Online research in philosophy

Difficulties with the typological concept of species led biologists to reject the "typological" presupposition of an archetype which is manifest in each member of a species. The resulting concept of species, which is here called the phenotypic species concept, is considered as implying that biological species are not real. Modern population thinking has given rise to the concept of a species as a gene-pool. This modern concept is contrasted here with the phenotypic concept in light of some general criteria for evaluating species concepts and is shown to be more satisfactory. Finally, it is held that to ask if a species is real is to ask whether the species grouping arrived at by applying the principles involved in the species concept corresponds with groups of organisms amongst which important biological relationships exist. It is argued that in this sense species, as defined by the gene-pool concept, are certainly real.

When conceived as an empirical claim, it is natural to wonder how one might test the hypothesis of multiple realization. I consider general issues of testability, show how they apply specifically to the hypothesis of multiple realization, and propose an auxiliary assumption that, I argue, must be conjoined to the hypothesis of multiple realization to ensure its testability. I argue further that Bechtel and Mundale (1999) go astray because they fail to appreciate the need for this auxiliary assumption. †To contact the author, please write to: Department of Philosophy, University of Wisconsin–Madison, 5185 Helen C. White Hall, 600 North Park Street, Madison, WI 53706; e‐mail: lshapiro@wisc.edu.

This essay comments on the theory of social norms developed by Cristina Bicchieri in The Grammar of Society ( 2006 ). It applauds her theory of norms but argues that it cannot account for the experimental results concerning ultimatum games. A theory of fairness is also needed. It develops a number of specific criticisms of her way of incorporating the influence of norms into preferences. †To contact the author, please write to: Department of Philosophy, University of Wisconsin–Madison, 5197 Helen C. White Hall, 600 N. Park Street, Madison, WI 53706‐1474; e‐mail: dhausman@wisc.edu.

Speciation is an aspect of evolutionary biology that has received little philosophical attention apart from articles mainly by biologists such as Mayr (1988). The role of speciation as a terminus a quo for the individuality of species or in the context of punctuated equilibrium theory has been discussed, but not the nature of speciation events themselves. It is the task of this paper to attempt to bring speciation events into some kind of general scheme, based primarily upon the work of Sergey Gavrilets on adaptive landscapes, using migration rate, or gene flow, as the primary scale, and concluding that adaptive and drift explanations are complementary rather than competing. I propose a distinction between intrinsic and extrinsic selection, and the notion of reproductive reach and argue that speciation modes should be discriminated in terms of gene flow, the nature of selection maintaining reproductive reach, and whether the predominant cause is selective or stochastic. I also suggest that the notion of an adaptive “quasispecies” for asexual species is the primitive notion of species, and that members of reproductively coherent sexual species are additionally coadapted to their mating partners.

The simple question, what is empirical success? turns out to have a surprisingly complicated answer. We need to distinguish between meritorious fit and ‘fudged fit', which is akin to the distinction between prediction and accommodation. The final proposal is that empirical success emerges in a theory dependent way from the agreement of independent measurements of theoretically postulated quantities. Implications for realism and Bayesianism are discussed. ‡This paper was written when I was a visiting fellow at the Center for Philosophy of Science at the University of Pittsburgh; I thank everyone for their support. †To contact the author, please write to: Department of Philosophy, University of Wisconsin–Madison, 5185 Helen C. White Hall, 600 North Park Street, Madison, WI 53706; e-mail: mforster@wisc.edu.

Over the last 2,300 years or so, many philosophers have believed that species are individuated by essences that are at least in part intrinsic. Psychologists tell us most folks also believe this view. But most philosophers of biology have abandoned the view, in light of evolutionary conceptions of species. In defiance, Michael Devitt has attempted in this journal to resurrect a version of the view, which he calls Intrinsic Biological Essentialism. I show that his arguments for the resurrection fail, and I identify challenges that face anyone wishing to defend Intrinsic Biological Essentialism. *Received February 2009; revised September 2009. †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: mjbarker2@wisc.edu.

We defend a realistic attitude towards biological species. We argue that two species are not different species because they differ in intrinsic features, be they phenotypic or genomic, but because they are separated with regard to gene flow. There are no intrinsic species essences. However, there are relational ones. We argue that bearing a gene flow relation to conspecifics may serve as the essence of a species. Our view of the species as a Gene-Flow Community differs from Mayr’s definition of the species as a reproductive community. In a reproductive community, each organism is able to successfully reproduce with each other. However, there are species in which geographically distant organisms lost their ability to successfully reproduce, due to strong genetic adaptations to the respective local environmental conditions. Despite this loss of the ability to mutually reproduce, they are still bound by gene flow via continuous intermediate populations. This replacement of Mayr’s notion of an interbreeding potential as a criterion for species membership has important implications for the treatment of populations in allopatry and sympatry.

Over the decades, there has been substantial empirical evidence showing that the unity of species cannot be maintained by gene flow. The biological species concept is inconclusive on this point. The suggestion is made that the unity of species is maintained rather by selection constantly spreading new alleles throughout the species, or bygene circulation. There is a lack in conceptual distinction between gene flow and gene circulation which lies at the heart of the problem. The concept of gene circulation also sheds some new light on the problem of typology and on such a broad concept as evolution. A new species definition is proposed.

A far-reaching and influential view in evolutionary biology claims that species are cohesive units held together by gene flow. Biologists have recognized empirical problems facing this view; after sharpening the expression of the view, we present novel conceptual problems for it. At the heart of these problems is a distinction between two importantly different concepts of cohesion, what we call integrative and response cohesion. Acknowledging the distinction problematizes both the explanandum of species cohesion and the explanans of gene flow that are central to the view we discuss. We conclude by tracing four broader implications for the study and conceptualization of species.