Integration (interaction among parts of an entity) is suggested to be necessary for individuality (contra, Metaphysics and the Origin of Species). A synchronic species is an integrated individual that can evolve as a unified whole; a diachronic lineage is a non-integrated historical entity that cannot evolve. Synchronic species and diachronic lineages are consequently suggested to be ontologically distinct entities, rather than alternative perspectives of the same underlying entity (contra Baum (1998), Syst. Biol. 47, 641–653; de Queiroz (...) (1995), Endless Forms: Species and Speciation, pp. 57–75; Genes, Categories and Species). Species concepts usually refer to either one or the other entity; for instance, the Biological Species Concept refers to synchronic species, whereas the Cladistic Species Concept refers to diachronic lineages. The debate over species concepts has often failed to recognise this distinction, resulting in invalid comparisons between definitions that attempt to delineate fundamentally different entities. (shrink)

The term ‘homology’ is persistently polysemous, defying the expectation that extensive scientific research should yield semantic stability. A common response has been to seek a unification of various prominent definitions. This paper proposes an alternative strategy, based on the insight that scientific concepts function as tools for research: When analyzing various conceptualizations of homology, we should preserve those distinguishing features that support particular research goals. We illustrate the fruitfulness of our strategy by application to two cases. First, we revisit E. (...) Ray Lankester’s celebrated (1870) evolutionary reappraisal of homology and argue that his analysis has been distorted by assimilation to modern agendas. His ‘homogeny’ does not mean the same thing as modern evolutionary ‘homology,’ and his ‘homoplasy’ is no mere antonym. Instead, Lankester uses both new terms to pose a question that remains strikingly relevant—how do mechanistic and historical causes of morphological resemblance interact? Second, we examine the puzzle of avian digit homology, which exemplifies disciplinary differences in homology conceptualization and assessment. Recent progress has been fueled by the development of new tools within the relevant disciplines (paleontology and developmental biology) and especially by increasing interdisciplinary cooperation. Conceptual unification has played very little role in this work, which instead seeks concrete evolutionary scenarios that integrate all the available evidence. Together these cases indicate the complex relationship between concepts and other tools in homology research. (shrink)

The conceptual dilemma that species entail has divided, since its formulation, biologists and philosophers in two spheres: those who believe in the existence of a unified category of species and those who defend the unyielding plurality of equally legitimate concepts. The aim of this paper is to comprise the analysis of the problems that revolve around the species category with the only purpose being to determine the existence of only one univocal and unrestricted definition of (...) class='Hi'>species. For this reason, the paper will be divided into two sections. The first section will analyse the extent to which essentialism amounts to an antithetical theory to the modern biological theory. In the second section a detailed critique will be carried out on existing attempts to devise a definition of species. Two conclusions can be drawn from the previous statements. First and due to the fall of essentialism, that there is not only one single category of species but an uncompromising plurality of concepts. Secondly and following previous assertion, it can be stated that the most consistent viewpoint in the evolutionary theory is the one in which an ontological pluralism is embraced and, consequently, a taxonomical pluralism. (shrink)

The conceptual dilemma that species entail has divided, since its formulation, biologists and philosophers in two spheres: those who believe in the existence of a unified category of species and those who defend the unyielding plurality of equally legitimate concepts. The aim of this paper is to comprise the analysis of the problems that revolve around the species category with the only purpose being to determine the existence of only one univocal and unrestricted definition of (...) class='Hi'>species. For this reason, the paper will be divided into two sections. The first section will analyse the extent to which essentialism amounts to an antithetical theory to the modern biological theory. In the second section a detailed critique will be carried out on existing attempts to devise a definition of species. Two conclusions can be drawn from the previous statements. First and due to the fall of essentialism, that there is not only one single category of species but an uncompromising plurality of concepts. Secondly and following previous assertion, it can be stated that the most consistent viewpoint in the evolutionary theory is the one in which an ontological pluralism is embraced and, consequently, a taxonomical pluralism. (shrink)

