Twentieth-century attempts to evaluate the philosophical significance of Darwinism have been dominated by a pair of polar perspectives. At one extreme stand those who insist on the autonomy of philosophy and who conclude, with the early Wittgenstein, that 'Darwin's theory has no more to do with philosophy than any other hypothesis in natural science.' At the other extreme are naturalists who maintain that 'now that we know' this or that other fact about the cosmos, the human brain, or (most pertinently for present purposes) the role of natural selection in hominid evolution, traditional philosophical problems are easily solved. Each opponent lives off the excesses of the other. Both also overlook the possibility that scientific ideas, including Darwin's, might play a useful, but partial, role in a variety of philosophical discussions. It has proved remarkably difficult to give Darwin his due. Philosophers drawn to the Wittgensteinian pole typically assume that there are concepts and methods whose application to philosophical questions is unaffected by the deliverances of any science, even a science that might transform ideas about life and mind. Their discussions of questions in metaphysics, epistemology and ethics take over the idioms in which traditional philosophy has posed them, often without appreciating the fact that the language they employ was developed in response to a scientific picture that has long been superseded.

Some scientific thinkers, while not themselves philosophers, make philosophers necessary. Charles Darwin is an obvious case. His conclusions about the history and diversity of life - including the evolutionary origin of humans - have seemed to bear on fundamental questions about being, knowledge, virtue and justice. Are we different in kind from other animals? Do our apparently unique capacities for language, reason and morality point to a divine spark within us, or to ancestral animal legacies still in evidence in our simian relatives? What forms of social life are we naturally disposed towards - competitive and selfish forms, or cooperative and altruistic ones? Once we adopt a Darwinian perspective, moreover, how should we respond to such venerable doctrines of the Western tradition as Aristotle's essentialism, Descartes' dualism of body and mind and Kant's rejection of the very possibility of a natural science of the mind? The Cambridge Companion to Darwin aims to facilitate understanding of such issues. It provides an introduction to Darwin's thinking and to the various and often contentious uses made of his legacies today. To serve these ends, the volume departs somewhat from the precedents of earlier volumes in this series. The chapters come in four clusters, two broadly historical and two broadly philosophical.

“The law of the succession of types, although subject to some remarkable exceptions, must possess the highest interest to every philosophical naturalist.” / When Charles Darwin penned these lines in 1837, he was twenty-eight years old, fresh from the Beagle voyage, and a self-described 'philosophical naturalist'. As such, he was engaged neither in natural history nor in natural philosophy. Natural history, in the tradition of the Swedish botanist Linné (Linnaeus), concerned the systematic ordering of animals and plants and the discovery of new species. Natural philosophy, in the tradition of Descartes and Newton, concerned the search for general physical laws. Darwin was aligning himself with investigators whose work fell outside these traditions. Some were interested in a comparative anatomy based on ideal forms - the so-called 'transcendental' anatomists, such as the French zoologist Etienne Geoffroy Saint-Hilaire and his Scottish disciple Robert Knox. Others, such as the geologist Charles Lyell, were interested in building comprehensive theories about the earth and its inhabitants. Philosophical naturalists spoke of various 'laws of life'. They debated the existence of laws, for example, said to relate taxonomic groupings in regular circular arrangements, as in the so-called quinarian system, or to govern organic functions such as the development of the embryo. Another law under discussion was the law of the succession of types.

Machines, competition, empire and progress fascinated the Victorians. One of the most famous scientific theories of the era, Charles Darwin's theory of natural selection, tells of machine-like organisms that compete, colonise and improve. To notice resemblances such as these, between the context of Darwin's theory and its content, is nothing new. In 1862, Karl Marx, in a letter to his collaborator Friedrich Engels, wrote: 'It is remarkable how Darwin recognises among beasts and plants his English society with its division of labour, competition, opening up of new markets, “inventions”, and the Malthusian “struggle for existence”. It is Hobbes' “bellum omnium contra omnes” [“the war of all against all”].' In our own day, debates over the cultural conditioning of scientific knowledge have made this old insight newly problematic. This chapter attempts to clarify these new problems. Drawing on recent thinking about culture and science, it looks at how Darwin's social, material and intellectual culture conditioned the form and content of his theory of natural selection. One view may be dispensed with at the start: that Darwin developed the theory of natural selection because he was a genius, and, since geniuses do not belong to mundane history like most people, it is pointless to ask about the cultural conditioning of his theory.

