). In these terms, it is evident that not all biological control efforts are ethically defensible. In general terms, natural biological control is most desirable, followed by augmentative strategies, classical approaches, and finally neoclassical biological control. Two specific cases (neoclassical biological control of rangeland grasshoppers and classical biological control of prickly pear cactus) illustrate the ethical concerns. Finally, it can be shown that formalized restrictions of biological control are necessary, given the unique properties of this technology. (shrink)

I defend a view of the species category, pluralistic realism, which is designed to do justice to the insights of many different groups of systematists. After arguing that species are sets and not individuals, I proceed to outline briefly some defects of the biological species concept. I draw the general moral that similar shortcomings arise for other popular views of the nature of species. These shortcomings arise because the legitimate interests of biology are diverse, and these diverse interests are reflected (...) in different legitimate approaches to the classification of organisms. In the final section, I show briefly how the pluralistic approach can help to illuminate some areas of biological and philosophical dispute. (shrink)

Future generations do not exist, and are not determinate in their make-up. The moral significance of future generations cannot be accounted for on the basis of a purely individualistic ethic. Yet future generations are morally significant. The Person-Affecting Principle, that (roughly) only acts which are likely to affect particular individuals are morally significant, must be augmented in such a way as to take into account the moral significance of Homo sapiens, a holistic entity which certainly does exist. Recent contributions to (...) Environmental Values by Alan Carter and Ernest Partridge are criticised (but not entirely rejected). (shrink)

Biologists and philosophers have long recognized the importance of species, yet species concepts serve two masters, evolutionary theory on the one hand and taxonomy on the other. Much of present-day evolutionary and systematic biology has confounded these two roles primarily through use of the biological species concept. Theories require entities that are real, discrete, irreducible, and comparable. Within the neo-Darwinian synthesis, however, biological species have been treated as real or subjectively delimited entities, discrete or nondiscrete, and they are often capable (...) of being decomposed into other, smaller units. Because of this, biological species are generally not comparable across different groups of organisms, which implies that the ontological structure of evolutionary theory requires modification. Some biologists, including proponents of the biological species concept, have argued that no species concept is universally applicable across all organisms. Such a view means, however, that the history of life cannot be embraced by a common theory of ancestry and descent if that theory uses species as its entities.These ontological and biological difficulties can be alleviated if species are defined in terms of evolutionary units. The latter are irreducible clusters of reproductively cohesive organisms that are diagnosably distinct from other such clusters. Unlike biological species, which can include two or more evolutionary units, these phylogenetic species are discrete entities in space and time and capable of being compared from one group to the next. (shrink)

This paper explains the metaphysical implications of the view that species are individuals (SAI). I first clarify SAI in light of the separate distinctions between individuals and classes, particulars and universals, and abstract and concrete things. I then show why the standard arguments given in defense of SAI are not compelling. Nonetheless, the ontological status of species is linked to the traditional "species problem," in that certain species concepts do entail that species are individuals. I develop the idea that species (...) names are rigid designators and show how this provides additional motivation for SAI. (shrink)

We attempt to defend the species-as-individuals hypothesis by examining the logical role played by the binomials (e.g., "Homo sapiens," "Pinus ponderosa") in biological discourse about species. Those who contend that the binomials can be properly understood as functioning in biological theory as singular terms opt for an objectual account of species and view species as individuals. Those who contend that the binomials can in principle be eliminated from biological theory in favor of predicate expressions opt for a predicative account of (...) species and view species as kinds. We contend that biologists' talk about species is talk about species as individuals, and we conclude that the most plausible account of species is an objectual account. (shrink)

This paper brings needed clarity to the influential view that species are cohesive entities held together by gene flow, and then develops an empirical argument against that view: Neglected data suggest gene flow is neither necessary nor sufficient for species cohesion. Implications are discussed. ‡I'm grateful to Rob Wilson, Alex Rueger and Lindley Darden for important comments on earlier drafts, and to Joseph Nagel, Heather Proctor, Ken Bond, members of the DC History and Philosophy of Biology reading group, and audience (...) members at the November 2006 meeting of the PSA, for helpful comments or discussion. Social Sciences and Humanities Research Council of Canada fellowship 752-2005-1208 supported research. †To contact the author, please write to: Philosophy Department, University of Wisconsin–Madison, 5185 Helen C. White Hall, 600 North Park Street, Madison, WI 53706; e-mail: [email protected]. (shrink)

The circumscription of taxa and classification of organisms are fundamental tasks in the systematization of biological diversity. Their success depends on a unified idea concerning the species concept, evolution, and taxonomy; paradoxically, however, it requires a complete distinction between taxa and evolutionary units. To justify this view, I discuss these three topics of systematics. Species concepts are examined, and I propose a redefinition for the Taxonomic Species Concept based on nomenclatural properties, in which species are classes conventionally represented by a (...) binomial. Speciation is subsequently discussed, to demonstrate that concepts on the evolutionary process are damaged when species are considered as evolutionary units. Speciation should be considered a transition among patterns of a population and, consequently, always a sympatric process. This view contrasts with the majority of speciation models, which analyze cladogeneses and classify speciation geographically, usually considering allopatry the essential condition for the differentiation process. Finally, taxonomy is considered, to show that the equivalence between evolutionary and taxonomic units may also damage the practice of biological systematization. Principles and rules of nomenclature and classification should offer freedom to accommodate divergent opinions about systematics and to incorporate the evolution of knowledge; therefore, they should remain independent of biological theories. (shrink)

Species are central to biology, but there is currently no agreement on what the adequate species concept should be, and many have adopted a pluralist stance: different species concepts will be required for different purposes. This thesis is a multidimensional analysis of species pluralism. First I explicate how pluralism differs monism and relativism. I then consider the history of species pluralism. I argue that we must re-frame the species problem, and that re-evaluating Aristotle's role in the histories of systematics can (...) shed light on pluralism. Next I consider different forms of pluralism: evolutionary and extra-evolutionary species pluralism, which differ in their stance on evolutionary theory. I show that pluralism is more than a debate about the species category, but a debate about which concepts are legitimate and a claim about how they interact with one another. Following that, I consider what sort of ontology is required for different forms of species pluralism. I argue that pluralists who deny the unity of biology will require a further plurality of frameworks, while those that ground their pluralism in evolution need only one framework. Finally, I consider what pluralism means for biological practice. I argue that species concepts are tools, and reflect on how pluralism can illuminate the way systematists approach the discovery of new species of yeast. Pluralism can make sense of the way species concepts are used, and can be developed to aid researchers in thinking about how to use the right tools for the right jobs. (shrink)