We suggest that human culture exhibits key Darwinian evolutionary properties, and argue that the structure of a science of cultural evolution should share fundamental features with the structure of the science of biological evolution. This latter claim is tested by outlining the methods and approaches employed by the principal subdisciplines of evolutionary biology and assessing whether there is an existing or potential corresponding approach to the study of cultural evolution. Existing approaches within anthropology and archaeology demonstrate a good match with (...) the macroevolutionary methods of systematics, paleobiology, and biogeography, whereas mathematical models derived from population genetics have been successfully developed to study cultural microevolution. Much potential exists for experimental simulations and field studies of cultural microevolution, where there are opportunities to borrow further methods and hypotheses from biology. Potential also exists for the cultural equivalent of molecular genetics in “social cognitive neuroscience,” although many fundamental issues have yet to be resolved. It is argued that studying culture within a unifying evolutionary framework has the potential to integrate a number of separate disciplines within the social sciences. (shrink)

I analyze a number of widespread misconceptions concerning species. The species category, defined by a concept, denotes the rank of a species taxon in the Linnaean hierarchy. Biological species are reproducing isolated from each other, which protects the integrity of their genotypes. Degree of morphological difference is not an appropriate species definition. Unequal rates of evolution of different characters and lack of information on the mating potential of isolated populations are the major difficulties in the demarcation of species taxa.

Four ordering systems have been used most frequently in taxonomy: (1) special purpose classifications, (2) downward classifications (identification schemes), (3) upward or grouping classifications (traditional), and (4) Hennigian phylogenetic systems. The special properties of these four systems are critically evaluated. Grouping classifications and phylogenetic systems have very different objectives: the former the documentation of similarity and closeness of relationship, the latter of phylogeny. Both are legitimate ordering systems.

Phylogenetic systematics is one of the most important analytical frameworks of modern Biology. It seems to be common knowledge that within phylogenetics, ‘groups’ must be defined based solely on the synapomorphies or on the “derived” characters that unite two or more taxa in a clade or monophyletic group. Thus, the idea of synapomorphy seems to be of fundamental influence and importance. Here I will show that the most common and straightforward understanding of synapomorphy as a shared derived character is not (...) sufficient and eventually must be rejected in favor of Nelson’s relational interpretation of such term. Arguing for this point and using three examples from previously published Apes’ genomic matrices, I explicitly demonstrate that the relationship )) with Hylobatidae as a sister taxon, may be successfully recovered by three-taxon statement analysis and three-taxon statement average consensus analysis even if all of the evident standard shared derived molecular characters of the relationship )) with Hylobatidae as a sister taxon, have been excluded from the molecular alignments. Neither conventional Maximum Parsimony nor Maximum Likelihood or Bayesian Inference can do this in such situation. Thus, our results show that the relationship )) with Hylobatidae as a sister taxon has appeared, in some way, behind standard shared derived characters: the last ones could be excluded, but the relationship remains the same. (shrink)

We report evidence further supporting homology between proteins in the F1FO‐ATP synthetase and the bacterial flagellar motor (BFM). BFM proteins FliH, FliI, and FliJ have been hypothesized to be homologous to FO‐b + F1‐δ, F1‐α/β, and F1‐γ, with similar structure and interactions. We conduct a further test by constructing a gene order dataset, examining the order offliH,fliI, andfliJgenes across the phylogenetic breadth of flagellar and nonflagellar type 3 secretion systems, and comparing this to published surveys of gene order in the (...) F1FO‐ATP synthetase, its N‐ATPase relatives, and the bacterial/archaeal V‐ and A‐type ATPases. Strikingly, thefliHIJgene order was deeply conserved, with the few exceptions appearing derived, and exactly matching the widely conserved F‐ATPase gene orderatpFHAG, coding for subunits b‐δ‐α‐γ. The V/A‐type ATPases have a similar conserved gene order. Our results confirm homology between these systems, and suggest a rare case of synteny conserved over billions of years, predating the Last Universal Common Ancestor (LUCA). (shrink)

