Darwin’s pivotal role in biological sciences is now matched by a similar position in philosophy – his discoveries stand at the centre of attempts to understand ourselves and our world. Darwin showed us, once and for all, that we are natural creatures, continuous in most respects with other animals. He showed us that our emotional and cognitive repertoires are formed in the service of survival and reproduction in the specific environments in which we find ourselves. In this we are the cousins of apes, wolves, sparrows and squid alike. This means that if we are to understand human attributes like consciousness or reason, we must “naturalise” them, seeing them not as magical intrusions into the natural world but as intelligible results of the workings of that world, the upshot of millennia of small variations, comparative advantages, adaptations, and thence survival. This Darwinian lesson dominates all cognitive science, neurophysiology and philosophy equally.

Illustration by Gary NeillSo what role is there for specifically philosophical thought? Philosophy has always had two goals: to understand the nature or the world, and to understand the nature of ourselves as parts of it. Each goal has become fragmented and specialised with the progress of science. To understand the world we look to cosmology, physics and chemistry, while to understand ourselves we look to biology, neurophysiology and cognitive science. The role of the philosopher is no longer to lead those sciences, nor even, as John Locke thought, to act as an “honest under-labourer”, helping to clear the ground they are to cover, but more to try to interpret their results in human terms: that is, in terms of meaning, practice, ethics or politics.

The interpretive task does not disappear automatically with scientific progress. Scientists themselves are eager to explain what their results mean for human lives, and biologists have often led the charge. Yet all too often their explanations have more to do with ideology than with science. Consider, for example, the idea that an implication of Darwinism is that we are all selfish, or at any rate driven by selfish machinery within us. The philosopher insists on asking whether this is true, and whether in any event it is an implication of the theory of natural selection. There is excellent reason for supposing it is not true: we act on a very different variety of motives than the selfish hypothesis allows us. But then the biologist may be driven to suppose that this fortunate characteristic in turn must be explained by some kind of miraculous, unnatural capacity of human beings somehow to overcome their biological natures – thereby throwing himself into the arms of theologians and “dualists” bent on separating mind from matter.

Philosophers try to do better than this, and the first step is to point out that there are perfectly intelligible evolutionary scenarios in which the kinds of creature that are prepared to sacrifice something for the common good do better than kinds of creature that are not. If the environment is such that we must all hang together or we all hang separately, then we had better hang together. Human beings, with their weak individual abilities but immense social capacities, their long periods of infancy and longer periods of mutual dependence, are that kind of creature.

Seeing this involves no departure from Darwin, who himself wrote encouragingly and admiringly about the competitive advantage that moral, social, and even altruistic motivations would give to groups of people in whom they are found. It may be a departure from those biologists who thought it was unscientific to think in terms of groups and their competitive advantage, but this in turn was a piece of ideology rather than any kind of implication of scientific fact.

The selfish hypothesis illustrates the greatest danger in misapplying Darwin, which comes from neglecting the plasticity of our minds. The idea that our fate lies in our genes can strangle our thinking here, leading to fatalism, pessimism and a counsel of helplessness in the face of war, overpopulation and resource depletion. A valuable part of Darwin’s legacy is the understanding of variation within species and between species. Thinking of one “fixed” human nature, useless in the face of new challenges and forever cemented by our genetic inheritance is a misreading of evolution. Darwin tells us nothing about the relative importance of genetic inheritance versus cultural environment in forming the adult human being, any more than chemistry forces us to decide whether iron rusts because of its chemical constitution or because of the environment in which it is put.

There is nothing contrary to Darwin in noting that the children of a culture in which norms of cooperation are entrenched will be much more likely to grow into cooperative adults than children who start in a world of the war of all against all. Furthermore we must be clear that it is a political and social achievement to sustain such a culture. We cannot rely on our natures to do it for us, as the unhappy descents into bellicose equilibria of many parts of the world show.

