Marc Ereshefsky

A number of authors have argued that the thesis that species are individuals has important implications for macroevolutionary theory. More specifically, some authors claim that the thesis lends support to the Theory of Punctuated Equilibrium and indicates the existence of species selection. In this paper, I argue that the alleged individuality of species is neither necessary nor sufficient for the truth of that theory or for the existence of species selection. I also argue, contrary to the claims of some, that the individuality of a group is not a necessary requirement for a group to be a unit of selection.

Darwin offered an intriguing answer to the species problem. He doubted the existence of the species category as a real category in nature, but he did not doubt the existence of those taxa called ‘‘species’’. And despite his scepticism of the species category, Darwin continued using the word ‘‘species’’. Many have said that Darwin did not understand the nature of species. Yet his answer to the species problem is both theoretically sound and practical. On the theoretical side, DarwinÕs answer is confirmed by contemporary biology, and it offers a more satisfactory answer to the species problem than recent attempts to save the species category. On the practical side, DarwinÕs answer frees us from the search for the correct theoretical definition of ‘‘species’’. But at the same time it does not require that we banish the word ‘‘species’’ from biology as some recent sceptics of the species category advocate. Ó The Willi Hennig Society 2010

We tend to think that there are different types of biological taxa: some taxa are species, others are genera, while others are families. Linnaeus gave us his ranks in 1731. Biological theory has changed since Linnaeus’s time. Nevertheless, the vast majority of biologists still assign Linnaean ranks to taxa, even though that practice is at odds with evolutionary theory and even though it causes a number of practical problems. The Linnaean ranks should be abandoned and alternative methods for displaying the hierarchical relations of taxa should be adopted

Paul Thompson, John Beatty, and Elisabeth Lloyd argue that attempts to resolve certain conceptual issues within evolutionary biology have failed because of a general adherence to the received view of scientific theories. They maintain that such issues can be clarified and resolved when one adopts a semantic approach to theories. In this paper, I argue that such conceptual issues are just as problematic on a semantic approach. Such issues arise from the complexity involved in providing formal accounts of theoretical laws and scientific explanations. That complexity is due to empirical and pragmatic considerations, not one's adherence to a particular formal approach to theories. This analysis raises a broader question. How can any formal account properly represent the complex nature of empirical phenomena?

The vast majority of biological taxonomists use the Linnaean system when constructing classifications. Taxa are assigned Linnaean ranks and taxon names are devised according to the Linnaean rules of nomenclature. Unfortunately, the Linnaean system has become theoretically outdated. Moreover, its continued use causes a number of practical problems. This paper begins by sketching the ontological and practical problems facing the Linnaean system. Those problems are sufficiently pressing that alternative systems of classification should be investigated. A number of proposals for an alternative system are introduced and evaluated. The best aspects of those proposals are brought together to form a post-Linnaean system, and a comparison of the Linnaean and post-Linnaean systems is conducted. The final section of this paper considers not only the theoretical reasons for replacing the Linnaean system, but also the practical feasibility of adopting an alternative system.

Many writers claim that human kinds are significantly different from biological and natural kinds. Some suggest that humans kinds are unique because social structures are essential for the etiology of human kinds. Others argue that human cultural evolution is decidedly different from other forms of evolution. In this paper I suggest that the gulf between humans and our biological relatives is not as wide as some argue. There is a taxonomic difference between human and nonhuman organisms, but such factors as social structure and cultural evolution do not distinguish us from many other organisms.

The received view in the philosophy of biology is that biological taxa (species and higher taxa) do not have essences. Recently, some philosophers (Boyd, Devitt, Griffiths, LaPorte, Okasha, and Wilson) have suggested new forms of biological essentialism. They argue that according to these new forms of essentialism, biological taxa do have essences. This article critically evaluates the new biological essentialism. This article’s thesis is that the costs of adopting the new biological essentialism are many, yet the benefits are none, so there is no compelling reason to resurrect essentialism concerning biological taxa.

This paper clarifies the historical nature of species by showing that species are path-dependent entities. A species’ identity is not determined by its intrinsic properties or its origin, but by its unique evolutionary path. Seeing that species are path-dependent entities has three implications: it shows that origin essentialism is mistaken, it rebuts two challenges to the species-are-historical-entities thesis, and it demonstrates that the identity of a species during speciation depends on future events

We tend to think that there are different types of biological taxa: some taxa are species, others are genera, while others are families. Linnaeus gave us his ranks in 1731. Biological theory has changed since Linnaeus's time. Nevertheless, the vast majority of biologists still assign Linnaean ranks to taxa, even though that practice is at odds with evolutionary theory and even though it causes a number of practical problems. The Linnaean ranks should be abandoned and alternative methods for displaying the hierarchical relations of taxa should be adopted.