Not Sufficiently Reassuring

Peter Godfrey-Smith

  • Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False by Thomas Nagel
    Oxford, 130 pp, £15.99, November 2012, ISBN 978 0 19 991975 8

The universe has woken up. If the scientific picture we currently have is right, this was an accident, roughly speaking, and also something that happened very locally. At various places some highly organised physical systems – living organisms – have become aware of the world they are part of. In a few cases they have also become aware of their awareness. These living systems are products of evolution by natural selection, an undirected process that began in a fortuitous combining of chemical and physical conditions, whose course is dependent on accidents of history, and which is driven by the slight reproductive advantages some organisms enjoy over others. Even if Earth is not the only place where this has happened, the vast majority of the universe contains no awareness, no life, no reasoning. We, the awoken parts of the universe, can look around and reflect on all this, including the fact that there is no overall purpose to our being here. So the universe has ‘woken up’, but in a local, accidental and low-key sense.

Thomas Nagel’s Mind and Cosmos rejects this view and tries to build another. His subtitle is ‘Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False’. It is false, Nagel says, because it cannot deal with a cluster of real phenomena: consciousness, the origin and evolution of life itself, our powers of reason, and our sense of the reality of moral values. In the place of materialism Nagel does not endorse a theological view, and he does not postulate souls as spiritual additions to the physical world. He aims instead for a unified picture, in which life, consciousness, reason and value are not inexplicable anomalies, but features of the world that arise naturally and fall into place as expected. The result is a view that embraces evolution but also has, as Nagel says, an ‘idealist’ character. Teleological principles may have moved the universe towards some kind of goal or fulfilment, and a glimmer of mentality may permeate even basic physical processes. For Nagel it is true in a more global way, a wholesale way, that ‘each of our lives is a part of the lengthy process of the universe gradually waking up and becoming aware of itself.’

Nagel begins with the clearest of materialism’s problems: the great difficulty it has explaining the subjective character of experience, the feel of our mental lives: the feel of seeing colours and tasting wine, the feel of thought itself. Despite all the careful work that has been done in this area over the past fifty years, for Nagel the problem is as recalcitrant as ever. Materialism does indeed struggle to give a good explanation of these features of our minds. However, if materialism were somehow true, it would seem not to be true. The view from inside a conscious physical system would be distinctive in ways that would make it hard to understand from a third-person perspective: having an experience is very different from describing that experience, regardless of what the system having the experience is made of.

This holds back some arguments against materialism, but problems remain. In response to them, Nagel outlines a form of ‘neutral monism’. Neutral monism has for some time been a fringe character in debates about the mind-body problem. It was developed in different forms by eminent figures in early 20th-century philosophy, including Russell and Dewey, but then faded. A neutral monist argues that the mental and the physical are both manifestations of something more basic. It is a mistake, according to this view, to try to explain mind in terms of matter, or vice versa (hence the term ‘neutral’). But it is also a mistake to think there are two fundamental ingredients of the world (as a dualist does), rather than one.

The unpopularity of the view notwithstanding, Nagel is right that neutral monism is the best alternative to materialism. He thinks we have a clear idea of what the mental and physical are, that we can see neither can be reduced to the other, and that the only way to make sense of the situation is to say that all of nature, at bottom, contains a bit of both. A different and to my mind more promising version of the view has a more critical flavour. It holds that standard ways of thinking about the mind-body problem are dependent on crude conceptions of both the mental and the physical. We think we have a clear and definite idea of what a ‘purely physical’ or ‘purely mental’ process is like, but our grasp of both is so poor that we do a bad job of thinking about how they might be related, and see a gulf that isn’t really there. Nature gives rise to what appear to us as ‘physical’ processes and ‘mental’ processes, but both arise from something that fits into neither of these crude categories. Nagel’s neutral monism, however, is more of the ‘glue the two together’ variety than this second, critical strain. He thinks we can see, even in advance of changes that may take place in physics, that ‘something must be added to the physical conception of the natural order.’

Nagel then argues that the puzzle about minds and bodies is ‘not just a local problem’ but one that seeps out and affects everything else. If evolution is able to give rise to conscious beings that are not merely physical systems, then evolution is not the purely physical process it is usually taken to be. He allies this thought with a sceptical treatment of mainstream evolutionary biology itself, in its handling of both the origin of life and its subsequent history.

