Science of Discworld III Read online

  Evolution, then, is a theory, one of the most influential, far-reaching and important theories ever devised. In this context, it’s worth pointing out that the word ‘theory’ is often used in a quite different sense, to mean an idea that is proposed in order to be tested. Strictly speaking, the word that should be used here is ‘hypothesis’, but that’s such a fussy, pedantic-sounding word that people tend to avoid it. Even scientists, who should know better. ‘I have a theory,’ they say. No, you have a hypothesis. It will take years, possibly centuries, of stringent tests, to turn it into a theory.

  The theory of evolution was once a hypothesis. Now it is a theory. Detractors seize on the word and forget its dual use. ‘Only a theory,’ they say dismissively. But a true theory cannot be so easily dismissed, because it has survived so much rigorous testing. In this respect there is far more reason to take the theory of evolution seriously than any explanation of life that depends on, say, religious faith, because falsification is not high on the religious agenda. Theories, in that sense, are the best established, most credible parts of science. They are, by and large, considerably more credible than most other products of the human mind. So what these people are thinking of when they chant their dismissive slogan should actually be ‘only a hypothesis’.

  That was a defensible position in the early days of the theory of evolution, but today it is merely ignorant. If anything can be a fact, evolution is. It may have to be inferred from clues deposited in the rocks, and more recently by comparing the DNA codes of different creatures, rather than being seen directly with the naked eye in real time, but you don’t need an eyewitness account to make logical deductions from evidence. The evidence, from several independent sources (such as fossils and DNA), is overwhelming. Evolution has been established so firmly that our planet makes no sense at all without it. Living creatures can, and do, change over time. The fossil record shows that they have changed substantially over long periods of time, to the extent that entirely new species have arisen. Smaller changes can be observed today, over periods as short as a year, or mere days in bacteria.

  Evolution happens.

  What remains open to dispute, especially among scientists, is how evolution happens. Scientific theories themselves evolve, adapting to fit new observations, new discoveries, and new interpretations of old discoveries. Theories are not carved in tablets of stone. The greatest strength of science is that when faced with sufficient evidence, scientists change their minds. Not all of them, for scientists are human and have the same failings as the rest of us, but enough of them to allow science to improve.

  Even today there are diehards – not a majority, despite the noise they make, but a significant minority – who deny that evolution has ever occurred. Most of them are American, because a quirk of history (coupled with some idiosyncratic tax laws) has made evolution into a major educational issue in the United States. There, the battle between Darwin’s followers and his opponents is not just about the intellectual high ground. It is about dollars and cents, and it is about who influences the hearts and minds of the next generation. The struggle masquerades as a religious and scientific one, but its essence is political. In the 1920s four American states (Arkansas, Mississippi, Oklahoma, and Tennessee) made it illegal to teach children about evolution in public schools. This law remained in place for nearly half a century: it was finally banned by the Supreme Court in 1968. This has not stopped advocates of ‘creation science’ from trying to find ways round that decision, or even to get it reversed. Largely, however, they have failed, and one reason is that creation ‘science’ is not science; it lacks intellectual rigour, it fails objective tests, and at times it is plain nutty.

  It is possible to maintain that God created the Earth, and no one can prove you wrong. In that sense, it is a defensible thing to believe. Scientists may feel that this ‘explanation’ doesn’t greatly help us understand anything, but that’s their problem; for all anyone can prove, it could have happened that way. But it is not sensible to follow the Anglo-Irish prelate James Ussher’s biblical chronology and maintain that the act of creation happened in 4004 BC, because there is overwhelming evidence that our planet is far older than that – 4.5 billion years rather than 6000. Either God is deliberately trying to mislead us (which is conceivable, but does not fit well with the usual religious messages, and may well be heretical) or we are standing on a very old lump of rock. Allegedly, 50 per cent of Americans believe that the Earth was created less than 10,000 years ago, which if true says something rather sad about the most expensive education system in the world.

  America is fighting, all over again, a battle that was fought to a finish in Europe a century ago. The European outcome was a compromise: Pope Pius XII did accept the truth of evolution in an encyclical of 1950, but that wasn’t a total victory for science.2 In 1981 a successor, John Paul II, gently pointed out that ‘The Bible … does not wish to teach how the heavens were made, but how one goes to heaven.’ Science was vindicated, in that the theory of evolution was generally accepted, but religious people were free to interpret that process as God’s way of making living creatures. And it’s a very good way, as Darwin realised, so everyone can be happy and stop arguing. Creationists, in contrast, seem not to have appreciated that if they pin their religious beliefs to a 6000-year-old planet, they are doing themselves no favours and leaving themselves no real way out.

