A Little History of Philosophy (Little Histories)

by Nigel Warburton

Wisdom for Socrates was not knowing lots of facts, or knowing how to do something. It meant understanding the true nature of our existence, including the limits of what we can know. Philosophers today are doing more or less what Socrates was doing: asking tough questions, looking at reasons and evidence, struggling to answer some of the most important questions we can ask ourselves about the nature of reality and how we should live. Unlike Socrates, though, modern philosophers have the benefit of nearly two and a half thousand years of philosophical thinking to build on. This book examines ideas of some of the key thinkers writing in this tradition of Western thought, a tradition that Socrates started.

Think of all the circles that you have seen in your life. Was any one of them a perfect circle? No. Not one of them was absolutely perfect. In a perfect circle every point on its circumference is exactly the same distance from the centre point. Real circles never quite achieve this. But you understood what I meant when I used the words ‘perfect circle’. So what is that perfect circle? Plato would say that the idea of a perfect circle is the Form of a circle. If you want to understand what a circle is, you should focus on the Form of the circle, not actual circles that you can draw and experience through your visual sense, all of which are imperfect in some way. Similarly, Plato thought, if you want to understand what goodness is, then you need to concentrate on the Form of goodness, not on particular examples of it that you witness. Philosophers are the people who are best suited to thinking about the Forms in this abstract way; ordinary people get led astray by the world as they grasp it through their senses. Because philosophers are good at thinking about reality, Plato believed they should be in charge and have all the political power. In The Republic, his most famous work, he described an imaginary perfect society. Philosophers would be at the top and would get a special education; but they would sacrifice their own pleasures for the sake of the citizens they ruled. Beneath them would be soldiers who were trained to defend the country, and beneath them would be the wor...

Unfortunately his model of society was profoundly anti-democratic, and would keep the people under control by a combination of lies and force. He would have banned most art, on the grounds that he thought it gave false representations of reality. Painters paint appearances, but appearances are deceptive about the Forms. Every aspect of life in Plato's ideal republic would be strictly controlled from above. It's what we would now call a totalitarian state. Plato thought that letting the people vote was like letting the passengers steer a ship – far better to let people who knew what they were doing take charge.

Aristotle was Plato's student, and Plato had been Socrates'. So these three great thinkers form a chain: Socrates–Plato–Aristotle. This is often the way. Geniuses don't usually emerge from nowhere. Most of them have had an inspirational teacher. But the ideas of these three are very different from each other. They didn't simply parrot what they had been taught. Each had an original approach. Put simply, Socrates was a great talker, Plato was a superb writer, and Aristotle was interested in everything. Socrates and Plato thought of the world we see as a pale reflection of true reality that could only be reached by abstract philosophical thought; Aristotle, in contrast, was fascinated by the details of everything around him.

Born in Macedonia in 384 BC, after studying with Plato, travelling, and working as a tutor to Alexander the Great, Aristotle set up his own school in Athens called the Lyceum. This was one of the most famous centres of learning of the Ancient World, a bit like a modern university.

No one knows anything – and even that's not certain. You shouldn't rely on what you believe to be true. You might be mistaken. Everything can be questioned, everything doubted. The best option, then, is to keep an open mind. Don't commit, and you won't be disappointed. That was the main teaching of Scepticism, a philosophy that was popular for several hundred years in Ancient Greece and later in Rome.

Whether or not you can imagine your own death, it seems quite natural to be at least a bit afraid of not existing. Who wouldn't fear their own death? If there's anything we should be anxious about, it's surely that. It seems perfectly reasonable to worry about not existing even if that will happen many years from now. It's instinctive. Very few people alive have never thought deeply about this. The Ancient Greek philosopher Epicurus (341–270 BC) argued that fear of death was a waste of time and based on bad logic. It was a state of mind to be overcome. If you think clearly about it, death shouldn't be frightening at all. Once you get your thinking straight you'll enjoy your time here much more – which for Epicurus was extremely important. The point of philosophy, he believed, was to make your life go better, to help you find happiness. Some people believe that it is morbid to dwell on your own death, but for Epicurus it was a way of making living more intense.