Like Darwin's own theory of evolution, the modern Darwinian theory of evolution has two main elements: “The Tree of Life: All organisms now alive on earth trace back to a common ancestor. / Natural Selection: Natural selection has been an important cause of the similarities and differences that exist in the earth's biota.” / The first of these propositions says that any two contemporary organisms have a common ancestor. Human beings are genealogically related to each other, but each human being also has a common ancestor with chimps, dogs, clams, daffodils, bacteria and yeast. The second proposition, as I have formulated it, does not say that natural selection is the only cause of evolution. Indeed, it should be understood to leave open the possibility that there are traits for which natural selection is entirely irrelevant. This is the big picture, and evolutionary biology is devoted to filling in the details. Although Darwinism is easy to describe, this simple theory gives rise to a rich range of metaphysical and epistemological questions. It is the purpose of this chapter to discuss some of them. In conformity with the structure of Darwinian theory, I have chosen one metaphysical and one epistemological problem from each of the two big ideas.

“All the sentiments of the human mind, gratitude, resentment, love, friendship, approbation, blame, pity, emulation, envy, have a plain reference to the state and situation of man, and are calculated for preserving the existence and promoting the activity of such a being in such circumstances.” Hume, Dialogues Concerning Natural Religion (1779), part 3, Section 13 / It is quite common for philosophers, if not biologists, assessing the impact of Darwin on our views about human nature to associate him with Hume. Owen Flanagan even talks of a 'Humean-Darwinian' picture of human nature. In this chapter I want to chart the relation in some detail. The result is not to disrupt the marriage but to suggest, with more precision than usual, how close and how fertile it actually is. / Human Nature / By 'human nature' we generally denote not our bare animal construction - two eyes, four limbs, one head, upright gait and so on - but our rather more exciting psychological traits. Theorists of human nature are particularly concerned with our cognitive and motivational dispositions and capacities, the subjects of Hume's Treatise of Human Nature (1739).

Among philosophers, naturalism is the view that contemporary scientific theory is the source of solutions to philosophical problems. Naturalists look to the theory of natural selection as a primary resource in coming to solve philosophical problems raised by human affairs in particular. For the theory combines relevance to human affairs and scientific warrant more strongly than does any other theory. Theories in physics and chemistry may be more strongly confirmed, especially because their more precise predictions can be tested in real time. But these theories have little to tell us about human conduct and institutions. On the other hand, actual and possible theories in the social and behavioural sciences may in the future have more to tell us about humanity than Darwinian theory; but these theories do not as yet have anything like the degree of confirmation of Darwin's theory. This chapter surveys contemporary strategies for providing a Darwinian understanding and vindication of morality, ethical norms, our conception of justice, and the cooperative human institutions which those norms and conceptions underlie. We will see that while the prospects for a Darwinian vindication of moral claims - as true or well founded - remain clouded, the prospects for explaining the normative dimension of human affairs by appeal to Darwinism appear to be improving.

Reading On the Origin of Species is a rite of passage for many biologists and its reasoning continues to play a pivotal role in biological thought. It is often said, following Darwin himself, that the Origin is 'one long argument' (459). There is something important in this remark. Readers expecting the Origin to be structured around a narrative account find the book perplexing. Unlike the paradigmatic early Victorian book on evolution, the Edinburgh journalist Robert Chambers' Vestiges of the Natural History of Creation, published anonymously in 1844, the Origin was not written as a history of life's evolution on earth. Rather, the Origin was structured as an argument. Hence, Darwin's insistence that his book was one long argument provides an indispensable clue for reading the text. But it is not clear that it should be read as one argument. Although Darwin may have designed his book to be read as one long argument for evolution by means of natural selection, many of his readers must have read it differently. We know this because the Origin persuaded many readers to accept the 'evolution' idea but not the 'by means of natural selection' part of Darwin's view. These readers were not swayed by one long argument for evolution by means of natural selection. So, to understand the reasoning that influenced Darwin's readers, it is better to think of the Origin as a body of argumentation flexible enough to allow readers' views of the reasoning to differ from what Darwin might have intended. The aim of this chapter is to provide a guide to the Origin's flexible and sometimes elusive body of reasoning.

In 1909, as part of the celebrations commemorating Charles Darwin's birth in 1809 and the publication of his Origin of Species in 1859, the American pragmatist philosopher John Dewey gave a lecture at Columbia University on 'the influence of Darwinism on philosophy'. As printed the following year, his text begins: “That the publication of the 'Origin of Species' marked an epoch in the development of the natural sciences is well known to the layman. That the combination of the very words origin and species embodied an intellectual revolt and introduced a new intellectual temper is very easily overlooked by the expert. The conceptions that had reigned in the philosophy of nature and knowledge for two thousand years, the conceptions that had become the familiar furniture of the mind, rested on the assumption of the superiority of the fixed and final; they rested upon treating change and origin as signs of defect and unreality. In laying hands upon the sacred ark of absolute permanency, in treating the forms that had been regarded as types of fixity and perfection as originating and passing away, the 'Origin of Species' introduced a mode of thinking that in the end was bound to transform the logic of knowledge, and hence the treatment of morals, politics, and religion.” / For Dewey, what Darwinian science replaced was a Greek philosophy of nature that, as he presented it, had dominated unchallenged from the days of Plato and Aristotle, namely the doctrine that fixed, purposive natures - specific forms (eide) - are what are fully real and truly knowable.

