(p.253) A.6 The Death of Emergentism
(p.253) A.6 The Death of Emergentism
McLaughlin explains how British Emergentism continued to flourish well into the twentieth century. This highlights the question at issue in this Appendix. Given that thinkers continued to posit special mental and vital forces until well after the Great War, why has the idea of such forces now finally fallen into general disfavour?
Here I think we need to refer to a second line of argument against such forces, an argument from direct physiological evidence. We can view this second argument as operating against the background provided by the earlier argument from fundamental forces. The earlier argument suggested that most natural phenomena, if not all, can be explained by a few fundamental physical forces. This focused the issue of what kind of evidence would demonstrate the existence of extra mental or vital forces. For once we know which other forces exist, then we will know which anomalous accelerations would indicate the presence of special mental or vital forces. Against this background, the argument from physiology is then simply that detailed modern research has failed to uncover any such anomalous physical processes.
As I intimated above, the relevant research dates mostly from the twentieth century. Physiological research in the nineteenth century did not penetrate to the level of forces operating inside bodies. However, in the first half of the twentieth century, the situation changed, and by the 1950s it had become difficult, even for those who were not moved by the abstract reductionist argument from fundamental forces, to continue to uphold special vital or mental forces. A great deal became known about biochemical and neurophysiological processes, especially at the level of the cell, and none of it gave any evidence for the existence of special forces not found elsewhere in nature.
During the first half of the century the catalytic role and protein constitution of enzymes were recognized, basic biochemical cycles were identified, and the structure of proteins analysed, culminating in the discovery of DNA. In the same period, neurophysiological research mapped the body's neuronal network and analysed the electrical mechanisms responsible for neuronal activity. Together, these developments made it difficult to go on maintaining that special forces operate inside living (p.254) bodies. If there were such forces, they could be expected to display some manifestation of their presence. But detailed physiological investigation failed to uncover evidence of anything except familiar physical forces.
In this way, the argument from physiology can be viewed as clinching the case for the completeness of physics against the background provided by the argument from fundamental forces. One virtue of this explanation in terms of these two interrelated arguments is that it yields a natural explanation for the slow advance of the completeness of physics through the century from the 1850s to the 1950s. Imagine a ranking of different thinkers through this period, in terms of the amount of physiological evidence needed to persuade them of completeness, in addition to the abstract argument from fundamental forces. Helmholtz and his colleagues would be at one extreme, in deciding for completeness on the basis of the abstract argument alone, without any physiological evidence. In the middle would be those thinkers who waited for a while, but converted once initial physiological research in the first decades of the twentieth century gave no indication of any forces beyond fundamental forces found throughout nature. At the other end would be those who needed a great deal of negative physiological evidence before giving up on special forces. The existence of this spectrum would thus explain why there was a gradual buildup of support for the completeness of physics as the physiological evidence accumulated, culminating, I would contend, in a general scientific consensus by the 1950s.
Brian McLaughlin offers a rather different explanation for the demise of British Emergentism. He attributes it to the 1920s quantum‐mechanical reduction of chemical forces to general physical forces acting on subatomic components (1992: 89). But it seems unlikely that this could have been decisive. After all, why should anybody who was still attracted to sui generis animate forces in the 1920s have turned against them simply because of the reduction of chemistry to physics? Why should it have mattered to them exactly how many independent forces there were at the level of atoms? At most, the reduction of chemistry to physics would have added some marginal weight to the argument from fundamental forces, by showing that yet another special force reduces to more basic forces. But anybody who had resisted the argument from fundamental forces so far, still upholding vital and mental forces as extra members of the pantheon of fundamental forces into the twentieth century, would surely not be bowled over simply because the physical theorists had now modified the precise inventory of forces operating at the atomic level. To understand why British Emergentism lost ground over the first half of the twentieth century, (p.255) we need to recognize a different kind of argument: namely, the argument from the emerging findings of physiological research.15
(15) I have presented the conservation of energy as a boundary principle which limits the range of possible forces and helped rule out special animate forces. Barry Loewer has pressed me on whether this emphasis on the conservation of energy is consistent with modern quantum mechanics. Let me make two brief comments. (1) On some interpretations, quantum systems do not always respect the conservation of energy. While energy is conserved in the ‘Schrödinger evolution’ of quantum systems, it is apparently violated by ‘wave collapses’. Some, including myself, take this to argue against wave collapses. But, even if you don't go this way, the conservation of energy will still be respected in Schrödinger evolutions, and this will itself limit the range of (non‐collapse‐causing) forces. (2) On some, but not all, collapse interpretations, distinctive special causes will be responsible for whether a collapse occurs or not (even though the subsequent chances of the various possible outcomes will still depend entirely on prior physical forces). I am thinking here of interpretations which say that collapses occur when physical systems interact with consciousness (or indeed which say that collapses occur when there are ‘measurements’, or ‘macroscopic interactions’, and then refuse to offer any physical explanations of these terms). On these interpretations, the completeness of physics will be violated, as well as the conservation of energy, since collapses don't follow from more basic physical laws, but depend on ‘emergent’ causes. It would seem an odd victory for anti‐materialists, however, if the sole locus of sui generis mental action were quantum wave collapses.