There are a number of different species concepts currently in use. The variety results from differing desiderata and practices of taxonomists, ecologists and evolutionary theorists. Recently, arguments have been presented for pluralism about species. I believe this is unsatisfactory, however, because of the central role of species in biological theory. Taking the line that species are individuals, I ask what might individuate them. In other work I have argued that dynamical systems are individuated by their cohesion. (...) I present here a version of a cohesion concept of species that accounts for the advantages of other species concepts, and is open-ended enough to accommodate additions to or changes in biological theory. On my account biological forces combine like Newtonian forces, to work on a common locus. Just as we might have an electromagnetic system, we might have an ecological species, if the dominant source of cohesion is ecology, but there is no certainty that biological species will divide up into elegant single principle types anymore than there is for physical systems. (shrink)

Ernst Mayr played a central role in the establishment of the general concept of species as metapopulation lineages, and he is the author of one of the most popular of the numerous alternative definitions of the species category. Reconciliation of incompatible species definitions and the development of a unified species concept require rejecting the interpretation of various contingent properties of metapopulation lineages, including intrinsic reproductive isolation in Mayr's definition, as necessary properties of (...) class='Hi'>species. On the other hand, the general concept of species as metapopulation lineages advocated by Mayr forms the foundation of this reconciliation, which follows from a corollary of that concept also advocated by Mayr: the proposition that the species is a fundamental category of biological organization. Although the general metapopulation lineage species concept and Mayr's popular species definition are commonly confused under the name "the biological species concept," they are more or less clearly distinguished in Mayr's early writings on the subject. Virtually all modern concepts and definitions of the species category, not only those that require intrinsic reproductive isolation, are to be considered biological according to the criterion proposed by Mayr. Definitions of the species category that identify a particular contingent property of metapopulation lineages (including intrinsic reproductive isolation) as a necessary property of species reduce the number of metapopulation lineages that are to be recognized taxonomically as species, but they cause conflicts among alternative species definitions and compromise the status of the species as a basic category of biological organization. (shrink)

Species pluralism gives us reason to doubt the existence of the species category. The problem is not that species concepts are chosen according to our interests or that pluralism and the desire for hierarchical classifications are incompatible. The problem is that the various taxa we call 'species' lack a common unifying feature.

This paper isolates a hard, long-standing species problem: developing a comprehensive and exacting theory about the constitutive conditions of the species category, one that is accurate for most of the living world, and which vindicates the widespread view that the species category is of more theoretical import than categories such as genus, sub-species, paradivision, and stirp. The paper then uncovers flaws in several views that imply we have either already solved that hard species problem or (...) dissolved it altogether – so-called We Are Done views. In doing so the paper offers new criticisms of the general lineage species concept (GLSC), evolutionary species concept (EvSC), biological species concept (BSC), other similar concepts, Ereshefsky’s eliminative pluralism about the species category, and both Mishler’s pessimism and Wilkins’ phenomenalism about that category. Opposed to We Are Done views, the paper argues for a Revving Up view, on which we are nearly ready to begin the hard species problem in earnest. To help work towards these conclusions, the paper begins with an outline of a new kind of view of species (Barker 2019a), which proposes they are feedback systems of a mathematically specifiable and empirically testable sort. (shrink)

Marc Ereshefsky’s project of eliminative pluralism holds that, as there is no unifying feature among all species concepts, we ought to doubt the existence of the species category. Here, I argue that one promising strategy for saving the species category is to reframe it as a natural kind after the practice turn. I suggest situating the species category within a recent account of natural kinds proposed by Marc Ereshefsky and Thomas Reydon called “scientific kinds”. Scientific kinds (...) highlight ontological boundaries. More importantly, they recognize boundaries drawn from the lab and the field, not only from the armchair. The point of this exercise is to situate the species category within an account of natural kinds that is sensitive to scientific practice. In order to argue for a realist interpretation of the species category, and not merely a pragmatic one, I rely on an approach to scientific metaphysics from Ken Waters that shifts the attention from “theory focused” to “practice-centered” analysis. (shrink)

It is common practice in formal semantics to assume that the context specifies an assignment of values to variables and that the same variables that receive contextually salient values when they occur free may also be bound by quantifiers and λs. These assumptions are at work to provide a unified account of free and bound uses of third person pronouns, namely one by which the same lexical item is involved in both uses. One way to pursue this account is (...) to treat quantifiers and λs as monsters in Kaplan’s sense. We argue that this move should be avoided and explore an alternative route based on the idea that there is a variable assignment coordinate in the context and a variable assignment coordinate in the circumstance of evaluation, with the definition of truth in context identifying them. One fundamental challenge that arises in pursuing a unified account is to explain the difference in the way the gender presuppositions of bound and free pronouns project. The proposal that emerges from the attempt to meet this challenge is a non-indexical account of free third person pronouns and a new conception of the role and structure of assignment functions. (shrink)

