Gregory Claeys, familiar to many readers for his incisive studies of radical and utopian political thought, advances in Imperial Sceptics: British Critics of Empire, 1850–1920 an important, revisionist study of the rise and development of anti-imperial ideas in Britain. Beginning his account in the 1850s, much earlier than most studies that tend to take the 1902 publication of J. A. Hobson's Imperialism: A Study as their starting point, Claeys argues that Positivists in Britain formulated an early, forceful, and overlooked critique of empire that set the framework for later socialist opposition to empire and indeed for the “relativistic humanitarianism” of the present day. As early as the 1850s, Frederic Harrison, Richard Congreve, and others were developing an economic analysis of imperialism and defining in contrast an “ideal foreign policy” that went beyond the old radicalism of Cobden and Bright and the Manchester School. Frederic Harrison outlined a humanitarian international policy that rejected both Christianity and the rhetoric of civilization to legitimate empire; he regarded both these perspectives as dangerously exclusionary. A leading member of the Jamaica Committee and active in numerous other groups and campaigns, Harrison wrote and campaigned extensively over sixty years against British imperial involvement in Turkey, Afghanistan, India, Egypt, and South Africa, returning consistently to his central contention that a “military terrorism” masqueraded in the guise of civilizational uplift and that financial speculators drove imperial policy in the interests of profit and usury. He and other Positivists extended Comte's global vision of a federation of small states to support home rule in Ireland, India, and elsewhere and applied the version of Comte's Religion of Humanity to command respect for all cultures and races, on the grounds of a shared humanity. Claeys puts Positivism in the center of Victorian political and intellectual culture, rather than at the fringes, by pinpointing the multiple ways in which Positivism shaped socialist critiques of empire and attempts to define alternatives to empire.

In the central section of the book, Claeys examines a wide spectrum of socialists and argues that turn-of-the-century socialists were much more ambivalent about empire and much less uniformly opposed to it than is often supposed. Their widespread moral indignation about imperial territorial expansion mingled in many cases with a determination to improve empire rather than abandon it. Socialists were united in their opposition to a capitalist imperialism in which government policy was determined by financial interests and lobbies motivated by profit but divided in their views of a noncapitalist or “socialist imperialism.” The ideal of a “socialist commonwealth,” defended on utilitarian grounds, gained wide acceptance among socialists, notably H. Hyndman, Keir Hardie, and Ramsay Macdonald. The book culminates in an important revisionist reading of J. A. Hobson that departs from the prevalent emphasis on the Cobdenite flavor of imperialism to emphasize instead that the book also grew out of socialists’ debates about empire in the 1880s and 1890s and the Positivist opposition to empire and that, furthermore, Hobson was seeking to define a new socialist imperialism.

One of the many strengths of the study is Claeys's sensitivity to the nuances and changes in thinking, and he is always careful not to impose a false symmetry on his interlocutors: H. M. Hyndman initially supported empire before becoming one of its most outspoken opponents, and Robert Blatchford harnessed socialist principles to an unapologetic jingoism. Claeys also perceptively traces the changes in nuance and argument in Hobson's thinking about empire. The book focuses on ideas and texts about empire more than the actual conduct of empire, although Claeys emphasizes two events in particular—the occupation of Egypt in 1882 and the Boer War—as key moments in the chronology of anti-imperialism. The degree to which socialist critiques of empire were taken up more broadly by the British public is not explored as fully as the intellectual trajectories of opposition to empire, although Claeys is attentive to an impressive variety of thinkers and commentators, both well known and more obscure, who were active as writers, polemicists, and reformers.

Although careful evidence is marshalled to support his arguments about the resilience and importance of Positivism, the Positivist elements in socialist views of empire and in Hobson's thinking in particular tends to put into the shadow other important sources of the idea of a socialist commonwealth: ethical socialism, British idealism (notwithstanding Hobson's opposition to Bosanquet's theory of the state), and the evolutionary social organicism that was so pervasive in the 1880s and 1890s. All these Claeys acknowledges, and yet he sees Positivism as having a conclusive and long-lasting impact. For example, the concern that empire could corrupt and imperil Britain did not originate with the Positivists and need not be evidence of a Positivist influence first and foremost, although Claeys demonstrates that Positivists infused this objection into their critique of empire. At times Claeys follows the critique of imperialism to the colonies; he, for example, highlights the forceful attacks on Indian finance in the 1860s by several Anglo-Indians in imperial government who were influenced by Comte. James Geddes and Sir Henry Cotton launched scathing critiques that ran parallel to Dadabhai Naoroji's later well-known analysis. More analysis of the transnational interchange of ideas that shaped anti-imperialism in Britain would have strengthened the study.

The book explores a variety of fascinating subthemes: lively disputes over the sovereignty of the state, contestations over the possibilities and limitations of religions fostering a tolerant cosmopolitanism, and the development of internationalism. This is a compelling study that revises the chronology of antagonism to empire and advances novel arguments about the legacy of Positivism and the religious sources and the communitarian ideals at the heart of anti-imperialism at the height of empire.