Robert J. O'Hara

Institutions of higher education in the United States are remarkably diverse in their educational purposes, their organizational structure, and their architectural styles. But underlying all this diversity are two distinct historical models: the decentralized British "collegiate" model of university education, and the centralized Germanic university model. Early American higher education grew out of the British collegiate tradition and emphasized the comprehensive development of students' intellect and character, while the Germanic university tradition, introduced in the late 1800s, shifted the focus to technical scholarship and research. The Germanic university model held sway for much of the twentieth century, but there is now a widespread renewal of interest in the older decentralized British collegiate model, and in universities across the United States and around the world, small "residential colleges" like those at Oxford and Cambridge are now being planned and built. These residential colleges or "houses" (as they are sometimes called) provide small, stable, faculty-led, home-like environments for a few hundred students each, and their social and architectural design seeks to counteract the impersonal bureaucratic experience that students often have in large Germanic-style universities. This revival of the collegiate model of university organization is one of the most important trends in the design of educational communities in the world today.

138 titles across a wide range of scholarly publications illustrate the conceptual affinities that connect the palaetiological sciences of biological systematics, historical linguistics, and stemmatics. These three fields all have as their central objective the reconstruction of evolutionary "trees of history" that depict phylogenetic patterns of descent with modification among species, languages, and manuscripts. All three fields flourished in the nineteenth century, underwent parallel periods of quiescence in the early twentieth century, and in recent decades have seen widespread parallel revivals. "Tree thinking" (O'Hara, 1988) is now standard within evolutionary biology, and the unity of what William Whewell called palaetiology is being once again appreciated by scholars and scientists in many fields.

Two new modes of thinking have spread through systematics in the twentieth century. Both have deep historical roots, but they have been widely accepted only during this century. Population thinking overtook the field in the early part of the century, culminating in the full development of population systematics in the 1930s and 1940s, and the subsequent growth of the entire field of population biology. Population thinking rejects the idea that each species has a natural type (as the earlier essentialist view had assumed), and instead sees every species as a varying population of interbreeding individuals. Tree thinking has spread through the field since the 1960s with the development of phylogenetic systematics. Tree thinking recognizes that species are not independent replicates within a class (as earlier group thinkers had tended to see them), but are instead interconnected parts of an evolutionary tree. It lays emphasis on the explanation of evolutionary events in the context of a tree, rather than on the states exhibited by collections of species, and it sees evolutionary history as a story of divergence rather than a story of development. Just as population thinking gave rise to the new field of population biology, so tree thinking is giving rise to the new field of phylogenetic biology.

In the last thirty years systematics has transformed itself from a discipline concerned with classification into a discipline concerned with reconstructing the evolutionary history of life. This transformation has been driven by cladistic analysis, a set of techniques for reconstructing evolutionary trees. Long interested in the large-scale structure of evolutionary history, cladistically oriented systematists have recently begun to apply "tree thinking" to problems near the species level. ¶ In any local ("non-dimensional") situation species are usually well-defined, but across space and time the grouping of populations into species is often problematic. Three views of species are in common use today, the biological species concept, the evolutionary species concept, and the phylogenetic species concept. Each of these has strengths and weaknesses, but no matter which is applied, exact counts of the number of species in any extended area will always be ambiguous no matter how much factual information is available. This ambiguity arises because evolution is an historical process, and the grouping of organisms into species always depends to some extent upon expectations of the future behavior of those organisms and their descendants, expectations that cannot be evaluated in the present. The existence and special character of the species problem is itself one of the central pieces of evidence for evolution.

Chauncey Wright (1830–1874) was one of the first American philosophers to explore the implications of Charles Darwin's work in evolutionary biology. Wright became a strong supporter of the idea of natural selection and a strong critic of the anti-selectionist and teleological arguments of St. George Jackson Mivart and Herbert Spencer, and he laid the groundwork for the field that is today called evolutionary epistemology. As the mentor of the original Cambridge "Metaphysical Club" (William James, Charles Sanders Peirce, and Oliver Wendell Holmes, Jr.), Wright was also instrumental in the development of the American school of Pragmatism. Although his analytical brilliance was widely acknowledged, he never became professionally successful, and he died in 1874 in his 45th year.