Lists of species underpin many fields of human endeavour, but there are currently no universally accepted principles for deciding which biological species should be accepted when there are alternative taxonomic treatments (and, by extension, which scientific names should be applied to those species). As improvements in information technology make it easier to communicate, access, and aggregate biodiversity information, there is a need for a framework that helps taxonomists and the users of taxonomy decide which taxa and names (...) should be used by society whilst continuing to encourage taxonomic research that leads to new species discoveries, new knowledge of species relationships, and the refinement of existing species concepts. Here, we present 10 principles that can underpin such a governance framework, namely (i) the species list must be based on science and free from nontaxonomic considerations and interference, (ii) governance of the species list must aim for community support and use, (iii) all decisions about list composition must be transparent, (iv) the governance of validated lists of species is separate from the governance of the names of taxa, (v) governance of lists of accepted species must not constrain academic freedom, (vi) the set of criteria considered sufficient to recognise species boundaries may appropriately vary between different taxonomic groups but should be consistent when possible, (vii) a global list must balance conflicting needs for currency and stability by having archived versions, (viii) contributors need appropriate recognition, (ix) list content should be traceable, and (x) a global listing process needs both to encompass global diversity and to accommodate local knowledge of that diversity. We conclude by outlining issues that must be resolved if such a system of taxonomic list governance and a unified list of accepted scientific names generated are to be universally adopted. (shrink)

This article examines the critique of the biological species concept advanced by protozoan geneticist Tracy Sonneborn at the 1955 AAAS symposium on "the species problem," published subsequently in 1957. Although Sonneborn was a strong proponent of a population genetical conception of species, he became critical of the biological species concept for its failure to incorporate asexual and obligatory inbreeding organisms. It is argued that Sonneborn's intimate knowledge of the ciliate protozoan Paramecium aurelia species (...) complex brought him into conflict with a growing pressure in the biological sciences to emphasize universal principles of life. Faced with the need to defend the value of P. aurelia as an investigative tool, Sonneborn argued that the sharp break in nature between sexual and asexual organisms posited by proponents of the biological species concept was not an existential feature of the living world, but rather the misleading consequence of an operational definition of species based only upon sexual organisms. Drawing upon his knowledge of the immense variability of P. aurelia, he proposed instead a continuum of breeding systems from obligatory outbreeding to asexual organisms, and a more broadly unifying definition of species that incorporated asexual as well as sexual organisms. Paradoxically, the push for unification that then characterized the evolutionary synthesis served to debar critical consideration of Sonneborn's more unificatory alternative, and his underlying contention that biological anomaly could serve as an important source of conceptual unification. (shrink)

Extinction is a concept of rapidly growing importance, with the world currently in the sixth mass extinction event and a biodiversity crisis. However, the concept of extinction has itself received surprisingly little attention from philosophers. I will first argue that in practice there is no single unified concept of extinction, but instead that its usage divides between descriptive, epistemic, and declarative concepts. I will then consider the epistemic challenges that arise in ascertaining whether a species (...) has gone extinct, and how these lead to serious limitations on responsibility and accountability for preventing extinctions. I will propose two conceptual engineering changes to our understanding of extinction. Firstly, to use twin epistemic concepts of extinction, corresponding to high and low epistemic demands. Secondly, to explicitly recognize that in many contexts extinction is a thick concept that contains an evaluative component, which therefore motivates explicit ethical considerations such as the use of precautionary principles. (shrink)

