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The individuality thesis (3 ways)

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I spell out and update the individuality thesis, that species are individuals, and not classes, sets, or kinds. I offer three complementary presentations of this thesis. First, as a way of resolving an inconsistent triad about natural kinds; second, as a phylogenetic systematics theoretical perspective; and, finally, as a novel recursive account of an evolved character (individuality). These approaches do different sorts of work, serving different interests. Presenting them together produces a taxonomy of the debates over the thesis, and isolates ways it has been (and may continue to be) productive. This goes to the larger point of this paper: a defense of the individuality thesis in terms of its utility, and an update of it in light of recent theoretical developments and empirical work in biology.
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The individuality thesis (3 ways)
Matthew H. Haber
1
Published online: 25 October 2016
Springer Science+Business Media Dordrecht 2016
Abstract I spell out and update the individuality thesis, that species are individuals,
and not classes, sets, or kinds. I offer three complementary presentations of this
thesis. First, as a way of resolving an inconsistent triad about natural kinds; second,
as a phylogenetic systematics theoretical perspective; and, finally, as a novel
recursive account of an evolved character (individuality). These approaches do
different sorts of work, serving different interests. Presenting them together pro-
duces a taxonomy of the debates over the thesis, and isolates ways it has been (and
may continue to be) productive. This goes to the larger point of this paper: a defense
of the individuality thesis in terms of its utility, and an update of it in light of recent
theoretical developments and empirical work in biology.
Keywords Individuality Phylogenetics Systematics Natural kinds
Introduction
In the 1970’s Ghiselin (1974) and Hull (1976,1978) proposed the view that species
are individuals, and not abstract classes or kinds. This view has generated an
expansive literature in both biology and philosophy, and is typically referred to as
the individuality thesis.
In this paper I spell out and defend an updated account of the individuality thesis,
presenting it in three complementary ways. First, as a strategy for resolving an
inconsistent triad about natural kinds. This novel framing of a familiar character-
ization provides a clear taxonomy of an important line of debate, and provides an
&Matthew H. Haber
matt.haber@utah.edu
1
Department of Philosophy and Center for Quantitative Biology, University of Utah,
Salt Lake City, UT, USA
123
Biol Philos (2016) 31:913–930
DOI 10.1007/s10539-016-9548-9
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... One way to address borderline cases of species is to follow David Hull (1978) into thinking that species are 'lineage segments' in This paper is divided into two sections. The first section introduces the lineage-based view of biological individuality proposed by Haber (2016) and others. The second section applies this view of biological individuality to microbial groups that are formed via aggregation, such as slime molds and dental plaque. ...
... As Ereshefsky (2010) suggests, Hull's strategy for defining species might be called "individual thinking." 4 In fact, multiple authors have relied on D. L. Hull (1978) to propose that, in addition to species, other levels of the biological hierarchy should be viewed as biological individuals, such as higher taxa and organisms (e.g., Haber 2016;Eldredge 1985;Vrba and Eldredge 1984;D. Hull 1980). ...
... At first glance, the stochastic factor associated with aggregation seems to undercut Haber's (2016) suggestion that individual thinking can be fruitfully applied to microbial aggregates. However, there also exist examples of microbial communities that are formed by aggregation with cells that are highly genetically related. ...
Article
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Nature is replete with borderline cases that fall somewhere between organisms and communities. One broad class of borderline cases are microbial groups partially formed by the aggregation of cells from the environment, such as slime molds and dental plaque. Some have argued that microbial aggregates do not form lineages because microbial aggregates can acquire cells from the surrounding environment. Nevertheless, Haber (2016) has recently suggested that microbial aggregates may form lineages, but he does not fully elaborate his position. This paper argues that Haber’s suggestion is correct as long as a permissive criterion of what constitutes a ‘lineage-generating entity’ is adopted. Different mechanisms for lineage formation in microbial aggregates will be described to motivate this argument. Unlike mammals, lineage formation in microbial aggregates is more dependent on ecological factors and does not produce well-defined parent-offspring relations. Yet, focusing on the formation of incipient lineages has the benefit of improving our understanding of the processes that hold microbial aggregates together, and it helps bridge the gap between the literature on biological individuality and recent work on microbial communities.
... Some lineages have evolved the capacity to gain or lose parts more or less easily, which can be expressed and measured in terms of how closely constituent lineages track each other. Moreover, diachronic individuality itself (or, at least, biological part/whole relations) may be conceived of by degree, in terms of how tightly lineages concordantly recur-be it over ontogenetic (Pradeu 2012) or evolutionary (Haber 2016) time, or the intersection of those (Doolittle and Booth 2017). ...
... This suggests that the distinctiveness and discreteness of groups or levels of hierarchy is an evolved feature of biological hierarchies that might not be expressed uniformly across the entirety of biology. That is, 'species' as a level of lineage or group is an evolved character of biological lineages and clades (Haber 2016) (and, where that level did emerge, it may have done so in very different ways). Among other things, this supports a rank-free view of that hierarchy (G. ...
... These groups may fail to be natural kinds, 8 but that hardly means they are not theoretically relevant, causally efficacious, or explanatorily rich. It is, thus, a mistake to think that only groups that are natural kinds, or that present clean categorical boundaries, are groups worth tracking, naming, or classifying (e.g., G. C. D. Griffiths 1974;Gauthier 1986;Queiroz 2007;Ereshefsky 2007;Haber 2016). ...