William Whewell (1794–1866), polymathic Victorian scientist, philosopher, historian, and educator, was one of the great neologists of the nineteenth century. Although Whewell's name is little remembered today except by professional historians and philosophers of science, researchers in many scientific fields work each day in a world that Whewell named. "Miocene" and "Pliocene," "uniformitarian" and "catastrophist," "anode" and "cathode," even the word "scientist" itself—all of these were Whewell coinages. Whewell is particularly important to students of the historical sciences for another word he coined, one that was unfortunately not as successful as many of his others because it is difficult to pronounce. This word, "palaetiology," was the name Whewell gave to the class of sciences that are concerned with historical causation: the class we might today refer to as historical sciences. Although the disciplines Whewell included under the heading of palaetiology might seem to cut across conventional academic boundaries of his day and ours—his exemplary palaetiological sciences were geology and comparative philology—all these fields may be examined together, Whewell argued, because of their common interest in reconstructing the past. ¶ This paper is an essay in the palaetiological sciences, dedicated to Whewell on the bicentennial of his birth, an essay that examines some of the principles, maxims, and rules of procedure that these sciences have all in common. Its first purpose is to demonstrate the continuing validity of Whewell's classification of these sciences through a study of historical representation in three different palaetiological fields: systematics, historical linguistics, and textual transmission. Its second purpose is to continue the development of an extended analogy between historical representation and cartographic representation that I began in an earlier paper (O'Hara, 1993, Systematic Biology), an analogy that makes especially clear the common representational practices that are found throughout palaetiology.

Accounts of the evolutionary past have as much in common with works of narrative history as they do with works of science. Awareness of the narrative character of evolutionary writing leads to the discovery of a host of fascinating and hitherto unrecognized problems in the representation of evolutionary history, problems associated with the writing of narrative. These problems include selective attention, narrative perspective, foregrounding and backgrounding, differential resolution, and the establishment of a canon of important events. The narrative aspects of evolutionary writing, however, which promote linearity and cohesiveness in conventional stories, conflict with the underlying chronicle of evolution, which is not linear, but branched, and which does not cohere, but diverges. The impulse to narrate is so great, however, and is so strongly reinforced by traditional schemes of taxonomic attention, that natural historians have more often abandoned the diverging tree than they have abandoned the narrative mode of representation. If we are to understand the true nature of the evolutionary past then we must adopt tree thinking, and develop new and creative ways, both narrative and non-narrative, of telling the history of life.

This well-written volume is an introduction, not to world history, but to the special genre of "Big History," as the subtitle indicates. Christian and his fellow big historians, reacting against popular scepticism toward "master narratives," seek to create a new class of grand works that incorporate not only the history of human society, but also of the Earth, its life, and the universe as a whole. Specialists in any of the fields covered by the volume may find rough spots in the treatment of topics they know well, but given the scope of the effort I think it is fair to regard this as something like the first edition of a continuing work. Later editions would be strengthened—as would the Big History movement as a whole—by explicitly incorporating some discussion of teleological reasoning in science, and by deploying clear distinctions between processes that are teleomatic (such as star formation), teleonomic (such as organismal development), and classically teleological (such as intentional behaviour on the part of humans). In "Maps of Time," David Christian has given us a book full of interesting facts, and with ideas to argue for and against in every chapter. It should provoke lively discussion across a whole range of academic disciplines.

