This article examines the intellectual and institutional factors that contributed to the col- laboration of neuropsychiatrist Warren McCulloch and mathematician Walter Pitts on the logic of neural networks, which culminated in their 1943 publication, “A Logical Calculus of the Ideas Immanent in Nervous Activity.” Historians and scientists alike often refer to the McCulloch–Pitts paper as a landmark event in the history of cybernetics, and fundamental to the development of cognitive science and artificial intelligence. This article seeks to bring some historical context to the McCulloch–Pitts collaboration itself, namely, their intellectual and scientific orientations and backgrounds, the key concepts that contributed to their paper, and the institutional context in which their collaboration was made. Al- though they were almost a generation apart and had dissimilar scientific backgrounds, McCulloch and Pitts had similar intellectual concerns, simultaneously motivated by issues in philosophy, neurology, and mathematics. This article demonstrates how these issues converged and found resonance in their model of neural networks. By examining the intellectual backgrounds of McCulloch and Pitts as individuals, it will be shown that besides being an important event in the history of cybernetics proper, the McCulloch– Pitts collaboration was an important result of early twentieth-century efforts to apply mathematics to neurological phenomena.

Recently, historians have focused on Warren S. McCul¬loch’s role in the cybernetics movement during the 1940s and 1950s, and his contributions to the develop¬ment of computer science and communication theory. What has received less attention is McCulloch’s early work in neurophysiology, and its relationship to his philosophical quest for an ‘experimental epistemology’ – a physiological theory of knowledge. McCulloch’s early laboratory work during the 1930s addressed the problem of cerebral localization: localizing aspects of behaviour in the cerebral cortex of the brain. Most of this research was done with the Dutch neurophysiolo¬gist J. G. Dusser de Barenne at Yale University. The con¬nection between McCulloch’s philosophical interests and his experimental work can be expressed as a search for a physiological a priori, an integrated mechanism of sensation.

Much scholarship in the history of cybernetics has focused on the far-reaching cultural dimensions of the movement. What has garnered less attention are efforts by cyberneticians such as Warren McCulloch and Norbert Wiener to transform scientific practice in an array of disciplines in the biomedical sciences, and the complex ways these efforts were received by members of traditional disciplines. In a quest for scientific unity that had a decidedly imperialistic flavour, cyberneticians sought to apply practices common in the exact sciences – mainly theoretical modeling – to problems in disciplines that were traditionally defined by highly empirical practices, such as neurophysiology and neuroanatomy. Their efforts were met with mixed, often critical responses. This paper attempts to make sense of such dynamics by exploring the notion of a scientific style and its usefulness in accounting for the contrasts in scientific practice in brain research and in cybernetics during the 1940s. Focusing on two key institutional contexts of brain research and the role of the Rockefeller and Macy Foundations in directing brain research and cybernetics, the paper argues that the conflicts between these fields were not simply about experiment vs. theory but turned more closely on the questions that defined each area and the language used to elaborate answers.

Key words: Cybernetics, Macy foundation, Neurophysiology, Rockefeller Foundation, Theoretical modeling, Warren S. McCulloch