  Darwin’s Watch is about a Victorian society that never happened – well, once the wizards interfered, it stopped having happened. It is not the society that creationists are still attempting to arrange, which would be far more ‘fundamentalist’, full of self-righteous people telling everyone else what to do and stifling any true creativity. The real Victorian era was a paradox: a society with a very strong but rather flexible religious base, where it was taken for granted that God existed, but which gave birth to a whole series of major intellectual revolutions that led, fairly directly, to today’s secular Western society. Let us not forget that even in the USA there is a constitutional separation of the state from the Church. (Strangely, the United Kingdom, which in practice is one of the most secular countries in the world – hardly anyone attends church, except for christenings, weddings, and funerals – has its own state religion, and a monarch who claims to be appointed by God. Unlike Discworld, Roundworld doesn’t have to make sense.) At any rate, the real Victorians were a God-fearing race, but their society encouraged mavericks like Darwin to think outside the loop, with far-reaching consequences.

  *

  The thread of clocks and watches runs right across the metaphorical landscape of science. Newton’s vision of a solar system running according to precise mathematical ‘laws’ is often referred to as a ‘clockwork universe’. It’s not a bad image, and the orrery – a model solar system, whose cogwheels make the tiny planets revolve in some semblance of reality – does look rather like a piece of clockwork. Clocks were among the most complicated machines of the seventeenth and eighteenth centuries, and they were probably the most reliable. Even today, we say that something functions ‘like clockwork’; we have yet to amend this to ‘atomic accuracy’.

  By the Victorian age, the epitome of reliable gadgetry had become the pocket-watch. Darwin’s ideas are intimately bound up with a watch, which again plays the metaphorical role of intricate mechanical perfection. The watch in question was introduced by the clergyman William Paley, who died three years after Darwin was born. It features in the opening paragraph of Paley’s great work Natural Theology, first published in 1802.3 The best way to gain a feeling for his line of thinking is to use his own words:

  In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that for anything I knew to the contrary, it had lain there forever: nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of th
e answer which I had before given, that, for anything I knew, the watch might have always been there. Yet why should not this answer serve for the watch as well as for the stone? Why is it not as admissible in the second case, as in the first? For this reason, and for no other, viz. that, when we come to inspect the watch, we perceive (what we could not discover in the stone) that its several parts are framed and put together for a purpose, e.g. that they are so formed and adjusted as to produce motion, and that motion so regulated as to point to the hour of the day; that if the different parts had been differently shaped from what they are, of a different size from what they are, or placed after any other manner, or in any other order, than that in which they are placed, either no motion at all could have been carried on in the machine, or none which would have answered the use that is now served by it.

  Paley goes on to elaborate the components of a watch, leading to the crux of his argument:

  This mechanism being observed … the inference, we think, is inevitable; that the watch must have had a maker; that there must have existed, at sometime, and at some place or other, an artificer or artificers, who formed it for the purpose which we find it actually to answer; who comprehended its construction, and designed its use.

  There then follows a long series of numbered paragraphs, in which Paley qualifies his argument more carefully, extends it to cases where, for instance, some parts of the watch are missing, and dismisses several objections to his reasoning. The second chapter takes up the story by describing a hypothetical ‘watch’ that can produce copies of itself – a remarkable anticipation of the twentieth-century concept of a Von Neumann machine. There would still be good reason, Paley states, to infer the existence of a ‘contriver’; in fact, if anything, the effect would be to enhance one’s admiration for the contriver’s skill. Moreover, the intelligent observer

  would reflect, that though the watch before him were, in some sense, the maker of the watch which was fabricated in the course of its movements, yet it was in a very different sense from that in which a carpenter, for instance, is the maker of a chair.

  He continues to develop this thought, and disposes of one possible suggestion: that, just as a stone might always have existed, for all he knew, so a watch might have always existed. That is, there might have been a chain of watches, each made by its predecessor, going back infinitely far into the past, so that there never was any first watch. However, he tells us, a watch is very different from a stone: it is contrived. Perhaps stones could always have existed: who knows? But not watches. Otherwise we would have ‘contrivance, but no contriver; proofs of design, but no designer’. Rejecting this suggestion on various metaphysical grounds, Paley states:

  The conclusion which the first examination of the watch, of its works, construction, and movement, suggested, was, that it must have had, for the cause and author of that construction, an artificer, who understood its mechanism, and designed its use. This conclusion is invincible. A second examination presents us with a new discovery. The watch is found, in the course of its movement, to produce another watch, similar to itself: and not only so, but we perceive in it a system or organisation, separately calculated for that purpose. What effect would this discovery have, or ought it to have, upon our former inference? What, as hath already been said, but to increase, beyond measure, our admiration of the skill which had been employed in the formation of such a machine!

  Well, we can all see where the good reverend is leading, and he homes in on his target in his third chapter. Instead of a watch, consider an eye. Not lying on a heath, but in an animal, which perhaps does lie on a heath. What he does say is: compare the eye to a telescope. There are so many similarities that we are forced to deduce that the eye was ‘made for vision’, just as the telescope was. Some thirty pages of anatomical description reinforce the contention that the eye must have been designed for the purpose of seeing. And the eye is just one example: consider a bird, a fish, a silkworm, or a spider. Now, finally, Paley states explicitly what all his readers knew was coming from page one:

  Were there no example in the world of contrivance except that of the eye, it would be alone sufficient to support the conclusion which we draw from it, as to the necessity of an intelligent Creator.