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... If, as many have argued, pluralism about lineages is true and evolutionary independence comes in degrees, it should be expected that different operationalizations lead to different outcomes (Ereshefsky 1992;Degnan and Rosenberg 2006;Haber 2012;Maddison 1997). Indeed, as will become clear in the last section of the paper, understanding this may be epistemically valuable, for example when knowledge on the differences between various operationalizations can be implemented in species delimitation (Degnan and Rosenberg 2009;Haber 2016). However, even if this metaphysical picture holds, it remains the case that taxonomists have to get on with the task of recognising certain groups of organisms as species. ...
... By focusing on the epistemology of species delimitation rather than the metaphysical nature of species, this paper deviates from the largest part of the philosophical literature on species. Instead, it picks up on the research cited above which highlights the epistemological implications of our growing understanding of the nature of species Rosenberg 2006, 2009;Haber 2012Haber , 2016Maddison 1997;Sterner 2017). This paper advances such research by developing one particularly important epistemological problem in more detail (i.e., the POD) and proposing a potential solution. ...
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There is growing agreement among taxonomists that species are independently evolving lineages. The central notion of this conception, evolutionary independence, is commonly operationalized by taxonomists in multiple, diverging ways. This leads to a problem of operationalization-dependency in species classification, as species delimitation is not only dependent on the properties of the investigated groups, but also on how taxonomists choose to operationalize evolutionary independence. The question then is how the operationalization-dependency of species delimitation is compatible with its objectivity and reliability. In response to this problem, various taxonomists have proposed to integrate multiple operationalizations of evolutionary independence for delimiting species. This paper first distinguishes between a standard and a sophisticated integrative approach to taxonomy, and argues that it is unclear how either of these can support the reliability and objectivity of species delimitation. It then draws a parallel between the measurement of physical quantities and species delimitation to argue that species delimitation can be considered objective and reliable if we understand the sophisticated integrative approach as assessing the coherence between the idealized models of multiple operationalizations of evolutionary independence.
... If, as many have argued, pluralism about lineages is true and evolutionary independence comes in degrees, it should be expected that different operationalizations lead to different outcomes (Ereshefsky 1992;Degnan and Rosenberg 2006;Haber 2012;Maddison 1997). Indeed, as will become clear in the last section of the paper, understanding this may be epistemically valuable, for example when knowledge on the differences between various operationalizations can be implemented in species delimitation (Degnan and Rosenberg 2009;Haber 2016). However, even if this metaphysical picture holds, it remains the case that taxonomists have to get on with the task of recognising certain groups of organisms as species. ...
... By focusing on the epistemology of species delimitation rather than the metaphysical nature of species, this paper deviates from the largest part of the philosophical literature on species. Instead, it picks up on the research cited above which highlights the epistemological implications of our growing understanding of the nature of species Rosenberg 2006, 2009;Haber 2012Haber , 2016Maddison 1997;Sterner 2017). This paper advances such research by developing one particularly important epistemological problem in more detail (i.e., the POD) and proposing a potential solution. ...
Article
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There is growing agreement among taxonomists that species are independently evolving lineages. The central notion of this conception, evolutionary independence, is commonly operationalized by taxonomists in multiple, diverging ways. This leads to a problem of operationalization-dependency in species classification, as species delimitation is not only dependent on the properties of the investigated groups, but also on how taxonomists choose to operationalize evolutionary independence. The question then is how the operationalization-dependency of species delimitation is compatible with its objectivity and reliability. In response to this problem, various taxonomists have proposed to integrate multiple operationalizations of evolutionary independence for delimiting species. This paper first distinguishes between a standard and a sophisticated integrative approach to taxonomy, and argues that it is unclear how either of these can support the reliability and objectivity of species delimitation. It then draws a parallel between the measurement of physical quantities and species delimitation to argue that species delimitation can be considered objective and reliable if we understand the sophisticated integrative approach as assessing the coherence between the idealized models of multiple operationalizations of evolutionary independence.
... In the last four decades or so, especially after the founding work of David Hull, most of the debates about biological individuality among philosophers of biology and biologists have focused on evolutionary individuality. This includes discussions over units of selection, the replicator/ interactor distinction (Hull 1980), Darwinian individuals (Godfrey-Smith 2009), the possibility of defining species as individuals (Hull 1978;Haber 2016), the question of how groups of entities can aggregate and form new individuals (Buss 1987;Maynard Smith and Szathmáry 1995;Michod 1999), as well as multilevel selection and the constitution of an organism from an evolutionary viewpoint (Okasha 2006;Queller and Strassmann 2009). Other fields also have much to say about the concept of a biological individual, including, for instance, ecology (Huneman 2014). ...
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... In the last four decades or so, especially after the founding work of David Hull, most of the debates about biological individuality among philosophers of biology and biologists have focused on evolutionary individuality. This includes discussions over units of selection, the replicator/ interactor distinction (Hull 1980), Darwinian individuals (Godfrey-Smith 2009), the possibility of defining species as individuals (Hull 1978;Haber 2016), the question of how groups of entities can aggregate and form new individuals (Buss 1987;Maynard Smith and Szathmáry 1995;Michod 1999), as well as multilevel selection and the constitution of an organism from an evolutionary viewpoint (Okasha 2006;Queller and Strassmann 2009). Other fields also have much to say about the concept of a biological individual, including, for instance, ecology (Huneman 2014). ...
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... There are two distinct issues at play in making inferences about the existence of ecological kinds. Are ecological systems compositionally formed in ways that allow them to be ongoing spatiotemporally bound individuals (Hull 1976;Haber 2016)? If so, they can be individuals. ...
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... Although this form of character (or, more appropriately, topological) congruence could also potentially be couched in an individualist paradigm as a form of 'recurrence of concordance' [sensu Haber (2016), see that work for further discussion, cf. 'consilience of inductions' (Ruse, 1987)], it is likely that natural kinds qua similarity classes will remain of greater pragmatic (i.e. ...
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