If there is a single conclusion to be reached from the historical literature on cybernetics that has emerged during the past several decades, it is that the men and women who embraced this new enterprise as a path to scientific unity were themselves anything but unified. Cybernetics, an almost mystical combination of mathematics, control technologies and engineering metaphors, was presented as a coherent set of ideas that might unify the physical, biological and social sciences. However, upon closer inspection, cybernetics appears to have meant different things to different people. Nowhere is this lack of unity clearer than in the life of Warren McCulloch, who, perhaps even more than Norbert Wiener, was cybernetics’ chief evangelist and sage. While McCulloch cast a retrospective coherence on his life in science as one driven by the mind–body problem, a closer look reveals a more complex man who traversed a variety of scientific institutions and disciplines, and was more animated by the possibility of transcending (rather than integrating) those disciplines, than by a single philosophical project. As Tara Abraham shows in her elegant and insightful biography, McCulloch's ‘transdisciplinary life in science’ was itself fairly conventional, yet produced an ‘intellectual showman’ (p. 1) who was compelling because of his ability to perform a variety of scientific identities.

Over eight chapters, Abraham deftly examines McCulloch's intellectual evolution from a precocious student of philosophy and psychology in the 1920s, to a young psychiatrist and neurophysiologist working in the prestigious laboratories of Columbia and Yale in the 1930s and 1940s, to an experimental electrical engineer at MIT's Research Laboratory of Electronics in the 1950s and 1960s. In contrast to his later self-presentation as a ‘rebel genius’, much of McCulloch's scientific life was utterly in line with the intellectual trends of the day. As a student, McCulloch was deeply influenced by the philosopher F.S.C. Northrop and the psychiatrist Eilhard von Domarus, who in different ways led McCulloch to his later career in psychiatry and neurophysiology. From these men, McCulloch developed two beliefs: first, that mental illness was largely the product of illogical thinking, and second, that neurophysiology offered a fruitful entry point into the philosophical and epistemological questions that puzzled him. While this might seem to support McCulloch's self-image as a man motivated by philosophical issues, Abraham shows that this also made him a perfect opponent for the Freudian psychoanalysis that was beginning to colonize American psychiatry, and an excellent candidate for support from the Rockefeller Foundation, which sought to support biologically oriented psychiatry. In these early chapters, Abraham paints a picture of McCulloch less as a ‘rebel genius’ than as a man who creatively recombined the intellectual trends of the post-war generation within an atmosphere in which the biological basis of mental disease was an ever-present preoccupation.

This preoccupation with mental illness and its biological roots led McCulloch both to the Illinois Neuropsychiatric Institute, his institutional home for the next decade, and to his collaboration with the mathematical wunderkind Walter Pitts. The pair's most enduring product, the 1943 paper ‘A logical calculus of the ideas immanent in nervous activity’, laid much of the groundwork for the modern concept of the neural network, as well as artificial intelligence and cognitive psychology. Yet despite its seeming modernity, Abraham demonstrates how the Pitts–McCulloch theory was itself the product of earlier practices of pre-war neurophysiology, and her deft handling of the somewhat obscure technical details of such practices as strychnine-based brain localization is impressive. At the same time, McCulloch began his association with the emerging cybernetics movement, and Abraham is at her strongest in her analysis of McCulloch's role as the intellectual ringleader of the Macy conferences. Abraham demonstrates both how important neurophysiology was for the emerging field of cybernetics (a point often lost in histories that have focused on Wiener), and how McCulloch's interdisciplinary rhetoric served as a cover for a more imperial aspiration to transcend the different biological and social sciences through the tools of mathematical modelling. Abraham's analysis of the early Macy meetings is perceptive, and she uses archival documents judiciously to demonstrate discord behind the scenes.

By the early 1950s, McCulloch had transitioned to a new institutional setting, the Research Laboratory of Electronics at MIT. This move enabled two additional reformulations of his scientific identity: first from neuropsychiatrist to engineer, and second from upstart scientific evangelist to the ‘rebel genius’ of the title, an enigmatic sage of the information age, remembered fondly by his students and collaborators for his egalitarian mentorship, his unkempt white beard, and his habit of subsisting for days on a diet of ice cream and whiskey. Yet beyond McCulloch's self-presentation lay a mode of theorizing in biology that was richly generative for the emerging fields of artificial intelligence and cognitive psychology. For McCulloch, mathematical theorizing was less a way of representing nature than a way of intervening in scientific practice – a legacy of his transdisciplinary life in science.

Rebel Genius, which grew out of Abraham's dissertation research on the history of mathematical biology, is an excellent example of the continued value of scholarly biography. Throughout, she uses the theoretical contributions of such scholars as Mario Biagioli and Judith Butler to keep an eye on McCulloch's self-fashioning of his scientific identity. These ideas are used with a light touch, and indeed, as a reader, I often wondered whether their invocation was entirely necessary; Abraham's presentation of McCulloch seemed compelling enough on its own. By contrast, her fine-grained look at the rhetoric and reality of interdisciplinarity should make her book a model for those interested in the explosion of hybrid scientific fields in the post-war world. Moreover, at a breezy 189 pages of text, Rebel Genius is an exemplar of concise scholarly prose. It should receive a wide readership, from those interested not only in the history of cybernetics, but also in twentieth-century science, interdisciplinarity and the brain and mind sciences more generally.