"The Natural System" is the abstract notion of the order in living diversity. The richness and complexity of this notion is revealed by the diversity of representations of the Natural System drawn by ornithologists in the Nineteenth Century. These representations varied in overall form from stars, to circles, to maps, to evolutionary trees and cross-sections through trees. They differed in their depiction of affinity, analogy, continuity, directionality, symmetry, reticulation and branching, evolution, and morphological convergence and divergence. Some representations were two-dimensional, and some were three-dimensional; n-dimensional representations were discussed but never illustrated. The study of diagrammatic representations of the Natural System is made difficult by the frequent failure of authors to discuss them in their texts, and by the consequent problem of distinguishing features which carried meaning from arbitrary features and printing conventions which did not. Many of the systematics controversies of the last thirty years have their roots in the conceptual problems which surrounded the Natural System in the late 1800s, problems which were left unresolved when interest in higher-level systematics declined at the turn of this century.

80 titles published between 1965 and 1996 in multiple languages attest to an increase in scholarly interest in the history of systematic biology, both among scientific practitioners and also among historians and philosophers of science. Topics studied have included the early history of the field (Ray, Linnaeus, Buffon), the influence of essentialism on systematics, the history of systematic diagrams, the development of cladistic analysis, the nature of species, and the growth of phylogenetic thinking.

James Valentine's "On the Origin of Phyla" is divided into three main sections: "Evidence of the Origins of Metazoan Phyla," "The Metazoan Phyla," and "The Evolution of the Phyla." The second section is the zoological core of the book, a more or less conventional treatment of major animal taxa, arranged in chain-of-being fashion from sponges to cnidarians to "worms" of many kinds, and so onward to arthropods, echinoderms, chordates, and all others in between. Philosophically inclined readers will be most interested in the first and third sections of the volume, which treat phylogenetic principles and macroevolution respectively. These sections are rich in detail, but Valentine adopts something of a rear-guard position on many issues, arguing in favor of a number of concepts that most systematists have now abandoned. The publisher's advertisement describes "On the Origin of Phyla" as "one of the classic scientific texts of the twentieth century," and for us in the 21st century, that may be the best way to regard it. It will be of greatest value to zoologists who want a good compendium of current comparative data, and to historians and philosophers of science who have an interest in the complex development of phylogenetic "tree-thinking" in systematic biology.

The species problem is one of the oldest controversies in natural history. Its persistence suggests that it is something more than a problem of fact or definition. Considerable light is shed on the species problem when it is viewed as a problem in the representation of the natural system (sensu Griffiths, 1974, Acta Biotheor. 23: 85–131; de Queiroz, 1998, Philos. Sci. 55: 238–259). Just as maps are representations of the earth, and are subject to what is called cartographic generalization, so diagrams of the natural system (evolutionary trees) are representations of the evolutionary chronicle, and are subject to a temporal version of cartographic generalization which may be termed systematic generalization. Cartographic generalization is based on judgements of geographical importance, and systematic generalization is based on judgements of historical importance, judgements expressed in narrative sentences (sensu Danto, 1985, Narration and knowledge, Columbia Univ. Press, New York). At higher systematic levels these narrative sentences are conventional and retrospective, but near the "species" level they become prospective, that is, dependent upon expectations of the future. The truth of prospective narrative sentences is logically indeterminable in the present, and since all the common species concepts depend upon prospective narration, it is impossible for any of them to be applied with precision.

Stephen Edelston Toulmin has been one of the most wide-ranging scholars of the twentieth century. He has written extensively on the history and philosophy of the physical, biological, and historical sciences, as well as on logic, ethics, and rhetoric. This listing of more than 100 publications by and about Toulmin is intended to encourage those scholars who may have come to Toulmin's work from only one direction to explore the full range of his research and writing across many different disciplines.

Classifications of animals and plants have long been represented by hierarchical lists of taxa, but occasional authors have drawn diagrammatic versions of their classifications in an attempt to better depict the "natural relationships" of their organisms. Ornithologists in 19th-century Britain produced and pioneered many types of classificatory diagrams, and these fall into three groups: (a) the quinarian systems of Vigors and Swainson (1820s and 1830s); (b) the "maps" of Strickland and Wallace (1840s and 1850s); and (c) the evolutionary diagrams of the post-Darwin authors (1860 on). The quinarians distinguished between affinity and analogy and used both in their classifications, whereas Strickland rejected the quinarians' belief in numerical regularity and their use of analogy. Wallace's "maps" are easily given an evolutionary interpretation, and his approach was taken up and modified by later evolutionary anatomists. Sharpe returned to Strickland's methods and merely appended a superficial evolutionary interpretation. Contrary to common belief systematics has a rich conceptual history, and many of the conceptual developments in 19th-century systematics were made by ornithologists.

