On the meaning of chance in biology

Chance has somewhat different meanings in different contexts, and can be taken to be either ontological (as in quantum indeterminacy) or epistemological (as in stochastic uncertainty). Here I argue that, whether or not it stems from physical indeterminacy, chance is a fundamental biological reality that is meaningless outside the context of knowledge. To say that something happened by chance means that it did not happen by design. This of course is a cornerstone of Darwin's theory of evolution: random undirected variation is the creative wellspring upon which natural selection acts to sculpt the functional form (and hence apparent design) of organisms. In his essay Chance & Necessity, Jacques Monod argued that an intellectually honest commitment to objectivity requires that we accord chance a central role in an otherwise mechanistic biology, and suggested that doing so may well place the origin of life outside the realm of scientific tractability. While that may be true, ongoing research on the origin of life problem suggests that abiogenesis may have been possible, and perhaps even probable, under the conditions that existed on primordial earth. Following others, I argue that the world should be viewed as causally open, i.e. primordially indeterminate or vague. Accordingly, chance ought to be the default scientific explanation for origination, a universal 'null hypothesis' to be assumed until disproven. In this framework, creation of anything new manifests freedom (allowing for chance), and causation manifests constraint, the developmental emergence of which establishes the space of possibilities that may by chance be realized.