Species are considered the basic unit of biological classification and evolution. Hence, they are used as a benchmark in several fields, although the ontological status of such a category has always been a matter of debate. This paper aims to discuss the problem of the definition of species within the new mechanistic approach. Nevertheless, the boundary between entities, activities, and mechanisms remains difficult to establish and always requires an analysis of what is meant by explanation. As a case study, the (...) paper describes the debate concerning the species category by considering different kingdoms: Animals, Bacteria, and Fungi. The inherently biological differences between those groups prevent the use of a single, universally applicable concept of species that could fit the mechanisms responsible for the variability present in these kingdoms. The same issue is encountered within each group, as highlighted through a focus on mammals and microbes. This controversy has given rise to opposite approaches, namely: monism, which looks for a single definition that might account for all species, and pluralism, which admits that different groups of organisms require somewhat different definitions. In order to develop an adequate definition of species, we propose to apply a new mechanistic framework, which considers the ontic-epistemic dimensions of scientific explanation in close parallel. The apt correlation between epistemic and the ontic aspects highlights the way in which the concept of species and the reference to data are strictly co-determined. This suggests that the concept of species is better understandable within a dual ontic-epistemic approach. (shrink)

Traditionally, phylogenetic relations among living and extinct species have been estimated from their morphology, particularly that of the bones and teeth. During the past two decades, molecular comparisons of DNA, RNA and proteins have increasingly influenced the taxonomy of living forms. Recently, radio‐immunoassay (RIA) has been applied to the resolution of phylogenetic disputes by testing the relationships of residual fossil proteins with those of living organisms.

We examine three critical aspects of Popper’s formulation of the ‘ Logic of Scientific Discovery ’—evidence, content and degree of corroboration—and place these concepts in the context of the Tree of Life (ToL) problem with particular reference to molecular systematics. Content, in the sense discussed by Popper, refers to the breadth and scope of existence that a hypothesis purports to explain. Content, in conjunction with the amount of available and relevant evidence, determines the testability, or potential degree of corroboration, of (...) a statement; content distinguishes scientific hypotheses from metaphysical assertions. Degree of corroboration refers to the relative and tentative confidence assigned to one hypothesis over another, based upon the performance of each under critical tests. Here we suggest that systematists attempt to maximize content and evidence to increase the potential degree of corroboration in all phylogenetic endeavors. Discussion of this “total evidence” approach leads to several interesting conclusions about generating ToL hypotheses. (shrink)

It is often said that there is just one “objective” tree of life: a single accurate branching hierarchy of species reflecting order of descent. For any two species there is a single correct answer as to whether one is a “daughter” of the other, whether the two are “sister species” by virtue of their descent from a common parental species, whether they belong to a family line that excludes any given third species, and so on. This position is not right. (...) We may whittle a tree of life, paring troublesome branches, in order to portray an ordering that admits of no legitimate dissent. But the history of life can sustain many legitimate arrangements of the same branches of species. The same can be said about other taxonomically relevant groups besides species, such as “Least Inclusive Taxonomic Units” (LITUs), so the basic claim survives even if we abandon traditional species. Similarly, the claim survives even if we distinguish between synchronic and diachronic groups, even if we consider polytomies, even if we distinguish between models and the world modeled, and even if we recognize an objective world. Nor is the claim merely an epistemic one. (shrink)

In this paper I take issue with the doctrine that organisms belong of their very essence to the natural kinds (or biological taxa, if these are not kinds) to which they belong. This view holds that any human essentially belongs to the species Homo sapiens, any feline essentially belongs to the cat family, and so on. I survey the various competing views in biological systematics. These offer different explanations for what it is that makes a member of one species, family, (...) etc. a member of that taxon. Unfortunately, none of them offers an explanation that is compatible with the essentialism in question. (shrink)

Deduction leads to causal explanation in phylogenetic inference when the evidence, the systematic character, is conceptualized as a transformation series. Also, the deductive entailment of modus tollens is satisfied when those kinds of events are operationalized as patristic difference. Arguments to the contrary are based largely on the premise that character-states are defined intensionally as objects, in terms of similarity relations. However, such relations leave biologists without epistemological access to the causal explanation and explanatory power of historical statements. Moreover, the (...) prediction-making to which those kinds of relations are limited in practice can lead to a category error—the mental conversion of an abstraction into a thing . The latter practices and problems characterize pattern cladistics, taxa being interpreted as homeostatic property cluster natural kinds, and other instrumentalist research programs. (shrink)