  There we have it, in a nutshell. Living creatures are so intricate, and function so effectively, and fit together so perfectly, that they can have arisen only by design. But design implies a designer. Ergo: God exists, and it was He who created Earth’s magnificent panoply of life. What more is there to say? The proof is complete.

  1 So called because it starts from the phenomenon of design and deduces the existence of a cosmic designer.

  2 According to Isaac Asimov, the most practical and dramatic victory of science over religion occurred in the seventeenth century, when churches began to put up lightning conductors.

  3 It is old enough to use the elongated s’s parodied in Diſcworld as ſs. We have reſiſted temptation except in this footnote. Though ‘manifeſtation of deſign’ does have a bit of a cachet.

  THREE

  THEOLOGY OF SPECIES

  IT WAS THREE HOURS LATER …

  The senior wizards trod carefully in the High Energy Magic Building, partly because it wasn’t their natural habitat, but also because most of the students who frequented it used the floor as a filing cabinet and, distressingly, as a larder. Pizza is quite hard to remove from a sole, especially the cheese.

  In the background – always in the background in the High Energy Magic Building – was Hex, the university’s thinking engine.

  Occasionally, bits of it, or possibly ‘him’, moved. Ponder Stibbons had long ago given up trying to understand how Hex worked. Possibly Hex was the only entity in the university who understood how Hex worked.

  Somewhere inside Hex magic happened. Spells were reduced, not to their component candles and wands and chants, but to what they meant. It happened too fast to see, and perhaps too fast to understand. All that Ponder was certain about was that life was intimately involved. When Hex was thinking deeply there was a noticeable hum from the beehives along the back wall, where slots gave them access to the outside world, and everything completely ceased to work if the ant colony was removed from its big glass maze in the heart of the machine.

  Ponder had set up his magic lantern for a presentation. He liked making presentations. For a brief moment in the chaos of the universe, a presentation made everything sound as if it was organised.

  ‘Hex has run the history of Roundworld against the last copy,’ he announced, as the last wizard sat down. ‘He has found significant changes beginning in what was known as the nineteenth century. Slide, please, Rincewind.’ There was some muffled grumbling behind the magic lantern and a picture of a plump and elderly lady appeared on the screen. ‘This lady is Queen Victoria, ruler of the Empire of the British.’

  ‘Why is she upside down?’ said the Dean.

  ‘It could be because with a globe there is technically no right way up,’ said Ponder. ‘But I’m hazarding that it got put in wrong. Next slide, please. With care.’ Grumble, click. ‘Ah, yes, this is a steam engine. The reign of Victoria was notable for great developments in science and engineering. It was a very exciting time. Except … next slide, please.’ Grumble, click.

  ‘Wrong slide, that man!’ said Ridcully. ‘It’s just blank.’

  ‘Aha, no, sir,’ said Ponder, gleefully. ‘That is a dynamic way of showing you that the period I just described turns out not, in fact, to have happened. It should have, but it didn’t. On this version of the Globe, the Empire of the British did not become as big, and the other developments were all rather muted. The great wave of discovery flattened out. The world settled down to a period of stability and peace.’

  ‘Sounds good to me,’ said Ridcully, and got a chorus of ‘hear, hears’ from the other wizards.

  ‘Yes, Archchancellor,’ said Ponder. ‘And, then again, no. Getting off the planet, remember? The big freeze in five hundred years’ time
? No land life form surviving that was bigger than a cockroach?’

  ‘No one bothered about that?’ said Ridcully.

  ‘Not until it was too late, sir. In that world as we left it, the first humans walked on the Moon less than seventy years after they flew at all.’

  Ponder looked at their blank faces.

  ‘Which was quite an achievement,’ he said.

  ‘Why? We’ve done that,’ said the Dean.

  Ponder sighed. ‘Things are different on a globe, sir. There are no broomsticks, no magic carpets, and going to the Moon is not just a case of pushing off over the edge and trying to avoid the Turtle on the way down.’

  ‘How did they do it, then?’ said the Dean.

  ‘Using rockets, sir.’

  ‘The things that go up and explode with lots of coloured lights?’

  ‘Initially, sir, but fortunately they found out how to stop them doing that. Next slide, please …’ A picture that might have been a pair of old-fashioned pantaloons appeared on the screen. ‘Ah, this is our old friend, the Trousers of Time. We all know this. It’s what you get when history goes two ways. What we have to do now is find out why they split. That means I shall have to—’

  ‘Are we near the point where you mention quantum?’ said Ridcully, quickly.

  ‘I’m afraid it is looming, sir, yes.’

  Ridcully stood up, gathering his robes about him. ‘Ah. I think I heard the gong for dinner, gentlemen. Just as well, really.’

  The moon rose. At midnight, Ponder Stibbons read what Hex had written, wandered across the dewy lawn to the Library, woke the Librarian, and asked for a copy of a book called The Origin of Species.