As part of the Darwin anniversary celebrations of 2009, Cambridge University Press issued two new volumes in its well-known series of ‘companions’ to major thinkers. The Cambridge Companion to Darwin (hereafter CCD) came out in a second edition, incorporating all the material in the first edition of 2003, but with two additional chapters, one by the philosopher Simon Blackburn on human nature, the other by the volume's editors, Jonathan Hodge and Gregory Radick, on Darwin's theories in the intellectual long run, from the pre-Socratics forward. The second volume, The Cambridge Companion to the ‘Origin of Species’ (hereafter CCOS), is devoted to the study of Darwin's masterpiece – ‘a work of vital significance and interest’, in the words of editors Michael Ruse and Robert J. Richards, or, as E.O. Wilson has less guardedly put it, ‘the most important book of science ever written’ (CCOS, p. xv).

Unquestionably, the thoroughness of these two Companions will be caviar for professional scholars. But they will also appeal to a wider readership for offering clear and up-to-date expositions of the historical developments and theoretical principles of Darwin's evolutionary thinking. Both volumes treat major issues in the Darwinian literature and, while contributions often emphasize philosophical aspects, historical aspects, including social-historical ones, are far from neglected. Each volume basically follows a twofold division. The CCOS begins with close readings of the topics taken up in the Origin, then moves on to reflections on wider issues raised by the work. In keeping with its title, the CCD provides coverage at once more biographically focused and broader in scope. It deals first with historical issues relating to Darwin's education, achievements and context, then describes the implications of his theory for present-day philosophy, concentrating on the ethical, metaphysical and moral consequences of what could be called ‘Darwinian naturalism’.

For the reader in need of a general overview of Darwin's ‘one long argument’ in the Origin, Hodge and Radick's introduction outlines the farm-and-nature comparisons, contrasts and consequences developed in the first four chapters (CCD, pp. 5–10), while C. Kenneth Waters, in the same volume, looks at how subsequent chapters went on sometimes to argue for the tree of life and sometimes for natural selection, but only infrequently for both together. In the CCOS, analysis of Darwin's argumentation occupies the first half of the volume. Especially notable is Richards's careful consideration of the concept of struggle (CCOS, pp. 62–63) en route to a series of controversial contentions: that, for Darwin, natural selection had a moral purpose; that nature in the 1844 Essay was not a machine but an intelligent force; and that the commonplace notion that Darwin consciously avoided the teleologically loaded word ‘evolution’ is simply wrong. Reading Richards, one is reminded that however much the Origin needs to be read as ‘one long argument’, this is not the case with either of these Companions, where debate flourishes. In the CCOS, Ruse goes so far as to underline, constantly, how some of his statements will no doubt ‘irritate’ his co-editor. (And vice versa, one might add.)

The status of Alfred Russel Wallace as ‘co-discoverer’, and the relationship between Darwin's theory and Malthus's ideas, come up in several chapters, most comprehensively in Radick's (CCD). The Origin's famous diagram is analysed by David Kohn and Philip Sloan in a focused way (CCOS), and by Jean Gayon within a far-ranging perspective which leads on to contemporary challenges (CCD). Darwin's methodological stance and its relationship to the Hershelian doctrine of verae causae and the Whewellian one of consilience are discussed by David Hull (CCD). The question of Darwin's Lamarckianism is treated in various chapters of the CCOS; where Robert Olby reminds us that it was not until the 1870s that the differences between Darwin and Lamarck drew comment from naturalists (p. 35), Mark Largent seeks to distance Darwin from Lamarckian inheritance, to the point where, confronting Darwin's piling up in the Origin of cases of the inheritance of the effects of use and disuse, Largent declares the examples ‘relatively uncommon’ (p. 10). Darwin and religion is addressed by articles in both volumes by John Brooke, and by one in the CCD by Ruse.

Despite such generous coverage, the relative absence of three issues is noteworthy. First, the question of variation, so central to Darwin's theory, is rather downplayed. In the CCOS, Olby's chapter on variation only cursorily evokes the Origin's fifth chapter, dedicated to the ‘laws of variation’. Olby concentrates instead on the briefer treatment in the first chapter. Although Waters in the CCD does not dwell on the fifth chapter either, his presentation of the Origin's various arguments – and the ambiguous meaning of what Darwin misleadingly referred to throughout as ‘my view’ – at least leaves room for attention to the fifth chapter as a challenge to the unity of Darwin's argument.

The second striking absence is the editorial evolution of the Origin. The chapter by Michèle and Chris Kohler in the CCOS deals only with the book's material dimensions. It is curious that many contributions carefully follow Darwin from 1837 until 1859 but then rush through the following twenty-three years. Some contributions focus on later works – such as the 1868 Variation and the 1871 Descent of Man (especially Jim Endersby and Richards in the CCD). But, beyond some remarks by Gayon on when and why the word ‘evolution’ at last entered the Origin (CCD, pp. 179–180), it is difficult to find information on the fate of the Origin after its pristine publication. Morse Peckham's Variorum edition appears to be ‘the great repressed’ in the two volumes – although Sloan in the CCOS (p. 83) reminds us that 75 per cent of the text was modified.

Accordingly, less space is given over than one might expect to evolutionary theorizing before and after 1859. There are a few lines here and there regarding Darwin and Romantic transcendentalist morphology, and concerning translations of the Origin. Overall, however, these two Companions, in their obsession with Darwin's ‘big idea’, effectively marginalize evolutionary debate of other types which was happening in France, Germany and Italy – though Hodge and Radick, with their new chapter in the CCD, giving a synthetic overview of origins-and-species traditions and Darwin's singularity within them, have gone some way towards remedying the omissions in that volume.

In spite of these minor shortcomings (the programme of a third Companion?), these volumes are undeniably a great introduction to Darwin, his ideas and his legacies. With the wealth of historical and philosophical analyses, and the great variety of contributions covering major problems within the field, they constitute an indispensable tool for any teacher or student of Darwin and Darwinism. The general public will find a complete presentation of Darwin's thinking, while the scholarly can enjoy a number of revisionist claims sure to provoke responses, critical and otherwise. Hodge and Radick's statement of purpose can stand for both volumes: not to be encyclopedic, but to offer ‘a sample of historical and philosophical interpretations of Darwin and Darwinism’ in the name of ‘better informed debate about Darwin and his influence – what it has been, and what, in a future full of other philosophical options, it should be’ (CCD, p. 17).