Homology is among the most important comparative concepts in biology. Today, the evolutionary reinterpretation of homology is usually conceived of as the most important event in the development of the concept. This paradigmatic turning point, however important for the historical explanation of life, is not of crucial importance for the development of the concept of homology itself. In the broadest sense, homology can be understood as sameness in reference to the universal guarantor so that in this sense the different concepts (...) of homology show a certain kind of “metahomology”. This holds in the old morphological conception, as well as in the evolutionary usage of homology. Depending on what is (or was) taken as a guarantor, different types of homology may be distinguished (as idealistic, historical, developmental etc.). This study represents a historical overview of the development of the homology concept followed by some clues on how to navigate the pluralistic terminology of modern approaches to homology. (shrink)

Mimicry is often cited as a compelling demonstration of the power of natural selection. By adopting signs of a protected model, mimics usually gain a reproductive advantage by minimising the likelihood of being preyed upon. Yet while natural selection plays a role in the evolution of mimicry, it can be doubted whether it fully explains it. Mimicry is mediated by the emergence of formally analogous patterns between unrelated organisms and by the fact that these patterns are meaningfully perceived as similar. (...) The perception of similarity is always perceiver-dependent. Similarities between for instance colours are psychophysical phenomena, and their existence is conditioned by an intimate interdependence between perceivers and perceptible reality. In this sense, mimicry is by its very nature dualistic. The analogy in form needed to establish a mimicry does not emerge out of the blue. It depends on the ecological context and the morphogenetic potential of a species. In our proposal, we take into account both the developmental generators of formally analogous structures and the perceptual and cognitive processes that lead to the emergence of mimicry. We show that some of the rather controversial and nowadays largely neglected ideas found in non-Anglo-Saxon literature on mimicry deserve closer attention. We suggest that the diversity of mimicry types is due to differences in variational properties of form-generating and perceptual systems among diverse groups of organisms. We also anticipate that processes studied within social psychology and emotion research probably take place, at least in a simplified form, also in non-human animals. Finally, we argue that these meaning-attributive processes underlie the functionality of mimicry. (shrink)

I defend a view of the species category, pluralistic realism, which is designed to do justice to the insights of many different groups of systematists. After arguing that species are sets and not individuals, I proceed to outline briefly some defects of the biological species concept. I draw the general moral that similar shortcomings arise for other popular views of the nature of species. These shortcomings arise because the legitimate interests of biology are diverse, and these diverse interests are reflected (...) in different legitimate approaches to the classification of organisms. In the final section, I show briefly how the pluralistic approach can help to illuminate some areas of biological and philosophical dispute. (shrink)

This paper discusses a philosophical issue in taxonomy. At least one philosopher has suggested thc taxonomic principle that scientific kinds are disjoint. An opposing position is dcfcndcd here by marshalling examples of nondisjoint categories which belong to different, cocxisting classification schcmcs. This dcnial of thc disjoinmcss principle can bc recast as thc claim that scientific classification is "int<-:rcst—rclativc". But why would anyone have held that scientific categories arc disjoint in the first place'? It is argued that this assumption is nccdcd (...) in one attempt t0 dcrivc csscntialism. This shows why the csscntialist and intc-:rcst—r<-zlativc approaches to classification arc in conflict. (shrink)

