فصل 17

chapter 17

The Imaginary Watchmaker

David Hume

Take a look in the mirror at one of your eyes. It has a lens that focuses the image, an iris that adapts to changing light, and eyelids and eyelashes to protect it. If you look to one side, the eyeball swivels in its socket. It’s also quite beautiful. How did that happen? It’s an amazing bit of engineering. How could an eye have turned out this way just by chance?

Imagine stumbling through a jungle on a deserted island, and coming to a clearing. You clamber over the tumbled remains of a palace with walls, stairs, pathways and courtyards. You know it couldn’t have got there by chance. Someone must have designed it, some kind of architect. If you find a watch when you are out for a walk it is quite reasonable to assume that it has been made by a watchmaker, and that it was designed for a purpose: to tell the time. Those tiny cogwheels didn’t just fall into place by themselves. Someone must have thought it all through. All these examples seem to point to the same thing: objects that look as if they have been designed almost certainly have been.

Well then, think of nature: trees, flowers, mammals, birds, reptiles, insects, even amoebae. These things also look as if they have been designed. Living organisms are much more complicated than any watch. Mammals have complex nerve systems, blood pumping round their body, and are usually very well suited to the places they inhabit. So surely an incredibly powerful and intelligent Creator must have made them. That Creator – a Divine Watchmaker or Divine Architect – must have been God. Or that’s what many people thought in the eighteenth century when David Hume was writing – and some still do today.

This argument for the existence of God is often known as the Design Argument. New discoveries in science in the seventeenth and eighteenth centuries seemed to support it. Microscopes revealed the complexity of tiny pond animals; telescopes showed the beauty and regularity of the solar system and the Milky Way. These too seemed to have been put together with great precision.

The Scottish philosopher David Hume (1711–76) wasn’t convinced. Influenced by Locke, he set out to explain the nature of humanity and our place in the universe by considering how we acquire knowledge and the limits of what we can learn by using reason. Like Locke, he believed that our knowledge comes from observation and experience, so he was particularly interested in an argument for God’s existence that began with observation of some aspects of the world.

He believed the Design Argument was based on bad logic. His Enquiry Concerning Human Understanding (1748) included a chapter attacking the idea that we can prove God’s existence in this way. That chapter and one arguing that it was never reasonable to believe eyewitness reports of miracles were extremely controversial. At the time in Britain it was difficult to be openly against religious beliefs. This meant Hume never got a job at a university despite being one of the great thinkers of his time. His friends gave him good advice when they told him not to allow publication of his most powerful attack on the usual arguments for God’s existence, his Dialogues Concerning Natural Religion (1779), until after his death.

Does the Design Argument prove the existence of God? Hume thought it didn’t. The argument does not provide enough evidence to conclude that an all-powerful, all-knowing and all-good being must exist. Most of Hume’s philosophy concentrated on the kind of evidence we can give in support of our beliefs. The Design Argument is based on the fact that the world appears to be designed. But, Hume argued, just because it looks designed, it doesn’t follow that it really was designed; nor does it follow that God was the designer. How did he arrive at that conclusion?

Imagine an old-fashioned set of weighing scales partly behind a screen. You can only see one of the two pans of the scales. If you see that pan going up, all you can know is that whatever is in the other pan is heavier than the one you can see. You can’t tell what colour it is, whether it is cube-shaped or spherical, whether it has words written on it, or is covered in fur, or anything else.

In this example we’re thinking about causes and effects. In answer to the question ‘What caused the pan to move upwards?’ all you can answer is, ‘The cause was something heavier in the other pan.’ You see the effect – the pan going up – and try to work out the cause from that. But without further evidence there’s not a lot more you can say. Anything you do say is pure guesswork and we have no way of telling whether it is true or not if we can’t look behind the screen. Hume thought we are in a similar situation with the world around us. We see the effects of various causes, and try to work out the most likely explanation of these effects. We see a human eye, a tree, a mountain, and they might well appear to be designed. But what can we say about their probable designer? The eye looks as if an eye-maker has thought about how best to make it work. It doesn’t follow from this, though, that the eye-maker was God. Why not?

God is usually thought of as having the three special powers already mentioned: he is all-powerful, all-knowing and all-good. Even if you reach the conclusion that something very powerful made the human eye, you don’t have evidence to say that it was all-powerful. The eye has some flaws. Things go wrong: many people need spectacles to see properly, for example. Would an all-powerful, all-knowing and all-good God have designed the eye just this way? Possibly. But the evidence we get from looking at the eye doesn’t show this. At best it shows that something highly intelligent and very powerful and skilful made it.

But does it even show that? There are other possible explanations. How do we know the eye wasn’t designed by a team of lesser gods all working together? Most complex machinery is put together by a team of people; why doesn’t the same hold for eyes and other natural objects, assuming they are put together at all? Most buildings are built by a team of builders; why should an eye be different? Or perhaps the eye was made by a very old god who has since died. Or a very young god who was still learning how to design perfect eyes. Because we don’t have evidence to decide between these different stories, we can’t be sure just from looking at the eye – an apparently designed object – that it was definitely made by a single living God with the traditional powers. If you start thinking clearly in this area, Hume believed, you will be very limited in the conclusions you can draw.

Another argument that Hume attacked was the Argument from Miracles. Most religions claim that miracles have happened. People are raised from the dead, walk on water, or make unexpected recoveries from illness; statues talk or cry, the list goes on. But should we believe that miracles have happened just because other people tell us they have? Hume thought not. He was deeply sceptical about that idea. If someone tells you that a man has miraculously recovered from an illness, what does that mean? For something to be a miracle, Hume thought, it had to defy a law of nature. A law of nature was something like ‘No one dies and comes back to life again’ or ‘Statues never talk’ or ‘No one can walk on water’. There is a huge amount of evidence that these laws of nature hold. But if someone witnesses a miracle, why shouldn’t we believe them? Think about what you would say if your friend came running into the room now and told you that she had seen someone walking on water.

Hume’s view was that there were always more plausible explanations of what was going on. If your friend tells you that she saw someone walking on water, it is always more likely that she is either deceiving you, or has been mistaken herself, than that she has witnessed a genuine miracle. We know that some people delight in being the centre of attention and are prepared to lie to get there. So that’s one possible explanation. But we also know that all of us can get things wrong. We make mistakes all the time about what we see and hear. Often we want to believe that we have seen something unusual and so avoid the more obvious explanation. Even today there are many people who jump to the conclusion that every unexplained sound late at night is the result of supernatural activity – ghosts moving about – rather than being due to more ordinary causes such as mice or the wind.

Although he regularly criticized the arguments used by religious believers, Hume never openly declared that he was an atheist. He may not have been. His published views could be read as claiming that there is a divine intelligence behind everything in the universe, it’s just that we can never say much about the qualities of that divine intelligence. Our powers of reason, when used logically, don’t tell us much at all about what qualities this ‘God’ must have. On the basis of this, some philosophers think he was an agnostic. But he probably was an atheist by the end of his life, even if he stopped short of that before then. When his friends came to visit him in Edinburgh in the summer of 1776 as he was dying he made clear that he wasn’t about to have a deathbed conversion. Far from it. James Boswell, a Christian, asked him whether he was worried about what would happen after he died. Hume told him he had absolutely no hope that he would survive death. He gave the answer that Epicurus might have given (see Chapter 4): he was, he said, no more worried about the time after his death than he was about the time he had not existed before his birth.

Hume had many brilliant contemporaries, many of whom he knew personally. One of them, Jean-Jacques Rousseau, made a significant impact on political philosophy.