Fortunately the life sciences are themselves in retreat from the genetic determinism that briefly seemed to piggyback on the triumphs of the unravelling of the gene. We now know that epigenetic factors due to the environments in which genes get expressed can themselves be responsible, quite literally, for the shape of our brains, and thence for the kinds of life we find ourselves able to lead. Wily Ulysses could adapt himself to face and overcome the many challenges his voyage threw at him, and so in principle can we. We need not choose between fatalism and a supernatural divine spark. There is open water between them.

There is also danger in supposing that because evolution by natural selection is the linchpin of modern biology, it can be applied with equal fertility and equal scientific credit elsewhere. A doubtful character on this stage is Richard Dawkins’s notion of a “meme” or unit of culture that survives in the Darwinian jungle in which things like songs, or fashions, or styles in art or architecture, ruthlessly compete until the biggest beasts of all finally triumph while others fall by the wayside. Dawkins’s idea has itself caught on, and there is certainly a kind of charm in the idea of a jungle of competing cultural objects, fighting it out for the prize of being taken up by the human beings who make up their environment. A librarian is a library’s way of making another library, after all.

But the first difficulty lies in the notion of advantage. In down-to-earth Darwinian explanations a feature of an organism can properly be thought of as an adaptation, that is, as conferring an advantage in coping with a problem the organism faces, only when we have a very good idea of the advantage in question. The colour of the polar bear’s coat helps its hunting because it blends with the environment; light sensitivity increases an organism’s capacity to respond to distant arrivals of predators, prey or mates; increasing length of neck enables giraffes to browse higher and guanacos to survive snowdrifts in the Patagonian winter. But we have no corresponding idea of what could count as an “advantage” to a song or style of dress. Indeed the whole idea sounds nonsensical.

And secondly when a song or a dance or a book or dress catches on all we can usually say is that “there must have been something about it” that assisted its catching on, but this is a post hoc judgment of no predictive or explanatory value. People talking of memes are no better at predicting fashion than the rest of us. After the event, sometimes, we can say that there must have been “something” – some need, some reason for catching on – but we do not know what it was. Abstract attempts to identify an unfilled niche in cultural space and then fill it are notoriously quixotic. So we are left only with the near-tautology that whatever catches on must have caught on for some reason. It may be an invitation for us to look for the reason, but it is not as it stands a piece of falsifiable or useful science.

Seeing ourselves as parts of nature can lead to worries about the extent of our own freedom and our own responsibility. These fears can be real enough, for there are limits to our powers. We find we cannot help but feel some ways, think some ways, hope for some things, avoid and fear others. But we also do not know what we can do until we try. When we face decisions we think of ourselves as free to decide, and that is a kind of clearing of the decks for the play of reason which in turn highlights one or another aspect of the situation, and sometimes one or another boundary to conduct we could put up with from ourselves or others. We literally take responsibility for our doings, and of course responsibility is imputed to us when our doings fall short. We cannot know in advance how well we can do, and freedom consists in trying to push that boundary ever further back.

When we fail, we may try excusing ourselves as the victims of genetic or environmental forces that were just too strong for us. But the excuse may ring hollow: it was we ourselves who let ourselves be overcome. Perhaps we could, and should, have tried harder. We cannot shelter behind the giant figure of Darwin when we try to avoid such uncomfortable thoughts. Again, the choice between hopeless fatalism and pessimism on the one hand, and a Divine spark on the other – let’s say between John Gray’s nihilism and Karen Armstrong’s case for God – is completely false.

As so often the most valuable role of the philosopher is to insist on the processes of interpretation, to remind us of the known complexities of human life, and to combat mistaken ideologies, however glorious their original inspiration in Darwin’s own imaginative, humane and cautious writings.

Simon Blackburn will be discussing the theory of “memes” as part of the BHA Conference “Evolutionary Theory: Is this all there is?” at London’s Conway Hall on 31 October.