Image copyright Rex Features Image caption Benedict Cumberbatch and Johnny Lee Miller in the 2011 National Theatre production of Frankenstein

People have long dreamed of improving humanity through science, but what results might no longer be human, argues the philosopher John Gray.

More than 70 years ago, the Oxford linguist, writer of fantasy fiction and theologian CS Lewis wrote:

Man's conquest of nature, if the dreams of some scientific planners are realized, means the rule of some hundreds of men over billions upon billions of men. Each new power won by men is a power over man as well. There neither is nor can be any simple increase of power on Man's side. Each increase leaves him weaker as well as stronger.

Lewis made these observations in a short book which he published in 1943, called The Abolition of Man.

The target of his reflections was the agenda for education being promoted by progressive thinkers at the time, who aimed to debunk traditional values, which they saw as dated, unenlightened and irrational.

But these thinkers, Lewis argued, had no standard of what was to count as progress. They thought of it as meaning the increasing human power over Nature that comes with advancing scientific knowledge.

However, Lewis pointed out, this power is exercised over other human beings as much as the planet. Using the knowledge science has given them, governments and corporations alter the planetary environment to create the world in which future generations must live. The conquest of Nature means, in reality, conquering these future human beings.

Clive Staples Lewis (1898-1963)

Novelist, critic, academic and theologian - born in Belfast, he held positions at Oxford and Cambridge Universities

Most famous for his Narnia sequence of children's novels, including The Lion, The Witch And The Wardrobe

Wrote several well-received books on Christianity, and lectured and broadcast about his faith

His marriage to Joy Gresham, and her death, provided the subject for William Nicholson's successful play and film Shadowlands

BBC Religion & Ethics Profile: C.S. Lewis

Lewis goes on to consider what he describes as the final stage in this process, which comes with the attempt to alter the human species itself.

The scientific planners of Lewis's generation were dissatisfied with existing humankind. Using new techniques, they were convinced, they could design a much improved version of the species.

Eugenics, pre-natal conditioning and new methods in education could fashion a type of human being as good, or better, than any that had existed before. But, Lewis asks, what standards will the scientific planners use in moulding this new humanity?

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John Gray is a political philosopher and author of False Dawn: The Delusions of Global Capitalism Listen to A Point of View on the iPlayer BBC Podcasts - A Point of View

To begin with, they may use traces of the traditional values they have been so busy debunking, but since these values are in many cases rooted in religion, which they view as irrational, this won't last long. Instead the planners may aim to increase human longevity - not only that of individuals, but also of the human species.

But why should our species be preserved? Why not design and create a different species that is smarter, more powerful and longer lasting than humans? After all, if humankind stands in the way of progress, what is the point of being human? Lewis concludes: "Man's final conquest has proved to be the abolition of man."

Lewis's questions are as relevant now as they were when he asked them in the 1940s - if not more so. While the scientific knowledge needed to remould humanity hardly existed then, it is rapidly developing at the present time.

When Lewis talked about eugenics and pre-natal conditioning as the means for making a new species, he was invoking Aldous Huxley's Brave New World rather than the science of his time.

Today it is the sciences of bioengineering and artificial intelligence that promise the power to remake humankind. Scientists differ as to how realistic the prospect may be. But there are many people who welcome the possibility of transforming the human species that actually exists into something that matches their dreams.

The idea that humans can use science to create superior versions of themselves is not at all new. It was prefigured in the ancient myth of the Golem - an artificial person created by magic from dust or mud.

Golems are commonly pictured as shambling, half-human creatures - a tradition that was developed further by Mary Shelley in her novel Frankenstein, published in 1818, where the artificial human being is a tragic figure.

These myths and fictions carried a warning - the attempt to create an artificial human being risked making a monster. But the idea was revived in the 20th Century, and not only in the realm of the imagination.

The Nazis dreamt of creating a new type of human being through what they described as "scientific breeding" - a process that was meant to run in parallel with the elimination of people regarded as "unfit" or "racially impure".

