The purpose of this paper is to test the contemporary concept of biological species against some of the problems caused by treating species as spatiotemporally extended entities governed by criteria of persistence, identity, etc. After outlining the general problem of symmetric division in natural objects, I set out some useful distinctions (section 1) and confirm that species are not natural kinds (section 2). Section 3 takes up the separate issue of species definition, focusing on the Biological Species Concept (BSC). Sections (...) 4 and 5 examine the matter of species identity over space and time respectively, as determined by the BSC. Both gradualistic and punctuated equilibrium models of speciation are discussed. In section 6 I argue that the BSC fails to determine adequate criteria for dealing with certain kinds of speciation. Section 7 moves speculatively beyond the BSC to a brief examination of alternatives. (shrink)

The nature and functions of classifications are first discussed and the differences between natural and artificial classifications are explicated. It is shown that borderline-case type problems result not from classifications, but from extending them to wider domains. Some methods of solving such problems are considered. The differences between monothetic and polythetic classifications are also taken up. A new treatment of trees as relations and their levels is developed. Certain kinds of hierarchies such as the classificatory, the inclusional, and the structural (...) are then characterized by means of the tree concept. (shrink)

Essentialism--understood as the doctrine that there are natural kinds--can be sustained with respect to the most fundamental physical entities of the world, as I elsewhere argue. In this paper I take up the question of the existence of natural kinds among complex structures built out of these elementary ones. I consider a number of objections to essentialism, in particular Locke's puzzle about the existence of borderline cases. A number of recent attempts to justify biological taxonomy are critically examined. I conclude (...) that theory partially justifies such taxonomies but supports only a weaker form of essentialism. (shrink)

The recognition of species proceeds by two fairly distinct phases: (1) the sorting of individuals into groups or basic taxa (‘discovery’) (2) the checking of those taxa as candidates for species-hood (‘justification’). The target here is a rational reconstruction of phase 1, beginning with a discussion of key terms. The transmission of ‘meaning’ is regarded as bimodal: definition states the intension of the term, and diagnosis provides a disjunction of criteria for recognition of its extension. The two are connected by (...) a spectrum, with purely theoretical definition at one pole and purely ‘operational’ diagnosis at the other, with the more operational elements explained by the more theoretical. The current plethora of species concepts provides a good example. Accepting the Ghiselin–Hull thesis, that a species is an individual, a basic taxon is therefore also an individual with organisms as its parts. In a generalised synchronic individual its parts are conceptually integrated by an integrating principle (IP), which consists of a relation applying within a plan or rule. Fully developed, such an IP ensures the maximisation of the information content of the individual. A diachronic individual is then the set of its component synchronic parts, and its IP is provided by near-identity in an appropriate space-time (not necessarily physical). The integration of parts of an individual is illuminated by Gasking's concept of a proper group (in this case a chain-group), whose members are related by the relation serially fitting together with, the IP completed by an appropriate plan or rule. Gasking also applied the term cluster to a proper group persisting over a substantial period of time, individuated by any member acting as focus. A basic taxon is therefore a cluster of individuals, integrated by the relation significantly taxonomically similar and the rule in character-space-time. The nature of those concepts is discussed and defended. A species will inherit certain of the attributes of the preceding basic taxon (taxa). In at least the synchronic version its parts (individuals) will resemble each other significantly, providing the intuitive applicability of ‘members of’ and ‘instances of’ a species. Also, the notion that a species’ name is given by pure ostension, via a name-bearer (holotype) is empirically incoherent: the name cannot be applied in practice without an appropriate set of diagnostic traits. (shrink)

This paper analyses the traditionally recognized dependence between observation statements and theories. The analysis proceeds by working out the interrelationship between classification systems and theoretical frameworks. Cuvier's and Darwin's theories are used as examples to illustrate this issue. The second part of the paper develops a model designed to give an account of the historical development of this interrelationship. It is argued that the interdependence is not circular and that it is an integral part of scientific research. It is suggested (...) that an interdependence of the type reflected in the model can be helpful in evaluating research programmes in the history of all the sciences. (shrink)

This is an essay about ethics and environmental responsibility. The thesis is that biologic species qua species--not only as collections of individuals or as elements of ecosystems--deserve moral regard. The argument establishes moral considerability on powers and freedoms of relative self-determination and autonomy. It is argued that species are living beings in their own right with their own projects and interests which deserve special regard. The essay draws from the arguments of Plato, Aristotle, Plotinus, Boethius, Avicenna, Maimonides, Leibniz, Spinoza, Kant, (...) and others, concerning the moral value of natural beings, but situates itself in the contemporary dialogue of environmental ethics. Lengthy consideration is given to species concepts defended by evolution theorists, biological systematists, and ecologists. ;The argument claims that natural beings, including species, have moral value because they have projects and interests which make a legitimate, but not universal, claim on the moral agent. Beings make moral claims when they are integral and integrating, individual, and concreative--conditions comparable to those with which we describe the moral status of a person. We may call such beings rational by analogy to the integration and singularity of intellect, and confer upon them analogous moral consideration. They are due regard in proportion to their projects in the same sense that moral subjects are due regard for having the projects of moral subjects. (shrink)