According to a doctrine that has been popularized by Kripke and Putnam, a natural kind term like 'bird' rigidly designates the kind with the microstructure of sample birds. This microstructure is the essence of birdhood, so our learning what the relevant microstructure is our discovery of the kind's essence. We have discovered that some statement like 'The bird is the taxon with such and such DNA structure' is true. Further, it is commonly added, the discovered microstructure is essential to each (...) particular bird. ;I argue that this general picture is mistaken. I do accept and defend the view that terms like 'bird' are rigid designators. However, the picture at issue has other difficulties. Individual birds are not essentially birds. And the view that biologists have discovered or will discover that the bird kind is identical to some DNA structure or other type of structure seems wrong. We don't discover just what particular characteristic a kind is to be identified with. Rather, the meaning of natural kind terms changes; as science advances, more sophisticated concepts attending kind terms replace older ones. So the Kripke-Putnam account of our discovering the truth of theoretical identity statements seems wrong. ;Fortunately, the account retains some interest despite its falsity, because of its association with the claim that statements like 'The bird is the taxon with such and such DNA structure' are necessary but a posteriori. The above sentence does not express a truth, much less a necessary truth, but the idea that it could have expressed the sort of necessary a posteriori truth it is supposed to express is epistemologically interesting. The very possibility of such necessary a posteriori knowledge deserves some account. I offer an account, arguing that this sort of knowledge is no more impressive from an epistemological standpoint than is knowledge of analytic necessity: indeed, I argue, it is best understood as knowledge of a species of analytic necessity. Independently of this claim, I argue in a concluding discussion that analyticity ought to be accepted by proponents of the necessary theoretical identity statements in question. (shrink)

In this paper, I address the charge that the category species should be abandoned in biological work. The widespread appeal to species in scientific discourse provides a presumption in favor of the category’s usefulness, but a defeasible presumption. Widely acknowledged troubles attend species: these troubles might render the concept unusable by showing that ‘species’ is equivocal or meaningless or in some similar way fatally flawed. Further, there might be better alternatives to species. I argue that the presumption in favor of (...) species is not defeated on these scores. Troubles attending species, which arise on account of contextual variation attending the use of ‘species’, do not indicate that the concept is unusable. And alternatives to the use of ‘species’, which have been proposed in connection with rank-free systematics and in connection with conservation efforts, fail to provide a proper replacement for species. (shrink)

At least three different issues are commonly referred to by the term “the species problem”: one concerns the necessary properties of species, a second the processes responsible for the existence of species, and a third methods for inferring species limits. Solutions have recently been proposed to the first two problems, which are conceptual in nature (the third is methodological). The first equates species with metapopulation lineages and proposes that existence as a separately evolving metapopulation lineage be considered the only necessary (...) property of species. The second views the species category as a cluster concept and proposes that no single process or set of processes be considered necessary for the existence of species. Although these two solutions have been portrayed as being in conflict, they are, in fact, highly compatible. Moreover, the proposals in question clarify the problem concerning methods for inferring the limits of species, which has for a long time been confused with the problem concerning the necessary properties of species. Together these proposals provide the opportunity for biology to move beyond debates about the definition of the species category and focus on estimating the boundaries and numbers of species as well as studying the diverse processes involved in their origin and persistence. BioEssays 27:1263–1269, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Vivoscape, from Latin ‘vivo’ and the English ‘scape’ is presented as a new ecosemiotic agency that integrates the interactions between biological and ecological components of a taxon with the environment. According to this model, the interactions between species and the environment are fused into a new functional unity driven by external and internal events. Sensorial and relational channels are used by a taxon to sense external energy gradients, matter, information and to return actions and proactions in an external operational environment. (...) The eco-field model is suggested as the functional ecosemiotic mechanism associated with each vivoevent. (shrink)