This paper attempts to reconcile the conceptual conflict between typological and population thinking to provide a philosophical foundation for extended evolutionary synthesis. Typological thinking has been considered a pre-Darwinian, essentialist dogma incompatible with population thinking, which is the core notion of Darwinism. More recent philosophical and historical studies suggest that a non-essentialist form of typology has some advantages in the study of evolutionary biology. However, even if we adopt such an epistemological interpretation of typological thinking, there still remains an epistemological (...) and methodological conflict between these two styles of thinking. How can we relate typological thinking with population thinking in pursuit of more integrated or interconnected research into evolutionary biology? I propose that homology thinking, which is another style of thinking that recognizes homologous characters, provides a common basis for typological representations of character states and for character dynamics in an evolving population. Good examples of this bridging role are found in teratology and breeding, where variation and novelty are recognized in developmental and morphological traits, gene expression patterns, and so on. Essentialism-free, dynamic views of homology have great potential to reconcile typological and population thinking and to set the stage for the EES. (shrink)

Biological lineages move through time, space, and each other. As they do, they diversify, diverge, and grade away from and into one another. One result of this is genealogical discordance; i.e., the lineages of a biological entity may have different histories. We see this on numerous levels, from microbial networks, to holobionts, to population-level lineages. This paper considers how genealogical discordance impacts our study of species. More specifically, I consider this in the context of three framing questions: (1) How, if (...) at all, does genealogical discordance challenge, modify, or revise how we conceive of species? (2) How has growing appreciation of genealogical discordance impacted scientific practice? Of systematics in particular? (3) How do lineages at different levels diverge and diversify? All told, genealogical discordance enriches and complicates our taxonomic ontology, as well as the practice of reconstructing phylogenies. This presents both challenges and opportunities for the study of divergence and diversification. (shrink)

One of the purposes of the research program referred to as “systematic biogeography” is the use of species distributions to identify regions and reconstruct biotic area relationships. The reverse, i.e. to group species according to the areas that they live in, leads to the recognition of chorological categories. Biogeographers, working under these two different approaches, have proposed several terms to refer to groups of species that have similar distributions, such as “element”, “chorotype” and “component”. A historical reconstruction, including semantic observations (...) and philosophical implications, shows that these terms have been used in a variety of senses. The word “component” should not be used in biogeography. The word “element” has been used to identify both a group of species defined according to the biogeographic areas they occupy and a group of species with an assumed shared biogeographic history. It is especially because of the influence of the dispersalist paradigm, which dominated evolutionary thought until the mid-twentieth century, that the second definition has been frequently adopted. The term “element” is therefore ambiguous and its use should always be associated with an explicit definition. The word “chorotype” should be used to define groups of species with similar ranges when no causal assumption is made. The concept of “chorotype,” finally, should not be confounded with other concepts such as distributional pattern, cenocron, horofauna, biota, endemic area, area of endemism, biotic element, and generalized track, which are also discussed in this paper. (shrink)

Homology is a fundamental concept in biology. However, the metaphysical status of homology, especially whether a homolog is a part of an individual or a member of a natural kind, is still a matter of intense debate. The proponents of the individuality view of homology criticize the natural kind view of homology by pointing out that homologs are subject to evolutionary transformation, and natural kinds do not change in the evolutionary process. Conversely, some proponents of the natural kind view of (...) homology argue that a homolog can be construed both as a part of an individual and a member of a natural kind. They adopt the Homeostatic Property Cluster theory of natural kinds, and the theory seems to strongly support their construal. Note that this construal implies the acceptance of essentialism. However, looking back on the history of the concept of homology, we should not overlook the fact that the individuality view was proposed to reject the essentialist interpretation of homology. Moreover, the essentialist notions of natural kinds can, in our view, mislead biologists about the phenomena of homology. Consequently, we need a non-essentialist view of homology, which we name the “persistently reproducible module” view. This view highlights both the individual-like and kind-like aspects of homologs while stripping down both essentialist and anti-essentialist interpretations of homology. In this article, we articulate the PRM view of homology and explain why it is recommended over the other two views. (shrink)

