I argue for accepting a pluralist approach to species, while rejecting the realism about species espoused by P. Kitcher and a number of other philosophers of biology. I develop an alternative view of species concepts as divisions of organisms into groups for study which are relative to the systematic explanatory interests of biologists at a particular time. I also show how this conception resolves a number of difficult puzzles which plague the application of particular species concepts.

A long-standing debate has dominated systematic biology and the ontological commitments made by its theories. The debate has contrasted individuals and the part – whole relationship with classes and the membership relation. This essay proposes to conceptualize the hierarchy of higher taxa is terms of a hierarchy of homeostatic property cluster natural kinds (biological species remain largely excluded from the present discussion). The reference of natural kind terms that apply to supraspecific taxa is initially fixed descriptively; the extension of those (...) natural kind terms is subsequently established by empirical investigation. In that sense, classification precedes generalization, and description provides guidance to empirical investigation. The reconstruction of a hierarchy of (homeostatic property cluster) natural kinds is discussed in the light of cladistic methods of phylogeny reconstruction. (shrink)

I have recently argued that origin essentialism regarding individual organisms entails that natural selection does not explain why individual organisms have the traits that they do. This paper defends this and related theses against Mohan Matthen's recent objections.

The so-called ‘‘species problem’’ has plagued evolution- ary biology since before Darwin’s publication of the aptly titled Origin of Species. Many biologists think the problem is just a matter of semantics; others complain that it will not be solved until we have more empirical data. Yet, we don’t seem to be able to escape discussing it and teaching seminars about it. In this paper, I briefly examine the main themes of the biological and philosophical liter- atures on the species problem, (...) focusing on identifying common threads as well as relevant differences. I then argue two fundamental points. First, the species problem is not primarily an empirical one, but it is rather fraught with philosophical questions that require—but cannot be settled by—empirical evidence. Second, the (dis-)solution lies in explicitly adopting Wittgenstein’s idea of ‘‘family resemblance’’ or cluster concepts, and to consider spe- cies as an example of such concepts. This solution has several attractive features, including bringing together apparently diverging themes of discussion among bio- logists and philosophers. The current proposal is con- ceptually independent (though not incompatible) with the pluralist approach to the species problem advocated by Mishler, Donoghue, Kitcher and Dupre ́, which implies that distinct aspects of the species question need to be emphasized depending on the goals of the researcher. From the biological literature, the concept of species that most closely matches the philosophical discussion pre- sented here is Templeton’s cohesion idea. (shrink)

Treating species as individuals and not classes has been crucial to the integration of evolutionary theory with modern systematics. Despite the theoretically important role the concept of individuality plays in modern phylogenetic systematics and in evolutionary theory more generally, many have been content to rely on common-sense intuitions about what counts as an individual. One of the most often cited intuitions is that individuals should be defined intrinsically. Unfortunately, common-sense intuitions like this one have proven to be inadequate for identifying (...) and characterizing historical individuals (like species). An examination of real-world biological examples shows that our common-sense intuitions are equally inadequate when applied to at least some biological organisms--the paradigm individuals. (shrink)

In her "Species Are Individuals" (1985), Mary Williams offers informal arguments and a sketched proof which allegedly show that species are individuals with respect to evolutionary theory. In this paper, I suggest that her informal arguments are insufficient for showing that clans are not sets and that species are individuals. I also argue that her sketched proof depends on three questionable assumptions.

The so-called ‘type method’ widely employed in biological taxonomy is often seen as conforming to the causal-historical theory of reference. In this paper, I argue for an alternative account of reference for biological nomenclature in which taxon names are understood as descriptive names. A descriptive name, as the concept came to be known from the work of Gareth Evans, is a referring expression introduced by a definite description. There are three main differences between the DN and the causal account. First, (...) according to the DN account, rather than fixing a name to a referent, the assignment of a type specimen to serve as the name-bearer for a taxon should be seen as performatively establishing a synonymy between a name and a definite description of the form “the taxon whose type is t”. Each taxon name is therefore associated with a criterion of application, a semantic rule that establishes the connection between the name and the descriptive content. This is the second major difference from the causal account: taxon names do have some descriptive content associated with them. The final locus of dissent concerns the strength of the modality resulting from the usage of taxon names. In order to address this point, I use the DN account to focus on the debate between Matt Haber and Joeri Witteveen concerning misidentification of type specimens, misapplication of names, and the truth conditions of Joseph LaPorte’s de dicto necessary sentence “Necessarily, any species with a type specimen contains its type specimen”. Using a pragmatic variant of the distinction between attributive and referential uses of descriptions, I argue that a metalinguistic version of the de dicto sentence is in fact falsified, as previously argued by Haber. (shrink)

Science is about conceptualizing the natural world in a way that can be understood by human beings while at the same time reflecting as much as possible what we can empirically infer about how the world actually is. Among the crucial tools that allow scientists to formulate hypotheses and to contribute to a progressive understanding of nature are the use of imagery and metaphors, on the one hand, and the ability to assume certain starting points on which to build new (...) avenues of inquiry on the other hand. The premise of this work is that, in the words of philosopher of science Daniel Dennett, "There is no such thing as philosophy-free science; there is only science whose philosophical baggage is taken on board without examination." The purpose here is precisely to examine some of this philosophical baggage, and to see where such analysis may lead us. Obviously, it is not possible for a single project to take on science as a whole, or even an entire discipline such as physics, or ecology. Therefore, the core of this work is constituted by a series of eight case studies drawn from the field of evolutionary biology, with which I am particularly familiar as a practicing biologist. The hope is that combining expertise in both philosophy and science in one person, the resulting insights might be useful for the practicing scientist as well as because of their value as philosophical inquires. The dissertation is a combination of conceptual analysis and science criticism applied to specific questions in organismal biology, largely of an evolutionary nature, with the eight case studies grouped into three broad categories: Unexamined Baggage, Bad Habits, and Good and bad metaphors. (shrink)

For the past twenty years, taxonomy has been in a state of turmoil. This confusion brings along with it four distinct schools of thought, each of which offers a different concept of biological species. The thesis will show that these concepts are purely operational and have only a weak theoretical force. In turn, it will be argued that a sound definition of species uses the notion of natural kinds, which is itself defined in term of non-causal nomological regularities.