Eliminating suffering from your life and increasing happiness will make it go better. The best way to live, then, was this: have a very simple lifestyle, be kind to those around you, and surround yourself with friends. That way you'll be able to satisfy most of your desires. You won't be left wanting something you can't get. It's no good having a desperate urge to own a mansion if you won't ever have the money to buy one. Don't spend your whole life working in order to get something that is probably beyond your reach anyway. It's far better to live in a simple way. If your desires are simple they are easy to satisfy and you will have the time and energy to enjoy the things that matter. That was his recipe for happiness, and it makes a lot of sense.

Think about the time before your birth. There was all that time that you didn't exist. Not just the weeks when you were in your mother's womb when you might have been born early, or even the point before you were conceived but were just a possibility for your parents, but rather the trillions of years before you came along. We don't usually worry about not existing for all those millennia before our birth. Why should anyone care about all that time that they didn't exist? But then, if that's true, why should we care so much about all those aeons of non-existence after death? Our thought is asymmetrical.

The name ‘Stoic’ came from the Stoa, which was a painted porch in Athens where these philosophers used to meet. One of the first was Zeno of Citium (334–262 BC). Early Greek Stoics had views on a wide range of philosophical problems about reality, logic and ethics. But they were most famous for their views on mental control. Their basic idea was that we should only worry about things we can change. We shouldn't get worked up about anything else. Like the Sceptics, they aimed for a calm state of mind. Even when facing tragic events, such as the death of a loved one, the Stoic should remain unmoved. Our attitude to what happens is within our control even though what happens often isn't. At the heart of Stoicism was the idea that we are responsible for what we feel and think. We can choose our response to good and bad luck. Some people think of their emotions as like the weather. The Stoics, in contrast, thought that what we feel about a situation or event is a matter of choice.

So God is powerful enough to prevent all evil. But the fact that evil exists is still not directly due to God. Moral evil is a result of our choices. Augustine believed that it was also partly a result of Adam and Eve's choices. Like many Christians of his time, he was convinced that things went terribly wrong in the Garden of Eden as described in the first book of the Bible, Genesis. When Eve and then Adam ate from the Tree of Knowledge and so betrayed God, they brought sin into the world. This sin, called Original Sin, was not just something that affected their lives. Absolutely every human being pays the price. Augustine believed that Original Sin gets passed on to each new generation by the act of sexual reproduction. Even a child from its earliest moments bears traces of this sin. Original Sin makes us more likely to sin ourselves.

The rest of the book is their conversation, which is all about luck and God. It is written partly in prose and partly in poetry. The woman, Philosophy, gives him advice. She tells Boethius that luck always changes, and that he shouldn't be surprised by this. That's the nature of luck. It is fickle. The wheel of Fortune turns. Sometimes you are at the top; sometimes you are at the bottom. A wealthy king can find himself in poverty in a day. Boethius should realize that's just the way it is. Luck is random. There is no guarantee that because you are lucky today you will be lucky tomorrow. Mortals, Philosophy explains, are foolish to let their happiness depend on something so changeable. True happiness can only come from inside, from the things that human beings can control, not from anything that bad luck can destroy.

The message is that riches, power and honour are worthless since they can come and go. No one should base their happiness on such fragile foundations. Happiness has to come from something that is more solid, something that can't be taken away.

Anselm's argument, which he included in his book Proslogion, starts from the uncontroversial claim that God is that being ‘than which nothing greater can be conceived’. This is just another way of saying God is the greatest being imaginable: greatest in power, in goodness and in knowledge. Nothing greater can be imagined – or that thing would be God. God is the supreme being. This definition of God doesn't seem controversial: Boethius (see Chapter 7) defined God in a similar way, for example. In our minds, we can clearly have an idea of God. That too is uncontroversial. But then Anselm points out that a God that only existed in our minds but not in reality wouldn't be the greatest being conceivable. One that actually existed would certainly be greater. This God could conceivably exist – even atheists usually accept that. But an imagined God cannot be greater than an existing one. So, Anselm concluded, God must exist. It follows logically from the definition of God. If Anselm is right, we can be certain that God exists simply from the fact that we have an idea of God. This is an a priori argument, one that doesn't rely on any observation about the world to reach its conclusions. It is a logical argument that, from an uncontroversial starting point, seems to prove that God exists.

