Ridley's themes are the grandest that face humanity. By way of prologue: are our minds a tabula rasa when we are born? Or do we come ready-packed with specific preconceptions and proclivities - known broadly as "instincts"?
This was a key theme of philosophy long before Darwin and Mendel: John Locke, for example, favouring the tabula rasa; Plato conspicuously espousing the notion that we are born with a great deal in our heads. Both kinds of ideas, taken to extremes, have caused millions to be slaughtered or starved. Thus, over-belief in the role of genes in human nature led to the discipline of eugenics for which chairs were established at Oxford and at London - the latter of which, at University College, was discontinued only in the 1960s. Good left-wing intellectuals like H.G.Wells felt that those who were "black, brown, yellow, and dirty-white" should be stopped from breeding. Hitler took the notion to extremes; but it was the same notion.
Such memories have prompted enlightened moderns to deny the role of genes in shaping behaviour at all and to condemn the "genetic determinism" to which, they claim, the idea gives rise. But as Ridley points out, the opposite extreme - which he calls "cultural determinism" - has proved equally grotesque. Thus in Stalin's Russia Trofim Lysenko argued that Mendel was an evil subversive and that living things are shaped not by hypothetical "genes" but by their experiences. This appealed to politicians who wanted to mould Marxian creatures by Marxian politics. But although people might have seemed for a time to adapt to this political conceit, plants are less forgiving; when Lysenko subjected the Russian wheat crop to his theories, it perished, and millions starved.
Interestingly, it has become politically correct to remember and condemn the horrors of "genetic determinism" but to overlook the shortcomings of over-zealous "cultural determinism". Yet the truth as usual lies in between. Human beings are indeed born with "instincts" but these instincts are not determinist in nature. They are, as Ridley elegantly puts the matter, "predispositions to learn". Beyond doubt, we are equipped to learn some things (like language) much more easily than others (like maths). But where genes rough-hew, culture shapes the ends.
Ridley's next and larger brief is to ask whether our instincts, our predispositions to learn, push us towards goodness or badness. Again, philosophers have divided themselves down the middle, and people again have died in the clash of ideologies. A lineage extending from the Sophists of Greece to Thomas Henry Huxley, via St Augustine, Machiavelli and Thomas Hobbes, held that human beings are essentially selfish and act altruistically only to make themselves feel better. Another lineage, from Plato to Peter Kropotkin, most famously including Jean-Jaques Rousseau, suggests that human beings are innately benevolent, but are corrupted by society.
Modern Darwinian-Mendalian thinking takes the heat out of the issue. Yes, our behaviour is influenced by our genes and yes, as Richard Dawkins put it, our genes are "selfish"; and that seems bad news. Yet as Bill Hamilton began to show in the 1960s, our selfish genes can prompt us to behave unselfishly because they are selfish; that is, a gene will happily sacrifice the individual that possesses it in favour of a greater number of individuals who also harbour copies of itself. But of course, in many circumstances, our selfish genes can prompt us to behave selfishly. In short, we have it in us to be both good and bad. But then of course, G E Moore's warning of "naturalist fallacy" should always be heeded: the fact that our instincts prompt us to do any particular thing, does not make that thing right (or wrong).
In the end, the key task for all human beings is to get along with other human beings: we achieved biological success by sharing work and becoming individually specialised, but on the down side we need other people just as ants need other ants. In short, we need "society". But if society is simply what Thomas Huxley (paraphrasing Hobbes) called "a war of all against all" then the outlook seems grim. Fortunately, we have evolved devices for sociality just as we have evolved a capacity for altruism. As Bob Frank of Cornell has argued, natural selection favours those who form contracts, if only for the selfish reason that there is safety in numbers; and since contracts depend upon trust it is in the interests of each of us to demonstrate our trustworthiness.
Overall, says Ridley, the task is to define and foster a way of living that encourages what can properly be called our better instincts: our capacity for unselfishness and trust. His own suggestion is a return to a structure in which humans deal directly with other humans. It was through such interaction that the capacity for sociality first evolved; and only by such interaction can it be nurtured.
The new neodarwinian ideas are powerful, encouraging, and complex. They should be more widely understood, and it is a great pity that some of the people who write about them most conspicuously don't understand them at all. But Ridley is the real thing: a proper writer. He understands, enhances and conveys.