Philosophy of Biology and Cognitive Sciences

In biology, the stochastic variation of gene expression that results from low numbers of molecules, thermal agitation, and quantum effects is generally described as noise (Kærn 2005; Pipel 2011). Within these processes, noise is historically conceived by biologists as mere nuisance (Heams 2014). Indeed, in the mid-twenty century some internal stochastic instability was supposed to affect the normal course of intracellular processes, thus producing stochastic variability in cell phenotype even in the absence of any genetic and environmental change. Starting from the 1990s, this hypothesis has been established thanks to theoretical and experimental investigations: cell-to-cell non-genetic variability is due to stochastic fluctuations during the process of gene expression, what has started to be called “noise” (McAdam & Arkin 1997). For example, cell-to-cell phenotypic variability among isogenic cells is thus considered as simply an error, a random deviation with respect to what is expected when one knows their genotype and the environment they grow in. In other words, chance is conceived in this context as a mere nuisance to the regular, deterministic, and predictable progress of molecular processes taking place inside cells, in particular gene expression. Recently however, noise has been recognized as having a positive function (McAdam & Arkin 1997; Elowitz 2002; Eldar and Elowitz 2010). Nevertheless, the epistemological status of noise remains fuzzy: despite some biologists recognizing its functionality, there is no consensus around what exactly it explains. In the presentation, we argue that stochasticity affecting various biological processes involved in cell functioning may actually play a positive, constructive role, contributing to the explanation of these processes, and should thus be conceived as more than just noise. More specifically, our objective is dual. First, we aim at showing that the way noise is currently conceived in the biological literature is ambiguous because it mixes up ontological and epistemological considerations. Second, we argue for a positive conception of chance, which is intended to enrich and augment the current, mostly negative, epistemology of chance that has characterized the biological discourse about molecular and cellular processes since the 1970s. According to the augmented epistemology we argue for, chance can be conceived as a “theoretical operator” (Morizot 2012) with a biological, and even functional, relevance. When it is shown to play a role in the functioning of the cell as well as in the development of individual organisms throughout time, chance can be conceived as a behavior of cellular processes, and has to be taken into account in models and explanations as such.