Mind-Brain Lecture: Russell Powell (Boston)
Stephen Jay Gould famously argued that replaying the ‘tape of life’ would result in radically different evolutionary outcomes. Recently, biologists and philosophers of science have paid increasing attention to the theoretical importance of convergent evolution—the independent origination of similar biological forms and functions—which many interpret as evidence against Gould’s thesis. In this paper, I examine the relevance of convergent evolution for the radical contingency debate. After clarifying the key questions, concepts, and epistemic problems at stake, I go on to show that under the right conditions, episodes of convergent evolution can indeed constitute natural experiments that support inferences regarding the deep counterfactual stability of macroevolutionary outcomes. The problem, however, is that proponents of convergence have lumped causally heterogeneous convergent phenomena into a single evidentiary basket, presenting the total body of convergence data as a refutation of Gould’s thesis. In so doing, they have misinterpreted the radical contingency thesis and failed to engage with its core claims. Adopting a more nuanced approach to convergent evolution allows us to differentiate iterated evolutionary outcomes that are plausibly common among alternative evolutionary histories and subject to law-like generalizations, from those that do little to undermine, and may even support, the Gouldian view of life. I then apply this framework to one particularly provocative implication of Gould’s thesis, namely the notion that the evolution of mind is radically contingent. I conclude that whereas there is little to indicate the evolutionary robustness of specific animal body plans, patterns of convergent evolution suggest, contra Gould, that mind is likely to be an important feature of any living world.