Weak links, in the form of inadequacies in both reasoning and supporting evidence, exist at several critical steps in the derivation of an hierarchical concept of evolution from punctuated equilibria. Punctuation itself is predicated on a distorted reading of phyletic change as phyletic gradualism, and of allopatric speciation as the instantaneous formation of unchanging typological taxa. The concept of punctuation is further confounded by the indescriminate employment of the same term to denote both a causal explanation for evolutionary change and (...) an outcome of substantiated evolutionary processes. Even when the intended usage for the term is specified, each denotation of punctuation entails respective drawbacks. As a causal explanation, punctuation clearly belongs to the class of quantum theories with all their attendant impedimenta, including special salsatory non-adaptive mechanisms of evolutionary change. Redefinition of punctuation as a pattern of morphologic change reduces it to one possible outcome of known microevolutioanry processes, thus obviating any need for an hierarchical explanation of macroevolution. While vacillation between usages has preserved the term in the literature, the end result of this obfuscation has been a circle of faulty reasoning in which the pattern of punctuation is invoked as its own proof. Widespread confusion concerning what constitutes an adequate test of punctuation is directly attributable to imprecision in both the original and revised formulations of the concept.The argument for species-level selection is based on the typological and philosphically flawed premise of species as individuals, and further requires the hypothesis of heritable emergent properties, for which empirical evidence is lacking. (shrink)

Although molecular systematists may use the terminology of cladism, claiming that the reconstruction of phylogenetic relationships is based on shared derived states , the latter is not the case. Rather, molecular systematics is based on the assumption, first clearly articulated by Zuckerkandl and Pauling , that degree of overall similarity reflects degree of relatedness. This assumption derives from interpreting molecular similarity between taxa in the context of a Darwinian model of continual and gradual change. Review of the history of molecular (...) systematics and its claims in the context of molecular biology reveals that there is no basis for the “molecular assumption.”. (shrink)

Karl Popper has been one of the few philosophers of sciences who has influenced scientists. I evaluate Popper's influence on our understanding of evolutionary theory from his earliest publications to the present. Popper concluded that three sorts of statements in evolutionary biology are not genuine laws of nature. I take him to be right on this score. Popper's later distinction between evolutionary theory as a metaphysical research program and as a scientific theory led more than one scientist to misunderstand his (...) position on evolutionary theory as a scientific theory. In his later work Popper also introduced what he took to be improvements of evolutionary theory. Thus far these improvements have had almost no influence on evolutionary biology. I conclude by examining the influence of Popper on the reception of cladistic analysis. (shrink)

In recent years two groups of taxonomists have attempted to influence the general goals and methods of biological classification. The first group, which emerged in the late 1950’s, has been called variously neo-Adansonian, numerical, computer and phenetic taxonomy. The founders of this school, Robert R. Sokal and P.H.A. Sneath, termed their unified approach to systematics “neo-Adansonian” because of the affinities which they saw between their views and those of the 18th century botanist, Michel Adanson (1727-1806). Today little mention is made (...) of Adanson. His ideas turned out not to be as prescient as Sokal and Sneath had at first thought. Besides, he had served his purpose as a patron saint ([79], p. 23). Sokal and Sneath also termed their approach “numerical” because they believed that taxonomists should make greater use of available mathematical techniques. Not only should taxonomic characters be coded quantitatively but also estimates of affinity should be made on the basis of explicitly stated clustering procedures. (shrink)

Biological species have been treated traditionally as spatiotemporally unrestricted classes. If they are to perform the function which they do in the evolutionary process, they must be spatiotemporally localized individuals, historical entities. Reinterpreting biological species as historical entities solves several important anomalies in biology, in philosophy of biology, and within philosophy itself. It also has important implications for any attempt to present an "evolutionary" analysis of science and for sciences such as anthropology which are devoted to the study of single (...) species. (shrink)

Although naming biological clades is a major activity in taxonomy, little attention has been paid to what these names actually refer to. In philosophy, definite descriptions have long been considered equivalent to the meaning of names and biological taxonomy is a scientific application of these ideas. One problem with definite descriptions as the meanings of names is that the name will refer to whatever fits the description rather than the intended individual (clade). Recent proposals for explicit phylogenetic definitions of clade (...) names suffer from similar problems and we argue that clade names cannot be defined since they lack intension. Furthermore we stress the importance of tree-thinking for phylogenetic reference to work properly. (shrink)