Biological taxonomists rely on the so-called ‘type method’ to regulate taxonomic nomenclature. For each newfound taxon, they lay down a ‘type specimen’ that carries with it the name of the taxon it belongs to. Even if a taxon’s circumscription is unknown and/or subject to change, it remains a necessary truth that the taxon’s type specimen falls within its boundaries. Philosophers have noted some time ago that this naming practice is in line with the causal theory of reference and its central (...) notion of rigid designation: a type specimen fixes the reference of a taxon name without defining it. Recently, however, this consensus has come under pressure in the pages of this journal. In a series of articles by Alex Levine, Joseph LaPorte, and Matthew Haber, it has been argued that type specimens belong only contingently to their species, and that this may bode problems for the relation between type method and causal theory. I will argue that this ‘contingency debate’ is a debate gone wrong, and that none of the arguments in defense of contingency withstand scrutiny. Taxonomic naming is not out of step with the causal theory, but conforms to it. However, I will also argue that this observation is itself in need of further explanation, since application of the type method in taxonomic practice is plagued by errors and ambiguities that threaten it with breaking down. Thus, the real question becomes why taxonomic naming conforms to the causal theory in the first place. I will show that the answer lies in the embedding of the type method into elaborate codes of nomenclature. (shrink)

Homeostatic property clusters (HPCs) are offered as a way of understanding natural kinds, especially biological species. I review the HPC approach and then discuss an objection by Ereshefsky and Matthen, to the effect that an HPC qua cluster seems ill-fitted as a description of a polymorphic species. The standard response by champions of the HPC approach is to say that all members of a polymorphic species have things in common, namely dispositions or conditional properties. I argue that this response fails. (...) Instances of an HPC kind need not all be similar in their exhibited properties. Instead, HPCs should instead be understood as unified by the underlying causal mechanism that maintains them. The causal mechanism can both produce and explain some systematic differences between a kind’s members. An HPC kind is best understood not as a single cluster of properties maintained in stasis by causal forces, but as a complex of related property clusters kept in relation by an underlying causal process. This approach requires recognizing that taxonomic systems serve both explanatory and inductive purposes. (shrink)

Essentialism is widely regarded as a mistaken view of biological kinds, such as species. After recounting why (sections 2-3), we provide a brief survey of the chief responses to the “death of essentialism” in the philosophy of biology (section 4). We then develop one of these responses, the claim that biological kinds are homeostatic property clusters (sections 5-6) illustrating this view with several novel examples (section 7). Although this view was first expressed 20 years ago, and has received recent discussion (...) and critique, it remains underdeveloped and is often misrepresented by its critics (section 8). (shrink)

Species pluralism allows for multiple species concepts. Given the overwhelming number of such concepts, this seems like an obvious interpretation of how `species' is used in contemporary biology. But why has it taken so long for this approach to be considered? I argue that part of the reason pluralism was overlooked due to the widespread use of a particular rhetorical strategy developed by Ernst Mayr. This strategy provided a framework for debates about the correct conception of species. That is, the (...) strategy offered a means of comparing modern concepts with a monistic-essentialist understanding of species. I ask what would happen if we replaced this concept with Aristotle's own pluralist-essentialist understanding of species. As recent scholarship shows, Aristotle's philosophy of biology allows for an approach to classification that is in practice highly pluralistic. From this new framework we can understand what sort of assumptions are at stake between modern forms of species pluralism. My analysis shows that the essentialist story told by Mayr and others left us asking the wrong questions about how to conceive of species in an evolutionary world. Having a deeper understanding of Aristotle's approach to the classification of animals allows us to shift focus from the so-called species problem in order to raise four issues that are relevant to current debates. These are questions about: the explanatory power of taxonomic ranks, the importance of the species category problem, whether species are constituted by intrinsic or extrinsic properties, and how to interpret the ``cross-cutting'' metaphor endemic to the pluralist literature. In order to get to these questions I will first explain what sort of claim species pluralism is at the most general level, and a gloss on the standard interpretation of the historical shift from species monism to species pluralism. (shrink)

