Free will, as it has classically been defined, is the capacity to "do otherwise". Professor Steve Jones, from University College London, states in his book In the Blood: "Humans are, in the end, animals: for any pattern of behaviour, the question is not whether biology is involved, but how."
This is the paradox of free will phrased in the language of science: if our appearance, personality and behaviour are controlled by genes that we have inherited, and we live in a physical environment that can be measured and calculated, freedom of will may be an illusion generated by a brain created by the interaction of 30,000 genes. We may think we are choosing; in reality, we could not do otherwise than we do.
Before modern genetics, free will was solely the prerogative of the Church. The fourth-century British theologian Pelagius argued that Man is responsible for his actions, be they good or evil. The Church saw this as a dangerous position, since it minimised the role of God and the power of the Church, and the author was excommunicated for his pains. The current position of the Catholic Church is that we are responsible for our own decisions, and can reject God if we choose. St Augustine said: "God who made us without our consent cannot save us without our consent."
But the answer to the problem may well lie in the heartland of biology, rather than philosophy or theology. That our world is mechanistic and can be predetermined to some extent is an argument put forward by Professor Edward Wilson, of Harvard University, in his book On Human Nature.
It is possible to imagine a computer that might be able to predict whether a coin would land heads or tails. This computer would measure the physical properties of a coin to the exact micron, analyse the contours of a person's thumb, her muscle physiology, the air currents of the room, and the microtopography and resilience of the table the coin will land upon. At the moment the coin is released, the force and angle of the flip are fed into a computer. Before the coin has spun through more than a few revolutions, the computer reports the expected full trajectory of the coin and its final resting position. The computer's predictions wouldn't be error-free, but it might be possible to foretell the coin's final destination at a rate well above chance.
Predicting the path of a coin is small beer compared to the flight of a bird, or the song of a whale. Surely, it is not possible to map out the behaviour of an animate creature with desires and motivations of its own? Wilson thinks it is. Imagine a honey bee, that will die before it's 50 days old; during this time, it will have created a map in its mind's eye of the area where it lives, and it can recognise the odour of its nest mates, and the quality of nectar of several hundred kinds of flower. If a bee is held in the palm of the hand and then tossed into the air, it appears to be a free agent, bound to travel where it wills.
But, Wilson says: "If we were to concentrate all we know about the physical properties of thimble-sized objects, the nervous system of insects, the behavioural peculiarities of honey bees, and the personal history of this particular bee, and if the most advanced computational techniques were brought to bear, we might predict the flight path of the bee with an accuracy that exceeds pure chance. To the circle of human observers watching the computer read-out, the future of the bee is determined to some extent. But in her own `mind', the bee, which is isolated permanently from such human knowledge, will always have free will."
This, then, could be the crux of the issue: if we had a computer big enough, and took enough measurements, we could know the unknowable, and be able to chart the destiny of human beings who are programmed by their genes. Wilson says: "It is entirely possible that the will - the soul, if you wish - emerged through the evolution of physiological mechanisms... So, for the moment, the paradox of determinism and free will appears not only resolvable in theory, it might even be reduced in status to an empirical problem in physics and biology."
If our behaviour is inherently knowable, and the issue is merely limited by technology, why do we harbour the illusion that we have free will? Could there be a gene for free will, which allows us to act apparently randomly? This would be the ultimate irony of ironies, the determinism of the indeterminable. According to Dr Geoffrey Miller, of University College London, we could have a randomising mechanism in our head, a roulette wheel in the brain. It gives us the "capacity for rapid, unpredictable generation of highly variable alternatives", says Dr Miller.
This mechanism might work by generating random numbers the way a computer works, or it could amplify the quantum mechanical noise in synaptic activity. Either way, a quick spin of the wheel and we produce art or music, act a little insane, lose our temper over trivialities - in short, we become unpredictable.
But random behaviour is not free will. Free will is the ability to choose. Professor Daniel Dennett, a philosopher at Tufts University, argues that it is language which allows us to do this. "[Language] gives us the capacity to represent to ourselves futures even beyond our own deaths," he says. "Our capacity to entertain projects that have meanings goes so far in space and time - orders of magnitude ahead of other creatures - and it's this meaning that matters, that interests us, and that's why our freedom is much more interesting than [that of] the birds that fly in the sky, or the whales that roam the sea without running into a fence... But if you can't frame interesting desires, then your freedom's really negligible."
Yet many scientists would argue, first, that language is itself a product of our genes, and second, that given our use of language as a particular person, with a particular set of genetic attributes, we could not do or think otherwise than we do. Professor Steven Rose, of the Open University, has written a book on biological determinism. In Lifelines, he believes he can offer a solution, one that highlights the importance of genes but does not subscribe to a narrow genetic determinism. He points out that half the human population between the ages of 13 and 50 are subject to monthly hormonal cycles that can effect their lives quite radically. A further example of the interaction of genes and environment comes from the study of proteins. Proteins comprise about a tenth of our body weight, and each of our protein molecules will survive for only a fortnight. The net effect is that every hour of every day, an ounce (28g) of protein is being manufactured to compensate for this loss - that's a billion, billion molecules of protein every minute of our adult life.
"The odds are always changing at all levels, from the molecular through the individual to the population and species... Thus, for humans, as for other living organisms, the future is radically unpredictable," says Professor Rose. Humans are not free spirits constrained only by the limits of our imaginations; neither are we robots programmed by our genes to replicate our DNA. As Rose says: "This means that we have the ability to construct our own futures, albeit in circumstances not of our choosing. And it is therefore our biology that makes us free."
The author's novel, `Angel Bird', about a zoologist who believes there is no free will, is published by Black Swan, price pounds 6.99Reuse content