Two hundred years later in a short section in a very long book called Summa Theologica, another Italian saint, Thomas Aquinas (1225–74), outlined five arguments, the Five Ways that were meant to demonstrate that God exists. These Five Ways are now much better known than any other part of the book. The second of these was the First Cause Argument, an argument which, like much of Aquinas' philosophy, was based on one that Aristotle had used much earlier. Like Anselm, Aquinas wanted to use reason to provide proof for God's existence. The First Cause Argument takes as its starting point the existence of the cosmos – everything that there is. Look around you. Where did everything come from? The simple answer is that each thing that exists has a cause of some kind that brought it into being and made it as it is. Take a football. That is the product of many causes – of people designing and making it, of the causes that produced the raw materials, and so on. But what caused the raw materials to exist? And what caused those causes? You can go back and trace that. And back and back. But does that chain of causes and effects go on back for ever?

But Aquinas thinks that logically there must at some point have been something that set everything going in this chain of causes and effects. If he's right about that, there must have been something that wasn't itself caused that began the series of cause and effect which has brought us to where we are now: an uncaused cause. This first cause, he declared, must have been God. God is the uncaused cause of everything that is.

So what exactly did Machiavelli advise and why has this so shocked most of his readers? His key idea was that a prince needed to have what he called virtù. This is the Italian word for ‘manliness’ or valour. What does that mean? Machiavelli believed that success depends quite a lot on good luck. Half of what happens to us is down to chance and half is a result of our choices, he thought.

Machiavelli stresses that it's better as a leader to be feared than to be loved. Ideally you would be both loved and feared, but that's hard to achieve. If you rely on your people loving you, then you risk them abandoning you when times get tough. If they fear you, they will be too scared to betray you. This is part of his cynicism, his low view of human nature. He thought that human beings were unreliable, greedy and dishonest. If you are to be a successful ruler, then you need to know this. It's dangerous to trust anyone to keep their promises unless they are terrified of the consequences of not keeping them.

Descartes sets out in his quest for certainty by thinking first about the evidence that comes through the senses: seeing, touching, smelling, tasting and hearing. Can we trust our senses? Not really, he concluded. The senses sometimes trick us. We make mistakes. Think about what you see. Is your sight reliable about everything? Should you always believe your eyes? A straight stick put in water seems bent if you look at it from the side. A square tower in the distance might look round. We all occasionally make mistakes about what we see. And, Descartes points out, it would be unwise to trust something that has tricked you in the past. So he rejects the senses as a possible source of certainty. He can never be sure that his senses aren't tricking him.

The next move he made led to one of the best-known lines in philosophy, though many more people know the quotation than understand what it means. Descartes saw that even if the demon existed and was tricking him, there must be something that the demon was tricking. As long as he was having a thought at all, he, Descartes, must exist. The demon couldn't make him believe that he existed if he didn't. That's because something that doesn't exist can't have thoughts. ‘I think, therefore I am’ (cogito ergo sum in Latin) was Descartes' conclusion. I'm thinking, so I must exist. Try it for yourself. As long as you have some thought or sensation, it is impossible to doubt that you exist. What you are is another question – you can doubt whether you have a body, or the body that you can see and touch. But you can't doubt that you exist as some kind of thinking thing.

he convinced himself that the idea of God proves God's existence – God wouldn't be perfect unless he was good and existed, just as a triangle wouldn't be a triangle without interior angles adding up to 180 degrees. Another of his arguments, the Trademark Argument, suggested that we know God exists because he has left an idea implanted in our minds – we wouldn't have an idea of God if God didn't exist. Once he was certain that God existed, the constructive phase of Descartes' thought became much easier. A good God wouldn't deceive humanity about the most basic matters. So, Descartes concluded, the world must be more or less as we experience it. When we have clear and distinct perceptions these are reliable. His conclusion: the world exists, and is more or less as it appears, even though we sometimes make mistakes about what we perceive. Some philosophers, however, believe this was wishful thinking, and that his evil demon might just as easily have deceived him about God's existence as about the thought that 2 + 3 = 5. Without the certainty of a good God's existence, Descartes would not have been able to move beyond his knowledge that he was a thinking thing. Descartes believed that he had shown a way out of complete scepticism; but his critics are still sceptical about this.

Spinoza did not just admire geometry; he wrote philosophy as if it were geometry. The ‘proofs’ in his book Ethics look like geometrical proofs and include axioms and definitions. They are supposed to have the same relentless logic as geometry. But instead of dealing with topics like the angles of triangles and the circumferences of circles, they are about God, nature, freedom and emotion. He felt that these subjects could be analysed and reasoned about in just the same way that we can reason about triangles, circles and squares. He even ends sections with ‘QED’ which is short for quod erat demonstrandum, a Latin phrase meaning ‘which was to be proved’ that appears in geometry textbooks. There is, he believed, an underlying structural logic to the world and our place in it that reason can reveal. Nothing is as it is by chance, there is a purpose and principle to it all. Everything fits together in one huge system and the best way to understand this is by the power of thought. This approach to philosophy, emphasizing reason rather than experiment and observation, is often labelled Rationalism.