Sound is an inherent component of the environment that provides conditions and information necessary for many animal activities. Soniferous species require specific acoustic and physical conditions suitable for their signals to be transmitted, received, and effectively interpreted to successfully identify and utilize resources in their environment and interact with conspecifics and other heterospecific organisms. We propose the Acoustic Habitat Hypothesis to explain how the acoustic environment influences habitat selection of sound-dependent species. We postulate that sound-dependent species select (...) and occupy habitats with unique acoustic characteristics that are essential to their functional needs and conducive to the threshold of sound frequency they produce and detect. These acoustic habitats are based on the composition of biophony, geophony, and technophony in the soundscape and on the biosemiotics mechanisms described in the eco-field hypothesis. The Acoustic Habitat Hypothesis initiates questions of habitat selection that go beyond the physical attributes of the environment by applying ecoacoustics theory. We outline the theoretical basis of the Acoustic Habitat Hypothesis and provide examples from the literature to support its assumptions. The concept of acoustic habitats has been documented in the literature for many years but here, we accurately and extensively define acoustic habitat and we put this concept into a unified theory. We also include perspectives on how the Acoustic Habitat Hypothesis can stimulate a paradigm shift in conservation strategies for threatened and endangered species. (shrink)

Frank E. Zachos offers a comprehensive review of one of today's most important and contentious issues in biology: the species problem. After setting the stage with key background information on the topic, the book provides a brief history of species concepts from antiquity to the Modern Synthesis, followed by a discussion of the ontological status of species with a focus on the individuality thesis and potential means of reconciling it with other philosophical approaches. More than 30 different (...) species concepts found in the literature are presented in an annotated list, and the most important ones, including the Biological, Genetic, Evolutionary and different versions of the Phylogenetic Species Concept, are discussed in more detail. Specific questions addressed include the problem of asexual and prokaryotic species, intraspecific categories like subspecies and Evolutionarily Significant Units, and a potential solution to the species problem based on a hierarchical approach that distinguishes between ontological and operational species concepts. A full chapter is dedicated to the challenge of delimiting species by means of a discrete taxonomy in a continuous world of inherently fuzzy boundaries. Further, the book outlines the practical ramifications for ecology and evolutionary biology of how we define the species category, highlighting the danger of an apples and oranges problem if what we subsume under the same name ("species") is in actuality a variety of different entities. A succinct summary chapter, glossary and annotated list of references round out the coverage, making the book essential reading for all biologists looking for an accessible introduction to the historical, philosophical and practical dimensions of the species problem. (shrink)

A plethora of normative conservation concepts have recently emerged, most of which are ill-defined: biological diversity, biological integrity, ecological restoration, ecological services, ecological rehabilitation, ecological sustainability, sustainable development, ecosystem health, ecosystem management, adaptive management, and keystone species are salient among them. These normative concepts can be organized and interpreted by reference to two new schools of conservation philosophy, compositionalism and functionalism. The former comprehends nature primarily by means of evolutionary ecology and considers Homo sapiens separate from nature. The latter (...) comprehends nature primarily by means of ecosystem ecology and considers Homo sapiens a part of nature. Biological diversity, biological integrity, and ecological restoration belong primarily in the compositionalist glossary; the rest belong primarily in the functionalist glossary. The former set are more appropriate norms for reserves, the latter for areas that are humanly inhabited and exploited. In contrast to the older schools of conservation philosophy, preservationism and resourcism, compositionalism and functionalism are complementary, not competitive and mutually exclusive. As the historically divergent ecological sciences—evolutionary ecology and ecosystem ecology—are increasingly synthesized, a more unified philosophy of conservation can be envisioned. (shrink)

This article attempts a new interpretation of Lao Tzu's metaphysics of Tao by employing a combined method of linguistic and philosophical analyses. This new methodological approach involves the following basic assumptions: (1) Lao Tzu's metaphysics of Tao can be characterized as a kind of non?dualistic and non?conceptual metaphysics sub specie aeternitatis; (2) Tao is not an entity, substance, God, Idee, or anything hypostatized or conceptualized, but is rather a metaphysical symbol unifying various dimensions of Nature as the totality of things?as?they?are; (...) (3) there is, generally speaking, no confusion or inconsistency of thought involved in the Lao?Tzu; (4) there are two kinds of speech used by Lao Tzu, viz. philosophical (real) speech and figurative (metaphorical) speech; and (5) figurative expressions, which predominate, can be reduced to philosophical expressions for the sake of the clarification of Lao Tzu's thought. In the light of these basic assumptions, a philosophical explication of Lao Tzu's conception of Tao is undertaken by exploring its six dimensions. They are: (i) Tao as Reality, (ii) Tao as Origin, (iii) Tao as Principle, (iv) Tao as Function, (v) Tao as Virtue, and (vi) Tao as Technique; and (ii)?(vi) can be subsumed under Tao as Manifestation (to us). These six dimensions are not ?categories? or ?attributes? in the Western (conceptual) sense, but are the inseparable aspects or perspectives of Tao reconstructed from the Lao?Tzu in order to show the best possible way of understanding Lao Tzu's metaphysical thinking. In the Epilogue, a brief comparison of Lao Tzu and Spinoza is made in order to emphasize the non?conceptual and non?propositional nature of Lao Tzu's metaphysical language. (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)

