Last April, Bryce Huebner and I had a Twitter exchange about emergence in biology. I felt that we were talking past each other and tried to work out how it had happened. I suspected that it was due to the way the concept of emergence had been used in different traditions, and I sketched the following tentative history. (I should stress that this is speculative; I’m not a historian.)
1. Late 19th – early 20th century: Some British philosophers (Broad, Lloyd Morgan, Alexander) started using ’emergentism’ to describe a metaphysical view on which the world is radically layered, with new fundamental properties and powers spontaneously appearing at each level, building up to the mental.
2. Mid 20th century: That kind of emergentism was empirically falsified, and philosophers rejected it. However, dualist philosophers continued to claim that some mental properties and powers are fundamental, emerge spontaneously, and exert a ‘top-down’ influence on the physical world, causing particles to behave in ways that physics alone could not predict.
3.Late 20th century: Scientists adopted the term ’emergence’, ignoring its metaphysical baggage and using it in a different sense to characterize global features of complex systems, especially self-sustaining ones. Confusingly, these scientists often spoke of these global features as exhibiting a ‘top-down’ causal influence — meaning that the components of complex systems are causally sensitive to global conditions, not that global features appear spontaneously and exert a fundamental causal influence on the physical world, additional to that of the components.
5. Late 20th – early 21st century: To capture the difference between the philosophical and scientific uses, philosophers drew a distinction between strong and weak emergence. However, they tended to define weak emergence in terms of deducibility and denial of ‘top-down’ influences, which made scientists think that that ‘weak’ emergentists denied the kind of global influences they needed to talk about.
6. Same time: Some dualist philosophers seized on this, claiming that scientists themselves were now talking of strong (spontaneous, fundamental) emergence. If strongly emergent features are common in the natural world, then why shouldn’t aspects of the mind be strongly emergent? Science vindicates dualism!
7. April 2021: Bryce and Keith talk past each other, Bryce adopting the scientific use, Keith the philosophical one.
At the time, Bryce and I talked of writing this up as a short paper, which we may still do. Meanwhile, if anyone has any comments, I’d be grateful for them. Comments from historians of science and philosophy would be particularly welcome!