Two or three centuries ago, most of the common people of Europe believed in God, while a small bunch of intellectuals were convinced this was a delusion. For some of these scholars, however, it was a delusion of a mightily convenient kind. Religious faith played a key role in maintaining social order, and so was not to be brutally exposed as bogus. The truth can be wantonly destructive, and not everyone is tough-minded enough to take it. Voltaire was famously anxious about the effects of his own religious scepticism on his domestic servants. Plenty of Victorian agnostics clambered into a pew in the belief that behaving as though there was a God would keep society on the rails. As Friedrich Nietzsche was among the first to recognise, an increasingly secular civilisation had killed God off; but it had disowned its act of deicide and pretended he was still alive.

There is a similar doublethink in our own time, but it is now freedom, not God, which is at stake. Rarely has the idea of freedom been so popular in practice and so disdained in theory. Almost everyone assumes that they are free, except for a small band of neuroscientists and geneticists for whom neural firings or inherited genes lie at the root of everything we do, including our sentimental attachment to the myth of free will. For them, as Julian Baggini remarks in this excellent book, “consciousness is just the noise made by the firing of neurons”. Like the closet atheists of Victorian England, however, these people continue to choose from menus, vote Lib Dem or select posh schools for their children, for all the world as though they were possessed of the very liberty they deny. For them, social existence is one enormous fiction, in which we suspend our theoretical disbelief in free will and pitch in with the deluded, freedom-loving masses for the sake of a quiet life.

Yet some of the versions of freedom these scientists throw out are not worth having in the first place. No reputable philosopher for a very long time has taught that when we decide to put the cat out, we make something called a conscious act of will a millisecond before we rise from our armchairs. To say that I downed the glass of Scotch freely is to say that nobody was holding a gun to my head. It is to describe a situation, not report on an inner experience. Free will in this sense is most certainly a myth, and one, as Baggini points out, that was scarcely known to the thinkers of antiquity. He might have added that for a medieval thinker such as Thomas Aquinas, the will is a matter of love and desire, not of steel-hard determination.

Equally vacuous is the idea that freedom consists in a total absence of constraint, as in the callow postmodern cult of “options” (the future, one postmodern thinker excitedly remarked, will be just like the present, only with more options). On this theory, the individual confronts a range of possibilities with complete freedom to decide among them. The only problem with this, as Baggini argues, is that such an individual would not be a human subject at all. We decide what to do on the basis of our values, beliefs, temperament, conditioning, predilections and the like – which is to say that it is we who decide, not some blank space. To be entirely free of such constraints would mean that you had no basis at all on which to choose.

What, however, if our beliefs and desires lead us to act in a way that feels inevitable? Can we still be free if we could not have acted otherwise? Baggini is surely right to claim that we can. In fact, most of the things that matter – being in love, composing a superb sonata, detesting Piers Morgan, feeling horrified by the slave trade – have a smack of inner necessity about them, as this book argues in a perceptive chapter on art. What define the self most deeply are the sort of commitments from which we could not walk away even if we tried. The point, however, is that we don’t want to. Freedom from such engagements would be no freedom at all. True liberty lies in being able to realise such a self, not shuck it off.

Most critics of free will assume too readily that it draws on a disreputable idea of human autonomy. To be free is to be absolved from all determining influences – to be self-generating, self-dependent and absolutely self-responsible. This is not so much a philosophical theory as American ideology. A belief in absolute responsibility is one reason why so many Americans languish on death row. The truth is that without an enormous amount of dependency – on our parents, culture, language, nature and so on – we could never achieve the mildest degree of independence. Freedom is not a question of being released from the forces that shape us, but a matter of what we make of them. The world, however, is now divided down the middle between off-the-wall libertarians who deny the reality of such forces, and full-blooded determinists such as the US convict Stephen Mobley, who 20 years ago tried to avoid execution for the murder of a pizza store manager by claiming that it was the result of a mutation in his monoamine oxidase A gene. It wasn’t the smartest way to appeal to a jury of citizens likely to endorse Oprah Winfrey’s view that “we’re responsible for everything that happens to us”.

Men and women aren’t authors of themselves, as a character in Shakespeare’s Coriolanus remarks of its proud protagonist, but neither are they slaves of their genes. When Richard Dawkins describes human beings as “survival machines – robot vehicles blindly programmed to preserve the selfish molecules known as genes”, his language is redolent of neoliberal capitalism as well as the scientist’s laboratory. To see people in this demeaning way is simply the flipside of the idealising talk of pure autonomy. If the former captures something of the bleak reality of the marketplace, the latter belongs to the heady rhetoric that helps to legitimate it.

Some neuroscientists imagine they have dispatched the idea of freedom to the outer darkness by mapping the unconscious processes underlying our conscious decisions. If they were not so allergic to Freud, who speaks of unconscious intentions, they might recognise that this is as much stale news as many another supposedly novel insight. Anyway, as this book asks, why should free choices be exclusively conscious ones? A great many factors conspire to shape our decisions, some rational and some emotional, some cultural and some temperamental, some conscious and some not.

Do you genes determine your entire life? | Julian Baggini Read more

A lot of neuroscience seeks to reduce decisions to behaviour in the brain. But we act according to reasons as well as neurological causes, and reasons are a question of meaning, which in turn involves the inescapably creative business of interpretation. No doubt this is one reason why meaning isn’t exactly a hot topic in the laboratories these days. The primary model of human creativity is language, which, like art, dismantles the distinction between freedom and necessity. Grammars constrain what it is possible for us to say, but they also generate utterances that can’t simply be read off from them. Language isn’t productive because of some transcendent principle or ghost in the linguistic machine that overrides its constraints. On the contrary, a certain self-surpassing is built into the system itself.

For most people, Freedom Regained will seem like a kind of Maginot line, defending a territory that is not under attack. This, however, is because the new enemies of freedom are not much evident in everyday life. They are mild-mannered, soft-spoken men and women in senior common rooms, not wild-eyed dictators raving through public address systems. Among its other virtues, the book reveals how many of these soft-spoken types engage in one of the oldest of all debating devices: setting up a straw man of the concept under fire so as the more conveniently to bowl it over. It is just what Dawkins does with God.

• Terry Eagleton’s Culture and the Death of God is published by Yale. To order Freedom Regained: The Possibility of Free Will for £11.99 (RRP £14.99) visit bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.