Since Darwin's theory of evolution by natural selection, the idea of descent with modification came to dominate systematics, and so the study of morphology became subgugated to the reconstruction of phylogenies. Reinstating the organism in the theory of evolution (Ho & Saunders, 1979; Webster & Goodwin, 1982) leads to a project inrational taxonomy (Ho, 1986, 1988a), which attempts to classify biological forms on the basis of transformations on a given dynamical structure.Does rational taxonomy correspond to thenatural system that Linnaeus and (...) his contemporaries as well as all pre-Darwinian morphologists had in mind? Here, we examine how rational taxonomy and the natural system can coincide in the dynamics of processes generating forms during development, which conferexclusivity, genericity androbustness to the forms that do exist. We use the example of segmentation, especially inDrosophila, as an illustration to explore the implications of rational taxonomy for evolution and systematics, and the relationship between ontogeny and phylogeny. (shrink)

Species serve as both the basic units of macroevolutionary studies and as the basic units of taxonomic classification. In this paper I argue that the taxa identified as species by the Phylogenetic Species Concept (Mishler and Brandon 1987) are the units of biological organization most causally relevant to the evolutionary process but that such units exist at multiple levels within the hierarchy of any phylogenetic lineage. The PSC gives us no way of identifying one of these levels as the privileged (...) level on which taxonomic classifications can be based. (shrink)

The relation between method, concept and theory in science is complicated. I seek to shed light on that relation by considering an instance of it in systematics: The additional challenges phylogeneticists face when reconstructing phylogeny not at a single level, but simultaneously at multiple levels of the hierarchy. How does this complicate the task of phylogenetic inference, and how might it inform and shape the conceptual foundations of phylogenetics? This offers a lens through which the interplay of method, theory and (...) concepts may be understood in systematics, which, in turn, provides data for a more general account. (shrink)

I spell out and update the individuality thesis, that species are individuals, and not classes, sets, or kinds. I offer three complementary presentations of this thesis. First, as a way of resolving an inconsistent triad about natural kinds; second, as a phylogenetic systematics theoretical perspective; and, finally, as a novel recursive account of an evolved character. These approaches do different sorts of work, serving different interests. Presenting them together produces a taxonomy of the debates over the thesis, and isolates ways (...) it has been productive. This goes to the larger point of this paper: a defense of the individuality thesis in terms of its utility, and an update of it in light of recent theoretical developments and empirical work in biology. (shrink)

Samir Okasha argues that clade selection is an incoherent concept, because the relation that constitutes clades is such that it renders parent-offspring (reproduction) relations between clades impossible. He reasons that since clades cannot reproduce, it is not coherent to speak of natural selection operating at the clade level. We argue, however, that when species-level lineages and clade-level lineages are treated consistently according to standard cladist commitments, clade reproduction is indeed possible and clade selection is coherent if certain conditions obtain. Despite (...) clade selection's logical coherence, however, we share some of Okasha's pessimism. Whether or not clades are a unit of selection is ultimately a question of empirical support and theoretical import. (shrink)

I adopt a cladistic view of species, and explore the possibility that there exists an equally valuable cladistic view of organismic traits. This suggestion seems to run counter to the stress on functional views of biological traits in recent work in philosophy and psychology. I show how the tension between these two views can be defused with a multilevel view of biological explanation. Despite the attractions of this compromise, I conclude that we must reject it, and adopt an essentially cladistic (...) conception of biological traits. (shrink)

Problems raised by complex life cycles for standard summaries of evolutionary processes, and for concepts of individuality in biology, are described. I then outline a framework that can be used to compare life cycles. This framework treats reproduction as a combination of production and recurrence and organizes life cycles according to the distribution of steps in which multiplication, bottlenecks, and sex occur. I also discuss fitness and its measurement in complex life cycles and consider some phenomena that raise complications and (...) difficulties for my framework. (shrink)