Many phylogenetic systematists have criticized the Biological Species Concept (BSC) because it distorts evolutionary history. While defenses against this particular criticism have been attempted, I argue that these responses are unsuccessful. In addition, I argue that the source of this problem leads to previously unappreciated, and deeper, fatal objections. These objections to the BSC also straightforwardly apply to other species concepts that are not defined by genealogical history. What is missing from many previous discussions is the fact (...) that the Tree of Life, which represents phylogenetic history, is independent of our choice of species concept. Some species concepts are consistent with species having unique positions on the Tree while others, including the BSC, are not. Since representing history is of primary importance in evolutionary biology, these problems lead to the conclusion that the BSC, along with many other species concepts, are unacceptable. If species are to be taxa used in phylogenetic inferences, we need a history-based species concept. (shrink)

This chapter defends a pluralist understanding of species on which a normative species concept is viable and can support natural goodness evaluations. The central question here is thus: Since organisms are to be evaluated as members of their species, how does a proper understanding of species affect the feasibility of natural goodness evaluations? Philippa Foot has argued for a form of natural goodness evaluation in which living things are evaluated by how well fitted they are (...) for flourishing as members of their species, in ways characteristic of their species. She has further argued that assessments of moral goodness in humans are of the same evaluative form. However, natural goodness evaluations and, by extension, the natural goodness approach, do not garner justification in virtue of employing a scientifically privileged conception of species. The natural goodness approach is only justified given particular metaethical and normative commitments that are independent of naturalism, since the approach does not depend upon naturalism alone. (shrink)

The species concept is one of the oldest and most fundamental in biology. And yet it is almost universally conceded that no satisfactory definition of what constitutes a species has ever been proposed. The present article is devoted to an attempt to review the status of the problem from a methodological point of view. Since the species is one of the many taxonomic categories, the question of the nature of these categories in general needs to be (...) entered into. (shrink)

Species are the basis of the taxonomic scheme. They are the lowest taxonomic category that are used as units for describing biodiversity and evolution. In this contribution we discuss the current species concept for prokaryotes. Such organisms are considered to represent the widest diversity among living organisms. Species is currently circumscribed as follows: A prokaryotic species is a category that circumscribes a (preferably) genomically coherent group of individual isolates/strains sharing a high degree of similarity in (...) (many) independent features, comparatively tested under highly standardized conditions. Although the number of described prokaryotic species is underrepresented in the living world, this phylo-phenetic or polythetic species concept currently in use is considered to be pragmatic, operational and universally applicable and successfully used for identification processes. (shrink)

The nature of science is a primary goal in school science. Most teachers are not well-prepared for teaching NOS, but a sophisticated and in-depth understanding of NOS is necessary for effective teaching. Some authors emphasize the need for teaching NOS in context. Species, a central concept in biology, is proposed in this article as a concrete example of a means for achieving increased understanding of NOS. Although species are commonly presented in textbooks as fixed entities with a (...) single definition, the concept of species is a highly discussed one in the science and the philosophy of biology. A multitude of species concepts exist, reflecting both the views and interests of researchers and their utility in different organism groups. The present study serves to address the following questions: How do textbooks in Norwegian primary and lower secondary schools present the concept of species? Can inquiries into the concept of “species” serve to highlight aspects of NOS? A review of the available literature on species and species concepts in school is also performed. In the schoolbooks, the biological species concept is commonly used as the main definition, whereas the morphological species concept is represented by additional remarks of similarity. The potential and pitfalls of using the species concept for teaching NOS are discussed, with NOS being discussed both as a family resemblance concept and as a consensus list. Teacher education is proposed as a starting point for inducing a more sophisticated view of biology into schools. (shrink)