Locke, like many philosophers, had wide interests. He was enthusiastic about the scientific discoveries of his friends Robert Boyle and Isaac Newton, was involved in the politics of his day and also wrote about education. In the aftermath of the English Civil War, he fled to the Netherlands when accused of plotting to murder the newly restored king, Charles II. From there he championed religious toleration, arguing that it was absurd to try to force people to change their religious beliefs through torture. His view that we have a God-given right to life, freedom, happiness and property influenced the founding fathers who wrote the United States Constitution.

Unlike Locke he thought that we do perceive the world directly. That is because the world consists of nothing but ideas. The whole of experience is all that there is. In other words, the world and everything in it only exist in people's minds. Everything you experience and think about – a chair or a table, the number 3, and so on – for Berkeley only exists in the mind. An object is just a collection of ideas that you and other people have of it. It doesn't have any existence beyond that. Without someone to see or hear them, objects simply stop existing, because objects aren't anything over and above the ideas that people (and God) have of them. Berkeley summed up this strange view in Latin as ‘Esse est percipi’ – to be (or exist) is to be perceived.

Berkeley didn't spend every hour of his day defending his immaterialism. There was much more to his life than that. He was a sociable and likeable man, and his friends included the author of Gulliver's Travels, Jonathan Swift. In later life Berkeley hatched an ambitious plan to set up a college on the island of Bermuda and managed to raise quite a lot of money to do this. Unfortunately the plan failed, partly because he hadn't realized how far from the mainland Bermuda was and how difficult it was to get supplies there. He did, however, after his death, have a West Coast university named after him – Berkeley in California. That came from a poem he wrote about America which included the line ‘Westward the course of empire takes its way’, a line that appealed to one of the university's founders.

François-Marie Arouet (1694–1778), better known as Voltaire, didn't see it this way. He took no comfort at all from this ‘proof’ that everything is going well. He was deeply suspicious of philosophical systems and the kind of thinkers who believe they have all the answers. This French playwright, satirist, fiction writer and thinker was well known throughout Europe for his outspoken views. The most famous sculpture of him, by Jean-Antoine Houdon, captures the tight-lipped smile and laughter lines of this witty, brave man. A champion of free speech and religious toleration, he was a controversial figure. He is, for instance, supposed to have declared, ‘I hate what you say, but will defend to the death your right to say it’, a powerful defence of the idea that even views that you despise deserve to be heard.

He is best known today, though, as the author of Candide (1759). In this short philosophical novel he completely undermined the kind of optimism about humanity and the universe that Pope and Leibniz had expressed, and he did it in such an entertaining way that the book became an instant bestseller. Wisely Voltaire left his name off the title page, otherwise its publication would have landed him in prison again for making fun of religious beliefs. Candide is the central character. His name suggests innocence and purity. At the start of the book, he is a young servant who falls hopelessly in love with his master's daughter, Cunégonde, but is chased out of her father's castle when he is caught in a compromising position with her. From then on, in a fast-moving and often fantastical tale, he travels through real and imaginary countries with his philosophy tutor Dr Pangloss, until he finally meets up with his lost love Cunégonde again, though by now she is old and ugly. In a series of comical episodes Candide and Pangloss witness terrible events and encounter a range of characters along the way, all of whom have themselves suffered terrible misfortunes. Voltaire uses the philosophy tutor, Pangloss, to spout a caricatured version of Leibniz's philosophy, which the writer then pokes fun at. Whatever happens, whether it is a natural disaster, torture, war, rape, religious persecution or slavery, Pangloss treats it as further confirmation that they live in the best of all possible ...