The Golem

Image copyright Getty Images

Legendary figure believed to have its roots in Jewish folklore - a being made out of clay and given life

Most famous version of the story concerns Rabbi Judah Loew ben Bezalel of Prague, who created a golem to protect the city's Jewish population from anti-Semitic attacks

The character has appeared in works by writers including Terry Pratchett, Jorge Luis Borges, and Cythia Ozick, as well as Marvel comics and The Simpsons

Several film versions of the story have been made, including the 1915 silent film The Golem (pictured)

The belief that humanity could and should be improved through eugenics - the use of science to improve the quality of the human population through selective breeding - wasn't confined to the Nazis. Eugenics was promoted by many progressive writers and thinkers, including - at some stages in their careers - HG Wells, Bertrand Russell and Julian Huxley.

In the former Soviet Union, Leon Trotsky in his pamphlet Literature and Revolution, published in 1923, looked forward to a time when the human species would be transformed by scientific experimentation: "Even the purely physiologic life will become subject to collective experiments. The human species, the coagulated Homo Sapiens, will once more enter into a state of radical transformation, and, in our own hands, will become the object of the most complicated methods of artificial selection and psycho-physical training."

In future, Trotsky believed: "The average human type will rise to the heights of an Aristotle, a Goethe or a Marx."

Image copyright Getty Images Image caption Soviet revolutionary Leon Trotsky believed humankind could be improved through science

Today the dream of using science to fashion a new type of human being is, if anything, even more ambitious. There are some, like Trotsky, who see their goal as that of enhancing human abilities, so that larger numbers can achieve what only a few did in the past. But there are also those who want to bring about a mutation in the species itself.

The futurologist Ray Kurzweil, now director of engineering at Google, anticipates a time when, by merging their minds with the much greater artificial intelligence that they have created in computers and uploading the result into cyberspace, human beings will cease to be biological organisms. Eventually, he believes, these post-human minds may coalesce into a super-mind, godlike in its powers and potentially immortal.

Humans are not intelligent enough to be capable of designing superior versions of themselves

The question isn't whether this is technologically possible but instead whether such a transformation is desirable.

Whatever emerges from it won't be human. A bodiless mind that doesn't age or die isn't a human being. Like the shades who wander through the afterlife in some religions, it's a fading trace of what a human being once had been.

Strangely, human beings have often looked hopefully to surviving death in a form that would leave them unrecognisably different from what they were in life.

When Lewis published his prophetic essay, he'd been a convert to Christianity for more than a decade. But you don't need to accept Lewis's theological beliefs to acknowledge the danger he foresaw.

Humans are not intelligent enough to be capable of designing superior versions of themselves. If they acquire the power to remake themselves, the result will be a proliferation of the types of human being that are currently fashionable - today, the super-smart and the preternaturally thin. As Lewis predicted, one generation will be exercising power over future generations by modelling them according to the dictates of ephemeral fads.

Image copyright ALAMY Image caption "Improving" human beings could just mean copying current fads about body shape

There may be some who welcome such a world. And it may have some points in its favour, such as the elimination of inheritable diseases.

But the risk of programmes of human enhancement is that they end by flattening out individuality and diversity - qualities that make us human.

If at some unknown point in the future it becomes feasible to remould ourselves according to our dreams, the result can only be an impoverishment of the human world. Going further and enhancing human powers to the point where what results ceases to be recognisably human is, in effect, a project that aims for human extinction - as Lewis put it, the abolition of man.

Those who want to fashion a radically improved version of the human animal end up wanting to leave behind our species as it has always been.

For myself, unregenerate humanity is preferable - the flawed and conflicted creatures we are in fact are much more interesting than the transformed creatures we'd like to be. But I'm sure we're not done with trying. For if anything is peculiarly human, it's the refusal to be what we are.

A Point of View is broadcast on Fridays on Radio 4 at 20:50 BST and repeated Sundays 08:50 BST

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