Students of later medieval semantics are familiar with the controversy that developed at the end of the thirteenth century over the signification of names. The debate focused on the signification of common nouns such as ‘man’ and ‘animal’: Do they signify an extramental thing or a mental representation of an extramental thing?Some authors at the end of the thirteenth century also discussed another question concerning what names signify, that is, whether they signify the composite of matter and form or only (...) the form of the composite. This second debate will not be considered in this article. Duns Scotus is commonly recognized as having played an important role in this debate.See Costantino Marmo, “Ontology and Semantics in the Logic of Duns Scotus,” in Umberto Eco and Costantino Marmo, ed., On Medieval Theory of Signs, (Amsterdam and Philadelphia: John Benjamins, 1989), pp. 161–63; and esp. Dominik Perler, “Duns Scotus on Signification,” Medieval Philosophy and Theology 3 (1993): 97–120. On the topic in general, see Paul Vincent Spade, “The Semantics of Terms,” in N. Kretzmann, A. Kenny, J. Pinborg, eds., The Cambridge History of Later Medieval Philosophy (Cambridge: Cambridge U.P., 1982), pp. 188–90; Jan Pinborg, “Bezeichnung in der Logik des XIII. Jahrhunderts,” in Albert Zimmermann, ed., Der Begriff der Repraesentatio im Mittelalter, Miscellanea Mediaevalia 8 (Berlin and New York: de Gruyter, 1971): 238–81; Elizabeth J. Ashworth, “Signification and Modes of Signifying in Thirteenth-Century Logic: A Preface to Aquinas on Analogy,” Medieval Philosophy and Theology 1 (1991): 43–53; Claude Panaccio, “From Mental Word to Mental Language,” Philosophical Topics 20 (1992): 125–47. In his Ordinatio, he alludes to a magna altercatio among his contemporaries concerning signification.John Duns Scotus, Ordinatio 1.27.1–3 n.83, in Commissio Scotistica, ed, Opera omnia 6 (Vatican City: Typis Polyglottis, 1963), p. 97. What is more, he gives, in his two commentaries on Aristotle’s Peri hermeneias, a detailed and fair analysis of the two contrasting positions on this issue.John Duns Scotus, Super Peri hermeneias 1.2, and Super Peri hermeneias 2.1, in Opera omnia 1 (Paris: L. Vivès, 1891), pp. 540–44, 582–85. Scotus’s logical commentaries are usually thought to have been composed before his theological writings, in the last decade of the thirteenth century. (shrink)

Species are the basis of the taxonomic scheme. They are the lowest taxonomic category that are used as units for describing biodiversity and evolution. In this contribution we discuss the current species concept for prokaryotes. Such organisms are considered to represent the widest diversity among living organisms. Species is currently circumscribed as follows: A prokaryotic species is a category that circumscribes a (preferably) genomically coherent group of individual isolates/strains sharing a high degree of similarity in (...) (many) independent features, comparatively tested under highly standardized conditions. Although the number of described prokaryotic species is underrepresented in the living world, this phylo-phenetic or polythetic species concept currently in use is considered to be pragmatic, operational and universally applicable and successfully used for identification processes. (shrink)

The idea that in human history it is possible to recognize distinct ways of thinking is widespread in the literature. Sometimes, instead of the phrase ‘ways of thinking’, other labels are used, such as ‘forms of thought’, ‘modes of thinking’, ‘ways of knowing’, ‘ways of reasoning’, ‘mental attitudes’ or ‘worldviews’. At any rate, it is possible to say that there is a concept, that of ‘ways of thinking’, which has played a crucial role in philosophy at least since the (...) Enlightenment and has acquired considerable weight with the emergence of a French tradition in philosophy of science called historical epistemology. This concept appears in different versions, as if they were species of the same genus. In this chapter, I shall outline its history, from Vico to Hacking and beyond, and I shall show how and why its different species have been introduced. My account provides a guiding thread running through philosophy of science that unifies the researches of important authors such as Lévy-Bruhl, Brunschvicg, Metzger, Koyré, Fleck, Foucault, Kuhn, Hacking and others. This guiding thread is mainly constituted by the project of historicizing Kant’s a priori by replacing it with a given notion of ‘ways of thinking’. (shrink)

