Cooperative Division of Cognitive Labour: The Social Epistemology of Photosynthesis Research

How do scientists generate knowledge in groups, and how have they done so in the past? How do epistemically motivated social interactions influence or even drive this process? These questions speak to core interests of both history and philosophy of science. Idealised models and formal arguments have been suggested to illuminate the social epistemology of science, but their conclusions are not directly applicable to scientific practice. This paper uses one of these models as a lens and historiographical tool in the examination of actual scientific collectives. It centres on the analysis of two episodes from the history of photosynthesis research of the late nineteenth- to mid-twentieth centuries, which display a wide and coordinated intellectual diversity similar to Kitcher’s “division of cognitive labour” (1990). The concept, I argue, captures important aspects of the photosynthesis research communities, but the underlying process unfolded in ways that differ from the model’s assumption in interesting ways. The paper unravels how the self-organised interplay of cooperation and competition, and the dynamics of individual and collective goals within scientific communities were influential factors in the generation of knowledge. From there, some thoughts are developed on how historical and philosophical approaches in the analysis of science can productively interact.

Chlorophyll and photosynthesis

Photosynthesis is the prerequisite of all life on earth. Chlorophyll fulfils the requirements for photosynthesis: the absorption of visible light, the photochemical capabilities, a rich supply of redox levels and chemical stability. The biosynthetic pathway of chlorophyll can be read as the evolutionary history of photosynthesis. Our exegesis is that the primary porphyrins served for early photosynthesis. The porphyrins readily photo-oxidize organic compounds under the reducing, aqueous conditions of this early era. The formation of oxidized substances in a reducing atmosphere supplied the thermodynamic gradient necessary for organized life processes. Conversely, the closed-shell metalloporphyrins, notable magnesium porphyrins, are powerful photoreducing agents. When coupled to the ultimate electron source, water, oxygen was produced and the modern era of photosynthesis was born. At the same time, the efficiency and usefulness of the photopigments was increased by incorporating them into the organized cellular system of membranes. The clear gradient of ionic to hydrophophic structures along the biosynthetic pathway from porphyrins to chlorophyll supports this view. Experimental evidence on the photochemistry of porphyrins pigments in solution and in lipid bilayers form the basis for these arguments. In this way we can relate the structure of chlorophyll to its function in photosynthesis.