We still know very little about how life began, and it is hard to assess whether this problem will eventually yield to ‘normal science’ or whether a more dramatic innovation is needed. The subsequent course of evolution, once life was underway and took the form of cells and organisms, is another matter. We know a good deal about that. Nagel, in what is the weakest part of his book, asks whether ‘in the available geological time’ since life began, it is likely that ‘a sequence of viable genetic mutations should have occurred that was sufficient’ for the evolution of complex organisms to have taken place. This is expressed not as a personal musing, but as a ‘problem of probability’ for the mainstream view. If the time available is not enough, how much more is needed? As Nagel’s talk of ‘problems of probability’ indicates, this is a quantitative question. The earth is about 4.5 billion years old, according to mainstream estimates, and life has been present for perhaps 3.5 billion of those years. If geologists determined tomorrow that they had underestimated the time available by (say) two billion, would that make the difference? Nagel doesn’t say a word about how much time is missing or how serious the problems of probability might be.

This area is one in which intuitions are worth nothing, though that has rarely deterred the sceptics. In the decades after On the Origin of Species appeared it was common to say that small reproductive advantages, of the kind posited by Darwin, could never produce large-scale change. It was common to say this, at least, until people looked explicitly at the mathematics of the problem. In his beautiful book Mimicry in Butterflies (1915), Reginald Punnett published a table of calculations by his colleague H.T. Norton showing that a gene associated with a reproductive advantage of 1 per cent, for example, could become established in a population in about a thousand generations. This was the first of many models showing the surprising power of slight advantages in evolution. Some, such as Norton’s, assume that an adaptive mutation has arisen and look at what happens next. Another kind of model assesses the likelihood that a series of minor and biologically plausible mutations will produce a complex new trait from a simpler state. The development of the eye has been a favourite test case ever since Darwin. In 1994 Dan-Eric Nilsson and Susanne Pelger looked at how long evolution by natural selection would take to transform a smooth, light-sensitive skin surface to a focusing camera eye. Their ‘pessimistic estimate’ was surprisingly short: a few hundred thousand years. The individual steps involved in their model are not implausible engineering leaps but small changes to the density, folding and chemistry of living structures. Nagel respects the ‘intelligent design’ movement for its refusal to be browbeaten by scientific orthodoxy, but echoing its ill-founded claims about shortages of time and the limited power of ‘chemical accident’ doesn’t assist his project at all.

For Nagel, evolutionary explanations of the standard kind have particular problems when applied to the human faculties of consciousness, reason and moral judgment. First, he says, a good explanation will not imply that these things came about completely by accident: ‘The likelihood must have been latent in the nature of things.’ Second, a good account of where our powers came from must be consistent with our sense of the reliability of our reasoning faculties. Darwinism, Nagel believes, fails on both counts.

I will focus on the second of these. Nagel argues that if the standard evolutionary account is true, we have no grounds to trust the reliability of our own powers of reasoning: our best science would cast into doubt the idea that we can be rational enough to have good science. It makes sense, for Nagel, that evolution would have produced organisms who can track the world with perception, learn, and attend to their biological needs. But human thought reaches beyond topics with any practical relevance in the environments in which we evolved. Our minds extend into higher mathematics, physics and moral reasoning, and the standard evolutionary view gives us no reason to think that anything we do there might be reliable. Even if we were able to tell a causal story, to trace the history through which we came to be able to think about these impractical things, that could not be enough. ‘Any evolutionary account of the place of reason presupposes reason’s validity and cannot confirm it without circularity.’

The central problem here concerns Nagel’s view of what any evolutionary story could reasonably contribute. Nagel does not merely ask for an explanation of how our powers of reasoning come to exist, and how they came to work as well as they do, but also asks that the evolutionary story give us ‘grounds for trusting’ them. This is a demand, though, that no evolutionary account needs to meet. Suppose I had good reason to think that evolution had honed me to be a fine reasoner. That would be good news, but it is a fact about the past, and about an inherently noisy process. If I want to work out whether I have good grounds for trusting my reasoning now, looking back that far in time could give me only weak support, and it would make more sense to try to assess my skills more directly. Any information about what we are supposed to be able to do is secondary to information about what we can actually do. Mathematics, for example, is a surprising product of our minds, but when we build bridges using it, do the bridges stay up or fall down? We might be misled in some of these attempts to assess our own thinking – just as we might make mistakes in attempts to reconstruct our history. It would be puzzling if evolutionary theory said it was impossible for us to have reliable reasoning skills, in part because that reasoning itself would be thrown into doubt. But that is not our situation. With respect to our present-day reliability as reasoners, evolutionary biology isn’t very informative either way. Current views about the evolution of human cognition are compatible with our having evolved reasoning skills that are highly reliable in novel contexts – compatible, too, with our having evolved reasoning skills that are not.

