Ian Duncan's work focuses on the eighteenth and nineteenth centuries, when both novels and natural philosophy viewed humanity as a subject of investigation. Duncan states that his work was inspired by Nancy McLane's Romanticism and the Human Sciences (2000) and attempts to do for novels what McLane's work did for poetry. After an introduction, Duncan's work has two philosophical chapters (1, 3) and three worked-example chapters (2, 4, 5), with notes and bibliography comprising around a hundred of the three hundred pages of this monograph.

Chapter 1 focuses on the 1780s debate between Kant and Herder over whether human nature finds ‘its vocation only in the species but not in the individual’ (p. 33). Duncan notes that one of Kant's criticisms of Herder was that his arguments on the natural history of man were fictional, in that they relied more on imagination and poetry than on philosophical analysis. This charge of natural history being a fusion of fact and fancy continued throughout the period as practitioners such as Buffon and Rousseau strove to show they were knowledge producers rather than inventors even as they adopted fictional tropes. As Duncan argues, ‘Kant's critical reason may have won the local engagement … but Herder's flight into conjecture, charging the natural history of man with a biological drive, would seem to have won the war’ (p. 52).

Chapter 2 then focuses on how these ideas were taken up in Goethe's Wilhelm Meister's Apprenticeship (1795–1796), Stäel's Corinne, or Italy (1807) and Scott's Waverley (1814). In the novel Wilhelm Meister, Goethe follows the development of a man and his discovery of a vocation according to purely human means. Duncan brings out the sexism implicit in the period's equating of humanity with men but not with women (see also Dorothy L. Sayers's 1938 essay Are Women Human?). Stäel sought to correct this sexism by taking one of the women Goethe had used to develop Wilhelm and placed her as the heroine of her novel Corinne. However, Duncan notes that Corinne ‘narrates a collision between the ideals of Bildungsroman and a hardening repertoire of novelistic topoi – masculine vocation, national destiny, the marriage plot – as these are coalescing into a set of norms for nineteenth-century practice’ (p. 57). Scott took another path: he used national history from the recent past as the developmental force for another impressionable man, Edward Waverley. For Scott, national history mediated the natural and personal histories, which therefore enabled it to resolve the tension between the individual and species ‘by recasting [this tension] as an empirical discrepancy between temporal states’ (p. 73).

Chapter 3 focuses on the figure of the orangutan as the focus for the debates around species change and the formation of human nature. Lamarck's Zoological Philosophy (1809) had been reprinted following the dispute between Cuvier and Geoffroy Saint-Hilaire over whether morphological variation was to be explained functionally or by transformism. As Duncan notes, the Kant–Herder fault lines were being reused with one (Cuvier) charging the other (Geoffroy) of ‘forsaking properly scientific procedure and resorting to literary tricks of analogy and conjecture’ (p. 92). The orangutan appeared in a number of novels at this time and Duncan focuses on Scott's Count Robert of Paris (1831) with Sylvan, an eight-foot-tall orangutan inspired by Frankenstein's monster, and Hugo's Notre-Dame de Paris (1831) with his character Quasimodo, a ‘monster’ (p. 88) worthy of study by Geoffroy. By the end of Notre-Dame, Quasimodo is the most human of them all, whereas Sylvan displays many human traits and passions despite being an orangutan. Both authors leave their readers asking what, if anything, makes humanity unique or unified.

Chapter 4 focuses on a single novel by Dickens, Bleak House (1853), and Dickens's use of transformist theories in the creation of his characters (or monsters). Duncan notes Dickens's approval of Chambers's Vestiges of the Natural History of Creation (1844), in terms of both its ideas and its style, mixing facts with conjectural flourishes. In Bleak House, Duncan argues, Dickens has no human characters, but everyone is deformed in some way by their circumstances. Duncan provides snippets from the cast of character–monsters to prove his point: a longer worked example would clinch the argument. Chapter 5 concludes by reviewing Eliot's The Mill on the Floss (1860), Middlemarch (1872) and Daniel Deronda (1876) to highlight Eliot's use of scientific vocabulary. For The Mill on the Floss, Duncan highlights that the heroine is the one with the greatest species consciousness, rather than the surrounding men; in Middlemarch, Eliot dramatizes the moment of understanding by arguing that literal technical terms facilitate the imaginative, which enables comprehension of theories; in Daniel Deronda, Eliot makes use of the pangenesis hypothesis to explain how Daniel felt so attuned to his Jewish racial heritage. Duncan concludes his work with Eliot's ‘Shadows of the Coming Race’ (1879), in which evolutionary processes produce creatures without consciousness or life.

Running in the background, with occasional appearances, is the question of theology or world view. Much of the material covered by Duncan can be seen as a reaction against Christianity. Put simply, the Christian world view sees humans as both creatures (not unique) and image bearers of God (unique). When any of Duncan's protagonists sought to remove God from their theories of humanity, they removed the uniqueness bestowed on humanity by being God's image bearers. However, the thought of only being a creature, and not unique, so troubled Buffon and Rousseau that they attempted to reconstruct a uniqueness for humanity apart from God (pp. 37, 41–43). The Lutheran Cuvier founded a Bible society, Scott was an ordained Presbyterian elder, Dickens was a liberal Anglican, whereas Eliot translated German higher criticism and Geoffroy was a deist. It would be well worth a future project to explore these connections between a priori world views and approaches to the natural history of humanity, but that would make for another book.

In conclusion, Duncan's work is readable and well researched, with Chapters 1 to 3 being particularly strong in demonstrating the interplay between natural philosophy, fiction, facts and imagination.