In 1755 one of the worst natural disasters of the eighteenth century occurred: the Lisbon earthquake that killed more than 20,000 people. This Portuguese city was devastated not just by the earthquake, but also by the tsunami that followed, and then by fires that raged for days. The suffering and loss of life shook Voltaire's belief in God. He couldn't understand how an event like this could be part of a larger plan. The scale of suffering didn't make any sense to him. Why would a good God allow this to happen? Nor could he see why Lisbon was the target. Why there and not somewhere else? In a key episode in Candide, Voltaire used this real tragedy to help make his case against the optimists. The travellers are shipwrecked near Lisbon in a storm that kills almost everyone else on board their ship. The only one of the crew to survive was a sailor who had apparently deliberately drowned one of their friends. But despite the obvious lack of justice in this, Pangloss still sees everything that happens through the filter of his philosophical optimism. Arriving in Lisbon just after the earthquake has devastated the city and left tens of thousands dead or dying around him, Pangloss continues, absurdly, to maintain that all is well. In the rest of the book things get even worse for Pangloss – he is hanged, dissected alive, beaten and made to row a galley.

Voltaire was unusual amongst philosophers in being rich. As a young man he had been part of a syndicate that had found a flaw in the state lottery and had bought thousands of winning tickets. He invested wisely and became even richer. This gave him the financial freedom to champion the causes he believed in. Rooting out injustice was his passion. One of his most impressive acts was to defend the reputation of Jean Calas, who had been tortured and executed for supposedly murdering his own son. Calas was clearly innocent: his son had committed suicide, but the court had ignored the evidence. Voltaire managed to get the judgment overturned. There was no chance of consolation for poor Jean Calas, who had protested his innocence to his last breath; but at least his ‘accomplices’ were freed. This is what ‘cultivating our garden’ meant in practice for Voltaire. From the way Voltaire mocks Pangloss' ‘proof’ that God has produced the best of all possible worlds, you might assume that Candide's author was an atheist. In fact, although he had no time for organized religion, he was a deist, someone who believes that there is visible evidence of God's existence and design to be found in nature. For him, looking up at the night sky was all it took to prove that a Creator exists. David Hume was highly sceptical of this idea. His criticisms of this style of reasoning are devastating.

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.

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.

heads was closer in spirit to Machiavelli's thinking than to his. According to Rousseau, human beings are naturally good. Left to our own devices, living in a forest, we wouldn't cause many problems. But take us out of this state of nature and put us in cities and things start to go wrong. We become obsessed with trying to dominate other people, and with getting other people's attention. This competitive approach to life has terrible psychological effects and the invention of money just makes it all far worse. Envy and greed were the result of living together in cities. In the wild, individual ‘noble savages’ would be healthy, strong and, above all, free,

What everyone says they want if you ask them is what Rousseau would call the Will of All. In contrast, the General Will is what they ought to want, what would be good for the whole community, not just for each person within it thinking selfishly. When working out what the General Will is we have to ignore self-interest and focus on the good of the whole society, the common good. If we accept that many services, such as the upkeep of roads, need to be paid for from taxation then it is good for the whole community that taxes are high enough to make this possible. If they are too low, then the whole society will suffer. That then is the General Will: that taxes should be high enough to provide a good level of services.

Kant's own mind was very ordered and logical. So was his life. He never married and he imposed a strict pattern to each day. In order not to waste any time, he had his servant wake him at 5 a.m. He would then drink some tea, smoke a pipe, and begin work. He was extremely productive, writing numerous books and essays. Then he would lecture at the university. In the afternoon, he would go for a walk at 4.30 – exactly the same time each day – up and down his street precisely eight times. In fact people who lived in his home town of Königsberg (now Kaliningrad) used to set their watches by his walk. Like most philosophers, he spent his time trying to understand our relation to reality. That, in essence, is what metaphysics is about, and Kant was one of the greatest metaphysicians to have lived. His particular interest was in the limits of thought, the limits of what we can know and understand. This was an obsession for him. In his most famous book The Critique of Pure Reason (1781), he explored these limits, pushing right to the boundaries of what makes sense.

Always ask the question: ‘What if everyone did that?’ Don't make a special case for yourself. Kant thought what this meant in practice was that you shouldn't use other people but should treat them with respect, recognizing other people's autonomy, their capacity as individuals to make reasoned decisions for themselves. This reverence for the dignity and worth of individual human beings is at the core of modern human rights theory. It is Kant's great contribution to moral philosophy.