The concept of individuality as applied to species, an important advance in the philosophy of evolutionary biology, is nevertheless in need of refinement. Four important subparts of this concept must be recognized: spatial boundaries, temporal boundaries, integration, and cohesion. Not all species necessarily meet all of these. Two very different types of pluralism have been advocated with respect to species, only one of which is satisfactory. An often unrecognized distinction between grouping and ranking components of (...) any species concept is necessary. A phylogenetic species concept is advocated that uses a grouping criterion of monophyly in a cladistic sense, and a ranking criterion based on those causal processes that are most important in producing and maintaining lineages in a particular case. Such causal processes can include actual interbreeding, selective constraints, and developmental canalization. The widespread use of the biological species concept is flawed for two reasons: because of a failure to distinguish grouping from ranking criteria and because of an unwarranted emphasis on the importance of interbreeding as a universal causal factor controlling evolutionary diversification. The potential to interbreed is not in itself a process; it is instead a result of a diversity of processes which result in shared selective environments and common developmental programs. These types of processes act in both sexual and asexual organisms, thus the phylogenetic species concept can reflect an underlying unity that the biological species concept can not. (shrink)

Summary The common view has been that Darwin regarded species as artificial and arbitrary constructions of taxonomists, not as distinct natural units. However, in his transmutation notebooks he clearly subscribed to the reality of species, on the basis of the criterion of non-interbreeding. A consequence of this biological species concept was his identification of the acquisition of reproductive isolation as the mark of the completion of speciation. He developed in the notebooks a theory of geographic speciation (...) on the grounds of (a) an empirical correlation between barriers and the geographical distributions of allied species, (b) the analogy of artificial isolation in the formation of new domesticated varieties, and (c) the logical consequence of blending inheritance. A brief discussion of Darwin's species concept in later writings concludes the paper. (shrink)

The biological species (biospecies) concept applies only to sexually reproducing species, which means that until sexual reproduction evolved, there were no biospecies. On the universal tree of life, biospecies concepts therefore apply only to a relatively small number of clades, notably plants andanimals. I argue that it is useful to treat the various ways of being a species (species modes) as traits of clades. By extension from biospecies to the other concepts intended to capture the (...) natural realities of what keeps taxa distinct, we can treat other modes as traits also, and so come to understand that theplurality of species concepts reflects the biological realities of monophyletic groups.We should expect that specialists in different organisms will tend to favour those concepts that best represent the intrinsic mechanisms that keep taxa distinct in their clades. I will address the question whether modes ofreproduction such as asexual and sexual reproduction are natural classes, given that they are paraphyletic in most clades. (shrink)

The longstanding species problem in biology has a history that suggests a solution, and that history is not the received history found in many texts written by biologists or philosophers. The notion of species as the division into subordinate groups of any generic predicate was the staple of logic from Aristotle through the middle ages until quite recently. However, the biological species concept during the same period was at first subtly and then overtly different. Unlike the (...) logic sense, which relied on definitions of the essence of both genus and species, biological species from the time of Epicurus were consistently considered to involve a reproductive element: in short, living species relied not on essential definitions, but on the generative cause, which might not be definable. I term this the generative conception of species: species were the generation by reproduction of form. This undercuts the claim that species before Darwin were essentialist, and divorces the notion of a type from that of essence. In fact, as late as the end of the nineteenth century, logicians explicitly treated biological “species” as a homonym only of logical essentialist species, and permitted considerable deviation from the type or form. At every point, species in logic were thought to be a subset, in effect, of some more general notion. I sketch a history of both philosophical and biological traditions of the species concept, before turning to the current conceptions. These are reconsidered in the light of this history, and in particular Mayr’s changing views are shown to be somewhat Whiggish, historiographically. Of the many touted biological species concepts, only one of which (Mayr’s) is called _the_ Biological Species Concept, none appears to capture all the relevant facts, intuitions, and operational requirements of biology. Cladistic conceptions, however, have much in common with the older philosophical literature, in that the natural group of cladism is the clade, or monophyletic group. After considering the Individuality Thesis, and the metaphysics of species, we see that species are the most particular terminal taxa in a clade, and that they are “defined” in terms of the particular synapomorphies, or evolved characters, that are causally responsible for keeping the lineages that organisms form distinct from one another. In this way, we can remain within the generative conception of species that has been in play for over two millennia, and yet avoid the pitfalls of prior attempts to find a universal conception of species. (shrink)