فصل 25

دوره: تاریخچه کوتاهی از فلسفه / درس 25

فصل 25

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chapter 25

Unintelligent Design

Charles Darwin

‘Are you related to monkeys on your grandmother’s or your grandfather’s side?’ This was Bishop Samuel Wilberforce’s cheeky question in a famous debate with Thomas Henry Huxley in Oxford’s Museum of Natural History in 1860. Huxley was defending the views of Charles Darwin (1809–82). Wilberforce’s question was meant to be both an insult and a joke. But it backfired. Huxley muttered under his breath, ‘Thank you God for delivering him into my hands’, and replied that he would rather be related to an ape than to a human being who held back debate by making fun of scientific ideas. He might just as well have explained that he was descended from monkey-like ancestors on both sides – not very recently, but some time in the past. That’s what Darwin claimed. Everyone has them in their family tree.

This view caused a great stir almost from the moment his book On the Origin of Species was published in 1859. After that it was no longer possible to think of human beings as completely different from the rest of the animal kingdom. Human beings weren’t special any more: they were just part of nature like any other animal. This might not come as a surprise to you, but it did to most Victorians.

You might think that all it would take to recognize our closeness to apes would be a few minutes spent in the company of a chimpanzee or gorilla or perhaps even a hard look in the mirror. But in Darwin’s day more or less everyone assumed that human beings were very different from any other animal and the idea that we shared distant relatives with them was ridiculous. There were plenty of people who thought that Darwin’s ideas were crazy and the work of the devil. Some Christians clung to their belief that the Book of Genesis gave the true story of how God created all the animals and plants in six busy days. God had designed the world and everything in it, each with its proper place for all time. These Christians believed that every species of animal and plant had remained the same since the Creation. Even today some people still refuse to believe that evolution is the process by which we came to be what we are.

Darwin was a biologist and a geologist, not a philosopher. So you might wonder why there is a chapter about him in this book. The reason it’s here is that his theory of evolution by natural selection and its modern versions have had a profound impact on how philosophers – as well as scientists – think about humanity. It is the most influential scientific theory of all time. The contemporary philosopher Daniel Dennett has called it ‘the single best idea anyone has ever had’. The theory explains how human beings and the plants and animals around them have come to be as they are and how they are all still changing.

One result of this scientific theory was that it became easier than ever before to believe that there is no God. The zoologist Richard Dawkins has written, ‘I can’t imagine being an atheist at any time before 1859, when Darwin’s On the Origin of Species was published.’ There were atheists, of course, before 1859 – David Hume, the subject of Chapter 17, was probably one – but there were many more afterwards. You don’t have to be an atheist to believe that evolution is true: many religious believers are Darwinists. But they can’t be Darwinists and believe that God created all species exactly as they are today.

As a young man, Darwin went on a five-year voyage on HMS Beagle, visiting South America, Africa and Australia. This was the adventure of his lifetime – as it would be for anyone. Before that he hadn’t been a particularly promising student, and no one would have expected him to make such an impressive contribution to human thought. He was no genius at school. His father was convinced that he was going to be a waster, and a disgrace to his family because he spent so much of his time hunting and shooting rats. As a young man he’d started training as a doctor in Edinburgh, but when that didn’t work out, he switched to studying divinity at Cambridge University, intending to become a vicar. In his spare time he was an enthusiastic naturalist, collecting plants and insects, but there were no signs that he was going to be the greatest biologist in history. In many ways he seemed a bit lost. He didn’t really know what he wanted to do. But the voyage of the Beagle transformed him.

The trip was a scientific expedition around the world, partly to map the coastlines of the places the ship visited. Despite his lack of qualifications, Darwin took on the role of official botanist, but he also made detailed observations of rocks, fossils and animals wherever they landed. The small ship quickly filled up with the samples he collected. Luckily he was able to send most of this collection back to England where it was stored ready for investigation.

By far the most valuable part of the voyage turned out to be the visit to the Galapagos Islands, a group of volcanic islands in the Pacific Ocean roughly 500 miles from South America. The Beagle reached the Galapagos Islands in 1835. There were plenty of interesting animals to examine there, including giant tortoises and sea-loving iguanas. Though it wasn’t obvious to him at the time, the most important for Darwin’s theory of evolution were a range of rather drab-looking finches. He shot a number of these small birds and sent them home for further examination. Close study later revealed that there were thirteen distinct species. The small differences between them were mostly in their beaks.