In Objectivity, Daston and Galison argue that scientific objectivity has a history. Objectivity emerged as a distinct nineteenth-century “epistemic virtue,” flanked in time by other epistemic virtues. The authors trace the origins of scientific objectivity by identifying changes in images from scientific atlases from different periods, but they emphasize that the same history could be narrated using different sorts of scientific objects. One could, for example, focus on the changing uses of “type specimens” in biological taxonomy. Daston :153–182, 2004) indeed (...) provides a detailed account of the history of the type specimen which purports to show this. I argue that this attempt hinges on a conceptual confusion and therefore fails. I show that the actual history of the type specimen does not reinforce the account of epistemic virtues from Objectivity, but rather threatens to subvert it. (shrink)

Despite the traditional focus on metaphysical issues in discussions of natural kinds in biology, epistemological considerations are at least as important. By revisiting the debate as to whether taxa are kinds or individuals, I argue that both accounts are metaphysically compatible, but that one or the other approach can be pragmatically preferable depending on the epistemic context. Recent objections against construing species as homeostatic property cluster kinds are also addressed. The second part of the paper broadens the perspective by considering (...) homologues as another example of natural kinds, comparing them with analogues as functionally defined kinds. Given that there are various types of natural kinds, I discuss the different theoretical purposes served by diverse kind concepts, suggesting that there is no clear-cut distinction between natural kinds and other kinds, such as functional kinds. Rather than attempting to offer a unique metaphysical account of ‘natural’ kind, a more fruitful approach consists in the epistemological study of how different natural kind concepts are employed in scientific reasoning. (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)

Michael and has argued that species have intrinsic essences. This paper rebuts Devitt’s arguments, but in so doing it shores up the anti-essentialist consensus in two ways that have more general interest. First, species membership can be explanatory even when species have no essences; that is, Tamsin’s membership of the tiger species can explain her stripyness, without this committing us to any further claim about essential properties of tigers. Second, even the views of species that appear most congenial to essentialism—namely (...) phenetic and genotypic cluster accounts—do not entail strong forms of intrinsic essentialism. (shrink)

Type specimens are used to designate species. What is the nature of the relation between a type specimen and the species it designates? If species names are rigid designators, and type specimens ostensively define species, then that relation is, at the very least, a close one. Levine :325–338, 2001) argues that the relationship of type specimen to a named species is one of necessity—and that this presents problems for the individuality thesis. Namely, it seems odd that a contingently selected specimen (...) should belong to a species of necessity. In considering Levine’s argument, LaPorte suggests that recognizing the distinction between de re and de dicto necessity resolves Levine’s worries. I reconsider the motivating question: does a type specimen belong of necessity to the species that it designates? In light of taxonomic cases and practice the answer is clear: definitively not. This is particularly clear in the case of re-designation of types by taxonomic decree. I explain how this helps reveal how taxonomists prioritize competing theoretical commitments, and offer a defense of the individuality thesis as applied to these particular cases. In short, I demonstrate how to misidentify a type specimen. (shrink)

This article argues for a different outlook on the concept of extension, especially for the reference of general terms in scientific practice. Scientific realist interpretations of the two predominant theories of meaning, namely Descriptivism and Causal Theory, contend that a stable cluster of descriptions or an initial baptism fixes the extension of a general term such as a natural kind term. This view in which the meaning of general terms is presented as monosemantic and the referents as stable, homogeneous, and (...) unchangeable, however, does not reflect the various practices involved in the investigation of research materials and the related application of general terms in scientific practice. By drawing on the taxonomic diversity, particularly of structure-based classifications in chemical databases, this article illustrates the limited utility of such a concept of extension. Research materials often exhibit a plurality of material dimensions that, within different research contexts, allow for various and often equally significant taxonomic demarcations. In light of this, the extension of a general term cannot be uniquely determined by a supposedly independent nature of the referent but is relative to the model context under which the materials are investigated. This significance and plurality of the model context, I claim, needs to be mirrored in an account of meaning that is supposed to reflect scientific reality. On this account, the aim of this article is to present an alternative perspective on the concept of extension to accommodate the diverse material practices that determine the application of general terms in science. (shrink)