During the 1940s and 1950s, the Australian microbiologist F. Macfarlane Burnet sought a biologically plausible explanation of antibody production. In this essay, we seek to recover the conceptual pathways that Burnet followed in his immunological theorizing. In so doing, we emphasize the influence of speculations on individuality, especially those of philosopher Alfred North Whitehead; the impact of cybernetics and information theory; and the contributions of clinical research into autoimmune disease that took place in Melbourne. We point to the influence of local experimental and intellectual currents on Burnet s work. Accordingly, this essay describes an arc distinct from most other tracings of Burnet s conceptual development, which focus on his early bacteriophage research, his fascination with the work of Julian Huxley and other biologists in the 1920s, and his interest in North Atlantic experimental investigations in the life sciences. No doubt these too were potent influences, but they seem insufficient to explain, for example, Burnet s sudden enthusiasm in the 1940s for immunological definitions of self and not-self. We want to demonstrate here how Burnet s deep involvement in philosophical biology - along with attention to local clinical research - provided him with additional theoretic tools and conceptual equipment, with which to explain immune function.