Die von der Beobachtung des menschlichen Auges unabhängigen genetischen Relationen zwischen den Individuen sind für die Begründung des Artbegriffs das Wesentliche. Die Tatsache, dass die Systematiker in der Praxis meist rein morphologisch arbeiten und nur in wenigen Ausnahmefällen das Verhalten der Individuen einander gegenüber direkt studieren, ändert daran durchaus nichts.Es gibt zwei grundverschiedene Weisen die Individuen und deren genetische Relationen zu betrachten. Entweder man schaut “horizontal”, d.h. innerhalb einer kurzen Zeitspanne, oder man übersieht das Ganze “vertikal”, d.h. ohne zeitliche Begrenzung.Anhand (...) einer Kombination von Abstammungslehre und Ergebnissen der Genetik wirde in Modell formiert, an dem die mögliche Modell-Objektivität von bestimmten Gruppierungen von Individuen zu Arten abgemessen wird.Bei der horizontalen Betrachtungsweise gibt es modell-objektive Arten nach der DefinitionMayr's : “Species are groups of actually or potentially interbreeding natural populations, which are isolated from other such groups”. Gruppe A ist so innerhalb der arbiträr begrenzten Periode p eine modell-objektive Art in der Relation zu Gruppe B.Vertikal sind keine modell-objektiven Gruppierungen von Individuen möglich. So müssen Arten einander gegenüber arbiträr abgegrenzt werden.Eine horizontale Art kann manchmal arbiträr in trinominal benannte Unterarten aufgeteilt werden, auf Grund von geographisch lokalisierten morphologischen Merkmalen. Eine analoge trinominale Benennung von stratigraphischen Rassen oder vertikalen Unterarten, nach zeitlich lokalisierten Merkmalen, ist sehr verwirrend. Es gibt keinen einzigen zwingenden Grund vertikal neben Arten, als eine spezielle Kategorie, auch noch Unterarten zu konstruieren. (shrink)

A naturalistic account of the strengths and limitations of cladistic practice is offered. The success of cladistics is claimed to be largely rooted in the parsimony-implementing congruence test. Cladists may use the congruence test to iteratively refine assessments of homology, and thereby increase the odds of reliable phylogenetic inference under parsimony. This explanation challenges alternative views which tend to ignore the effects of parsimony on the process of character individuation in systematics. In a related theme, the concept of homeostatic property (...) cluster natural kinds is used to explain why cladistics is well suited to provide a traditional, verbal reference system for the evolutionary properties of species and clades. The advantages of more explicitly probabilistic approaches to phylogenetic inference appear to manifest themselves in situations where evolutionary homeostasis has for the most part broken down, and predictive classifications are no longer possible. (shrink)

Framing systematics as a field consistent with scientific inquiry entails that inferences of phylogenetic hypotheses have the goal of producing accounts of past causal events that explain differentially shared characters among organisms. Linking observations of characters to inferences occurs by way of why-questions implied by data matrices. Because of their form, why-questions require the use of common-cause theories. Such theories in phylogenetic inferences include natural selection and genetic drift. Selection or drift can explain ‘morphological’ characters but selection cannot be causally (...) applied to sequences since fitness differences cannot be directly associated with individual nucleotides or amino acids. The relation of selection to sequence data is by way of downward or top-down causation from those phenotypes upon which selection occurs. The application of phylogenetic inference to explain sequence data is thus restricted to instances where drift is the relevant theory; those nucleotides or amino acids that can be explained via downward causation are precluded from inclusion in the data matrix. The restrictions on the inclusion of sequence data in phylogenetic inferences equally apply to species hypotheses, precluding the more restrictive approach known as DNA barcoding. Not being able to discern drift and selection as relevant causal mechanisms can severely constrain the inclusion and explanations of sequence data. Implications of such exclusion are discussed in relation to the requirement of total evidence. (shrink)

Three competing ‘methods’ have been endorsed for inferring phylogenetic hypotheses: parsimony, likelihood, and Bayesianism. The latter two have been claimed superior because they take into account rates of sequence substitution. Can rates of substitution be justified on its own accord in inferences of explanatory hypotheses? Answering this question requires addressing four issues: (1) the aim of scientific inquiry, (2) the nature of why-questions, (3) explanatory hypotheses as answers to why-questions, and (4) acknowledging that neither parsimony, likelihood, nor Bayesianism are inferential (...) actions leading to explanatory hypotheses. The aim of scientific inquiry is to acquire causal understanding of effects. Observation statements of organismal characters lead to implicit or explicit why-questions. Those questions, conveyed in data matrices, assume the truth of observation statements, which is contrary to subsequently invoking substitution rates within inferences to phylogenetic hypotheses. Inferences of explanatory hypotheses are abductive in form, such that some version of an evolutionary theory(ies) is/are included or implied. If rates of sequence evolution are to be considered, it must be done prior to, rather than within abduction, which requires renaming those putatively-shared nucleotides subject to substitution rates. There are, however, no epistemic grounds for renaming characters to accommodate rates, calling into question the legitimacy of causally accounting for sequence data. (shrink)

