Latour aims to develop a [speculative/pragmatic?] realism that “would offer the agents of the world a more interesting role than that of passive object.” Since realism largely perceives matter to be inert, passive, and indifferent (unrelated to human history), Latour wonders whether the great parable of this realism might be Louis Pasteur’s discovery of Lactic Acid. Previous chemists had perceived the fermentation to be attributed to some sort of disintegration, taking place in specific types of “fermentable matter.” Latour wishes to divert attention away from Pasteur, and to the lactic acid: “Pastuer as an event that occurs to lactic acid.” What is his method? A turn to Whitehead: “Pasteur’s laboratory appears to us an occasion offered to trajectories of entities that inherit preceding circumstances by deciding to persevere in a new way of being.”
How does Whitehead’s ontology explain the event? Rather than perceiving the network of scientific instruments, political bodies, cultural ethos, and scientific knowledge as naturally extending itself to manifest lactic acid (an ANT approach), Latour believes that there is an actual occasion, in which lactic fermentation is concresced through this network, but also through the agency of Pasteur, who betrays previous chemistry by attributing the process to the yeast. This has never happened before (and yet, this yeast has existed for millenia [an eternal object?]), and consequently will become datum since it is a creative, novel event. “Fermentation has experienced other lives before now (1857) and elsewhere, but its new concrescence is a unique, dated, localized life made up in part of Pasteur – himself transformed by his second great discovery – and in part of the laboratory. By speaking of events defined in terms of their relations, I am sketching here the history of Pasteur and his yest, of the yeast and its Pasteur.”
The dilemma, for Latour, has traditionally been between a realist epistemology that perceived Pasteur’s yeast as an event and a constructionist epistemology that sees the yeast after-the-fact as a substance (in order to satisfy the need for a theoretical presupposition). Pasteur himself sees no contradiction between these, indicating a unique ontology that Latour quotes:
The experimenter, a man of conquest over nature, finds himself ceaselessly at grips with facts that are not yet manifested and exist, for the most part, only potentially in natural law. The unknown in the possible and not in what has been – this is his domain (Latour’s italics)
In the annals of history, this yeast must be given its fair due, and Pasteur should be seen as an event happening to yeast and yeast as an event happening to Pasteur (and all of biology, chemistry, science, and human history). Nonhumans are an integral part of historicity…