After his return, Darwin abandoned his plans of becoming a vicar. While he’d been travelling the fossils, plants and dead animals he’d sent back had made him quite famous in the scientific world. He became a full-time naturalist and spent many years working on his theory of evolution as well as becoming a world expert on barnacles, those small limpet-like animals that cling to rocks and the hulls of ships. The more he thought about it, the more he was convinced that species evolved through a natural process and were constantly changing rather than fixed for all time. Eventually he came up with the suggestion that plants and animals that were well suited to their environment were more likely to survive long enough to pass on some of their characteristics to their young. Over long periods this pattern produced plants and animals that seemed to have been designed to live in the environments in which they were found. The Galapagos Islands provided some of the best evidence of evolution in action. For example, at some point in history, he thought, finches had found their way there from the mainland, perhaps carried by strong winds. Through many thousands of generations, the birds on each island had then gradually adapted to where they were living.

Not all birds of the same species are identical. There’s usually quite a lot of variety. One bird might have a slightly more pointed beak than another, for instance. If having this kind of beak helped the bird survive longer, it would be more likely to breed. For example, a bird that has a beak that is good for eating seeds would do well on an island where there were many seeds around, but probably not so well on an island where the main source of food is from nuts that needed to be cracked. A bird that had a harder time finding food because of its beak shape would find it difficult to survive long enough to mate and produce offspring. That made it less likely that that type of beak would be passed on. Birds with beaks that suited the available food supplies would be more likely to pass that feature on to their offspring. So on a seed-rich island, the birds with good beaks for eating seeds came to dominate. Over many thousands of years this led to a new species evolving, one that was very different from the original type that landed on the island. Birds with the wrong types of beak would have gradually died out. On an island with different conditions a slightly different sort of finch would evolve. Over long periods of time the birds’ beaks became better and better adapted to their environment. The varying environments on different islands meant that the birds that thrived were the ones best suited to that place.

Other people before Darwin, including his grandfather Erasmus Darwin, had suggested that animals and plants had evolved. What Charles Darwin added was the theory of adaptation by natural selection, the process that leads the best-adapted to survive to pass on their characteristics.

This struggle for survival explains everything. It isn’t just a struggle between members of different species; members of the same species struggle against each other too. They are all in competition to pass on their own characteristics to the next generation. This is how features of animals and plants that look as if they have been invented by an intelligent mind have come about.

Evolution is a mindless process. It has no consciousness or God behind it – or at least it doesn’t need to have anything like this behind it. It is impersonal: like a machine that keeps working automatically. It is blind in the sense that it doesn’t know where it is going and it doesn’t think about the animals and plants that it produces. Nor does it care about them. When we see its products – plants and animals – it’s difficult not to think of them as cleverly designed by someone. But that would be a mistake. Darwin’s theory provides a much simpler and more elegant explanation. It also explains why there are so many types of life, with different species adapting to the parts of the environment they live in.

In 1858 Darwin still hadn’t got round to publishing his findings. He was working on his book – he wanted to get it just right. Another naturalist, Alfred Russel Wallace (1823–1913), wrote to him sketching his own, very similar theory of evolution. This coincidence nudged Darwin into going public with his ideas, first with a presentation to the Linnean Society in London, and then the next year, 1859, with his book On the Origin of Species. After devoting a large part of his life to working out his theory, Darwin didn’t want Wallace to get there before him. The book instantly made him famous.

Some people who read it were unconvinced. The captain of the Beagle, Robert FitzRoy, for example, a scientist himself and inventor of a system of weather forecasting, was a devout believer in the biblical story of Creation. He was dismayed that he had played a part in undermining religious belief, and wished he’d never taken Darwin on board his ship. Even today, there are creationists who believe that the story told in Genesis is true and a literal description of the origin of life. But among scientists there is overwhelming confidence that Darwin’s theory explains the basic process of evolution. This is partly because since Darwin’s time there has been a mass of new observations in support of the theory and of later versions of it. Genetics, for example, has given a detailed explanation of how inheritance works. We know about genes and chromosomes and about the chemical processes involved in passing on particular qualities. The fossil evidence today is also far more convincing than it was in Darwin’s day. For all these reasons the theory of evolution by natural selection is much more than ‘just a hypothesis’: it is a hypothesis that has a very substantial weight of evidence in its support.

Darwinism may have more or less destroyed the traditional Design Argument and shaken many people’s religious faith. But Darwin himself seems to have kept an open mind on the question of whether or not God exists. In a letter to a fellow scientist he declared that we aren’t really up to coming to a conclusion on the issue: ‘the whole subject is too profound for human intellect,’ he explained: ‘A dog might as well speculate on the mind of Newton.’ A thinker who was prepared to speculate about religious faith, and, unlike Darwin, made it central to his life’s work, was Søren Kierkegaard.

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