The idiom referred to in the title, “don't throw out the baby with the bath water,” instructs us to keep what is essential and to only throw away what is inessential. Bathing babies has the well-being of the child in mind, the end result of which is cleanliness. Efficiency in the task of cleaning is secondary. No one would throw away a baby when draining the baby's bathwater. Somewhat analogously, science and philosophy each have the goal of the attainment of (...) truth in mind. Part and parcel of this search for truth has been the attachment of being parsimonious, especially since William of Ockham. If the goal is truth, then one cannot get lost in the pursuit of parsimony, therefore losing the truth. The goal of finding the truth must remain intact; the method of parsimony at best remains subservient to the attainment of truth. Hans Jonas believed this regarding truth and pursued the criticism of reductive materialism as part and parcel of his research program in philosophy of biology and philosophical anthropology beginning in 1950. In his mind, reductive materialism, as it was practiced, involved the pursuit of parsimony at the cost of the truth through neglect of the purpose-driven conscious life of the subject. In this article, I expose and defend the recovery of certain elements of Aristotelian biology by Professor Hans Jonas. In the process, I show how Jonas was among the early authors writing on the philosophy of biology and defending ontological essentialism and purposefulness in organisms against reductive materialism and the relentless pursuit of the unity of the sciences. Along this line, I position Jonas among the arguments made regarding teleological explanations current in the philosophy of biology. First, I explain and defend Jonas's thesis that a full understanding of organisms requires recognizing an ontological essentialism regarding organisms. Secondly, I explain and defend Jonas's forward looking and backward looking teleological conceptions of activity insofar as it concurs directly with the conscious experience of life for humans, while situating it within the mainstream of philosophy of biology. Last, the importance of this recovery of Aristotelian concepts highlights Jonas's position as an early proponent of non-reductive materialism. More importantly, his thought forces us to recognize that in the pursuit of truth we must use parsimony well. We should take extreme care to preserve the truth; we should not throw out the baby with the bath water. (shrink)

Species pluralism gives us reason to doubt the existence of the species category. The problem is not that species concepts are chosen according to our interests or that pluralism and the desire for hierarchical classifications are incompatible. The problem is that the various taxa we call 'species' lack a common unifying feature.

Most biologists use the Linnaean system for constructing classifications of the organic world. The Linnaean system, however, has lost its theoretical basis due to the shift in biology from creationist and essentialist tenets to evolutionary theory. As a result, the Linnaean system is both cumbersome and ontologically vacuous. This paper illustrates the problems facing the Linnaean system, and ends with a brief introduction to an alternative approach to biological classification.

The Linnaean system of classification is a threefold system of theoretical assumptions, sorting rules, and rules of nomenclature. Over time, that system has lost its theoretical assumptions as well as its sorting rules. Cladistic revisions have left it less and less Linnaean. And what remains of the system is flawed on pragmatic grounds. Taking all of this into account, it is time to consider alternative systems of classification.

This paper takes up the cause of species pluralism. An argument for species pluralism is provided and standard monist objections to pluralism are answered. A new form of species pluralism is developed and shown to be an improvement over previous forms. This paper also offers a general foundation on which to base a pluralistic approach to biological classification.

The issue of whether species are individuals is now an old one; the literature abounds with arguments, counter-arguments and counter-counter-arguments for their individuality. The question I want to take up in this paper is not whether species are indeed individuals, but what ramifications their alleged individuality has for macroevolutionary theory.According to those biologists who argue for a new theory of macroevolution, the individuality of species is one of the fundamental premises of that theory. For example, Joel Cracraft writes of himself (...) and others thatThe issue of individuality… is at the heart of arguments of those evolutionary biologists who see a need to view the patterns and processes of evolution as being hierarchically arranged into microevolutionary and macroevolutionary levels (1987, p. 332). (shrink)