Consider reading and writing. It is not greatly surprising that evolved organisms of the kind we are might, having developed language, later start to write things down. This did not happen through the spread of genetic mutations, and literacy is only loosely coupled to biological evolution. Literacy is an add-on, from a biological point of view, but once it is present, the possibilities unlocked are endless.

How much difference would the truth of Nagel’s preferred view of the universe make to this question about trust in human reason? Suppose a strongly teleological-idealist view is true, and evolution has been steadily wending its way towards the production of systems with reliable reasoning powers. This would be some comfort, but for anyone wondering whether to trust the reasoning they are doing in the present, it remains true that much has happened, and much could have gone wrong, along the way. There is no substitute for trying to work out how well we are actually doing, whether or not we think the universe wants us to do well. This would not be so if you believed (as Descartes did) that the processes responsible for your existence were guaranteed to give you reliable powers of thought in certain domains. But Nagel’s view, secular and evolutionary, is not intended to have the idealist octane that could deliver such a guarantee. When we assume anything less than that, we are left, as before, using more direct and mundane ways to assess our powers, seeing which of our bridges stay up and which ones fall down.

In an early chapter Nagel summarises his view by saying that naturalism does not give a ‘sufficiently reassuring’ account of our rational capacities. At first I wondered whether he was using this phrase with tongue in cheek, but it appears not. So the question arises: sufficiently reassuring for what? Reassuring enough for us to feel OK, or reassuring enough to be true? There is a big difference. Nagel’s book is driven by a demand for intelligibility and reassurance, an insistence on them. A comparison can be made with William James, writing about these matters a little over a hundred years ago in his book Pragmatism. For James, who embraced Darwinism, the problem was not materialism’s past, but its future. Physics foretold a future in which all life would eventually die out and all traces of human activity would disappear: ‘Dead and gone are they, gone utterly from the very sphere and room of being. Without an echo; without a memory … This utter final wreck and tragedy is of the essence of scientific materialism as at present understood.’ James hoped for something more, including a different ending to the cosmic story. For his inchoate hoping and his defence of the right to keep hold of such hopes, James is roundly criticised and sometimes ridiculed. James hoped where Nagel insists, but insistence here is hollow.

Nagel may reply that the ground for insistence as opposed to hope, his foot in the door, is again the mind-body problem: a central theme of his book is that the perplexities of mind and body seep out and affect other things. They do, but not in a reassuring direction. There is nothing in the sheer strangeness of the mind-body problem that points towards a view vindicating confidence in our powers, or the idea that evolution was somehow pulled towards producing us.

I have been critical, but I admire parts of Nagel’s project. I agree with him that one task of philosophy is to explore unorthodox views of the world, even when they can only be sketched and even when they bump awkwardly against the science of the day. While Nagel spends some time in this exploratory mode, however, and sometimes says that there is much we do not know, the overall strategy of the book is to insist that there are many things we do know: that reason has a ‘transcendent’ quality, that moral values are objectively real and that any account of human powers must accommodate ‘the confidence we feel’. This is reflected also in the way Nagel puts the case for neutral monism, not by arguing that we have been thinking too crudely about the opposition between mental and physical, but by insisting that we can see, right now, that the physical sciences and a biology drawing on them will never provide the resources needed to explain consciousness. The cover of Mind and Cosmos declares that the materialist Neo-Darwinian view is ‘almost certainly false’. While the mind-body problem continues to pose challenges for materialism, the collection of phenomena Nagel discusses do not hang together in the way he says. A Darwinian account of our origins brings with it little reassurance, but that isn’t a reason to doubt its truth. It doesn’t give us grounds for confidence in our powers of reasoning, but neither does it undermine that confidence. Darwinism offers a view according to which the evolution of awareness and reason is, in a broad sense, accidental. Some will respond by hoping for more, for a universe in which we are supposed to be here. Others might find that our deep contingency brings with it a peculiar sense of freedom.