"The Natural System" is the name given to the underlying arrangement present in the diversity of life. Unlike a classification, which is made up of classes and members, a system or arrangement is an integrated whole made up of connected parts. In the pre-evolutionary period a variety of forms were proposed for the Natural System, including maps, circles, stars, and abstract multidimensional objects. The trees sketched by Darwin in the 1830s should probably be considered the first genuine evolutionary diagrams of the Natural System—the first genuine evolutionary trees. Darwin refined his image of the Natural System in the well-known evolutionary tree published in the Origin of Species, where he also carefully distinguished between arrangements and classifications. Following the publication of the Origin, there was a great burst of evolutionary tree building, but interest in trees declined substantially after 1900, only to be revived in recent years with the development of cladistic analysis. ¶ While evolutionary trees are modern diagrams of the Natural System, they are at the same time instances of another broad class of diagrams that may be called "trees of history": branching diagrams of genealogical descent and change. During the same years that Darwin was sketching his first evolutionary trees, the earliest examples of two other trees of history also appeared: the first trees of language evolution and of manuscript genealogy. Though these were apparently independent of evolutionary trees in their origin, the similarities among all these trees of history, and among the historical processes that underlie them, were soon recognized. Darwin compared biological evolution and language evolution several times in the Origin of Species, and both Ernst Haeckel and the linguist August Schleicher made similar comparisons. Both linguists and stemmaticists (students of manuscript descent) understood the principle of apomorphy—the principle that only shared innovations provide evidence of common ancestry—more clearly than did systematists, and if there had been more cross-fertilization among these fields the cladistic revolution in systematics might well have taken place in the nineteenth century. ¶ Although historical linguists and stemmaticists have in some respects had sounder theory than have systematists, at least until recently, they have also had the practical problem of very large amounts of data, a problem not often faced by systematists until the advent of molecular sequencing. The opportunity now exists for systematists to contribute to the theory and practice of linguistics and stemmatics, their sister disciplines in historical reconstruction, through application of our commonly used computer programs for tree estimation. Preliminary results from the application of numerical cladistic analysis to a large stemmatic data set have been very encouraging, and have already generated much discussion in the stemmatics community.

Discussions of the theory and practice of systematics and evolutionary biology have heretofore revolved around the views of philosophers of science. I reexamine these issues from the different perspective of the philosophy of history. Just as philosophers of history distinguish between chronicle (non-interpretive or non-explanatory writing) and narrative history (interpretive or explanatory writing), I distinguish between evolutionary chronicle (cladograms, broadly construed) and narrative evolutionary history. Systematics is the discipline which estimates the evolutionary chronicle. ¶ Explanations of the events described in the evolutionary chronicle are not of the covering-law type described by philosophers of science, but rather of the how-possibly, continuous series, and integrating types described by philosophers of history. Pre-evolutionary explanations of states (in contrast to chroniclar events) are still widespread in "evolutionary" biology, however, because evolutionary chronicles are in general poorly known. To the extent that chronicles are known, the narrative evolutionary histories based on them are structured like conventional historical narratives, in that they treat their central subjects as ontological individuals. This conventional treatment is incorrect. The central subjects of evolutionary narratives are clades, branched entities which have some of the properties of individuals and some of the properties of classes. Our unconscious treatment of the subjects of evolutionary narratives as individuals has been the cause of erroneous notions of progress in evolution, and of views that taxa "develop" ontogenetically in ways analogous to individual organisms. We must rewrite our narrative evolutionary histories so that they properly represent the branching nature of evolution, and we must reframe our evolutionary philosophies so that they properly reflect the historical nature of our subject.