This is an excellent book: smart, elegantly written, well researched and ambitious in scope. Linstrum aims to tell the story of psychology within the British Empire from the start of the twentieth century to the era of decolonization. His six chapters offer a set of well-crafted, richly evidenced case studies. The contents page suggests a book of three parts, with sections on minds, testing and experts. In fact, these three themes intersect across the book as a whole. The chapters are also so arranged as to unravel a story of development across time. The opening chapter deals with probably the most familiar territory in the book, the famous Torres Strait expedition in which a group of remarkable Cambridge anthropologists effectively took the laboratory out to the field and as result began to rethink evolutionary assumptions about difference between the civilized and the primitive. The second chapter takes this story forward with a particular focus on the way that Freudian ideas and an interest in dreams were projected onto the study of Britain's imperial subjects in the interwar years. The next two chapters turn the focus towards mental testing. Linstrum casts this movement in fresh light, bringing out a meritocratic impulse which tended to eclipse its potential as a tool to reify ideas of racial hierarchy. Initially, the main focus of effort was education, in the Second World War it turned to aptitude testing in the armed forces, and then after the war it turned to the workplace. The rich detail enables Linstrum to demonstrate the tensions and compromises in translating the vision to a less impressive reality as testing often ended up being more about increasing efficiency and productivity than about fairness and opportunity. The penultimate chapter turns to the use of psychology in post-war counterinsurgency and a broader struggle for hearts and minds. Here, and in the final chapter, which deals with the British contribution to post-war international health and welfare organizations, we find British psychological influence fading and being surpassed by American social science. In the post-independence era it became convenient to portray the Americans as the social-scientific modernizers, the British imperialists as having been tied to classical notions of character. One of the central achievements of Linstrum's book is to show that such a stark model of British backwardness is no longer sustainable.

Linstrum concludes that the imperial project of ruling minds was too big to succeed, but also too big to fail; a tale of continuity, but also of change over time; of colonial power, but also of anti-colonial critique. His account, in other words, resists simplistic generalization. Nevertheless, he does also show quite clearly that a body of work that presents imperial psychology as simply a tool of control and domination is misleading. Ruling Minds clearly reveals rule to have been a messy and negotiated process, and the rulers and their experts to have sometimes used the tools of psychology to break down racial boundaries, make rule fairer, and even challenge rule itself. Also hinted at but less fully developed is a history of how psychology might provide a tool for the colonized themselves. The picture that emerges may be a little too generous towards imperial psychology for the tastes of those who have studied the sometimes harsh consequences of policy in practice in particular imperial contexts, but Linstrum's focus is on the broader intellectual climate, rather than effects, and here his nuanced analysis is fresh, thought-provoking, and largely persuasive. Where it would be useful to hear more is in relation to questions of underlying structure, system and scale. For instance, there is the issue of disciplinary and professional formation. Here, Linstrum is somewhat loose in the handling of his central focus of analysis. Most often it is psychology, but elsewhere it is some less precise formulation such as mind science, at points it turns towards a broader frame of human science, and for much of the book the key actors are anthropologists rather than psychologists. There is good justification for this. As Linstrum notes, psychology was a discipline in the process of formation at the start of the period, and his analysis is excellent at demonstrating the prevalence and significance of psychological thinking well beyond the discipline and profession. Yet something is also lost in this approach. By the end of the period, disciplinary lines and professional interests had been more clearly drawn, and we might hear more about the resulting politics. Likewise, Linstrum notes at several points the importance of ‘networks of empire’ for a history such as this, and he does draw our attention to some key partners in such a network, including government bodies and large commercial companies. But the picture of the system (and also its scale), and thus of the politics of knowledge, remains somewhat impressionistic. We see its complexity and myriad partners, and we are alerted to some of the channels of communication, but we emerge in the end without a definitive picture of the map of power, the place of disciplines and professions within this, and the changing structure and dynamics of this system over time. This is, of course, a lot to ask for, and it would be unfair to expect this of a book that does so much in opening up the subject, but these are perhaps questions of the sort raised for future scholarship by Linstrum's fascinating and valuable study.