For nearly one-and-a-half centuries, biologists interested in evolution have been haunted by the question of whether their conceptions are or are not 'Darwinian'. While it may not be unique, this persistent positioning of new developments in relation to a single, pioneering figure is quite exceptional in the history of modern natural science. Physicists currently working in the domains of relativity or quantum theory may refer sometimes to Einstein or Bohr; but their debates are not massively structured by this reference as evolutionary theory has been and remains structured by reference to Darwin. A proximate cause of Darwin's enduring presence is that evolutionary biologists have never stopped reading him. The remarkably numerous editions and translations of Darwin's books have in themselves helped to make this possible. But the availability of key texts only takes us so far in understanding why evolutionary biologists go on reading Darwin, referring to him, feeling the necessity of labelling their theories as 'Darwinian' or 'non-Darwinian' or 'anti-Darwinian'. Indeed, on the face of it, there are compelling reasons for modern biologists to avoid affiliating their work with Darwin's. Darwinism does not belong only to the history of science; it also belongs to cultural and political history. Among other things, neo-liberal economics, social Darwinism, racial anthropology, Nazi ideology and the materialistic monism of Darwin's German supporter Ernst Haeckel had strong interactions with Darwinism in the first century of its history.

The period of 1933–59 brought forth several improvements in the study of comets, which led to more discoveries and longer periods of visibility. The greatest advances came in the area of telescopes and photography.

Comet discoveries

The USA continued its dominance in discovering comets during this period, with amateur and professional astronomers being given official credit for 60 discoveries. Following the USA were South Africa (24 discoveries), Slovakia (19 discoveries), Japan (9 discoveries), Russia (8 discoveries), and Finland (7 discoveries).

The most prolific comet discoverer of this period was A. Mrkos (Slovakia), who found 11 new comets. Next in line were M. Honda (Japan) and L. C. Peltier (USA), who each found 7 new comets, M. J. Bester (South Africa), who found 6, and R. Burnham Jr. (USA) and D. du Toit (South Africa), who each found 5. Honda and Peltier were both amateur astronomers, while Burnham discovered comets as both an amateur and a professional astronomer.

Another important point concerning comets discovered during this period was that many were found during surveys. The most successful were the National Geographic–Palomar Observatory Sky Survey, which found 11 comets during the period of 1949–55, and the Skalnaté Pleso binocular comet search program, which found 19 comets during the period of 1948–59.

Comet observations

Several very active comet observers mentioned in Cometography volume 3 continued to observe during most, if not all, of the period covered by this volume. The most notable include G. van Biesbroeck, H. M. Jeffers, and M. Beyer.

1. C/1933 D1Discovered: 1933 February 16.1 (Δ = 0.60 AU, r = 1.01 AU, Elong. = 75°)

2. (Peltier)Last seen: 1933 April 14.21 (Δ = 1.52 AU, r = 1.49 AU, Elong. = 68°)

3. Closest to the Earth: 1933 February 23 (0.5575 AU)

4. 1933 I = 1933aCalculated path: CEP (Disc), CAS (Feb. 17), PER (Feb. 23), TAU (Mar. 8), ORI (Mar. 18)

L. C. Peltier (Delphos, Ohio, USA) was involved in a routine comet-sweeping session on 1933 February 16.1, when he came across an object of magnitude 8.6 at α = 22h 48m, δ = +62°. He immediately wired G. van Biesbroeck (Yerkes Observatory, Wisconsin, USA) for confirmation, but cloudy skies were prevalent. Peltier sent a telegram to Harvard College Observatory (Massachusetts, USA) the next morning announcing his discovery. Confirmation came on February 17.05, when van Biesbroeck detected the comet in hazy skies. He described it as 9th magnitude, with a round centrally condensed coma 5′ across. H. M. Jeffers (Lick Observatory, California, USA) independently confirmed the comet with the 30-cm refractor on February 17.23. He estimated the magnitude as 9, and said the centrally condensed coma was 2′ across, but contained no stellar nucleus. Additional confirmation came on February 17.81, when R. Carrasco (Madrid Observatory, Spain) estimated the photographic magnitude as 8. The comet attained its most northerly declination of +62° on February 17. The comet was discovered a few days after it had passed perihelion, but was approaching Earth.