Some of Bentham's other ideas were more practical. Take his design for a circular prison, the Panopticon. He described it as ‘a machine for grinding rogues honest’. A watchtower in the middle allows a few guards to keep an eye on a large number of prisoners without them knowing whether or not they're being watched. This design principle is used in some modern prisons and even several libraries. It was one of his many projects for social reform. But far more important and influential than this was Bentham's theory about how we should live. Known as utilitarianism or the Greatest Happiness Principle, this is the idea that the right thing to do is whatever will produce the most happiness. Although not the first person to suggest this approach to morality (Francis Hutcheson, for instance, had already done so), Bentham was the first to explain in detail how it might be put into practice. He wanted to reform the laws of England so that they were more likely to bring about greater happiness.

The Felicific Calculus was the name he gave to his method for calculating happiness. First, work out how much pleasure a particular action will bring about. Take into account how long the pleasure will last, how intense it is, how likely it is that it will give rise to further pleasures. Then subtract any units of pain that might be caused by your action. What you are left with is the happiness value of the action. Bentham called this its ‘utility’, meaning usefulness, because the more pleasure an action brings about the more useful it is to society. That's why the theory is known as utilitarianism. Compare the utility of an action with the scores for other possible actions and choose the one that brings about most happiness. Simple.

Utilitarianism was a radical theory to put forward at the end of the eighteenth century. One reason was that in calculating happiness everyone's happiness was equal; in Bentham's words, ‘Everybody to count for one, nobody to count for more than one’. No one gets special treatment. The pleasure of an aristocrat counted no more than the pleasure of a poor worker. That was not how society was ordered then. Aristocrats had a very great influence over how land was used, and many even had a hereditary right to sit in the House of Lords and decide on the laws of England. Not surprisingly, some felt uncomfortable with Bentham's stress on equality. Perhaps even more radical for the time was his belief that animals' happiness was relevant. Because they are capable of pleasure and pain, animals were part of his happiness equation.

Life is painful and it would be better not to have been born. Few people have such a pessimistic outlook, but Arthur Schopenhauer (1788–1860) did. According to him, we are all caught up in a hopeless cycle of wanting things, getting them, and then wanting more things. It doesn't stop until we die. Whenever we seem to get what we want, we start wanting something else. You might think you would be content if you were a millionaire, but you wouldn't be for long. You'd want something you hadn't got. Human beings are like that. We're never satisfied, never stop craving for more than we have. It's all very depressing.

No other philosopher has given such a central place to the arts, so it is not surprising that Schopenhauer is popular with creative people of various kinds. Composers and musicians love him because he believed that music was the most important of all the arts. His ideas have also appealed to novelists including Leo Tolstoy, Marcel Proust, Thomas Mann and Thomas Hardy. Dylan Thomas even wrote a poem ‘The force that through the green fuse drives the flower’ which was inspired by Schopenhauer's description of the World as Will. Schopenhauer didn't just describe reality and our relation to it. He also had views about how we should live. Once you realize that we are all part of one energy force, and that individual people exist only at the level of the World as Representation, this should change what you do. For Schopenhauer, harming other people is a kind of self-injury. This is the foundation of all morality. If I kill you, I destroy a part of the life force that joins us all together. When someone harms another person it is like a snake biting its tail without knowing that it is sinking its fangs into its own flesh. So the basic morality that Schopenhauer taught was one of compassion. Properly understood, other people aren't external to me. I care what happens to you because in a way you are part of what we are all part of: the World as Will. That's Schopenhauer's official moral position. It is questionable, though, whether he achieved anything like this degree of concern fo...

Mill thought paternalism was fine when it was directed at children: children need to be protected from themselves and have their behaviour controlled in various ways. But paternalism towards adults in a civilized society was unacceptable. The only justification for it was when an adult risked harming someone else by their actions or if they had severe psychiatric problems. Mill's message was simple. It is known as the Harm Principle. Every adult should be free to live as he or she pleases as long as no one else is harmed in the process. This was a challenging idea in Victorian England when many people assumed that part of

role of government was to impose good moral values on the people. Mill disagreed.

As well as freedom in how to live, Mill thought it was vital that everyone was given freedom to think and speak as they liked. Open discussion was of great benefit to society, he felt, because it forced people to think hard about what they believed. If you don't have your views challenged by people with opposing views, then you will probably end up holding them as ‘dead dogmas’, prejudices that you can't really defend. He argued for free speech up to the point at which it incited violence. A journalist, he believed, should be free to write an editorial in which he declared that ‘corn-dealers are starvers of the poor’, but if he waved a placard with the same words on it while standing on the steps of a corn-dealer's house in front of an angry mob, that would be an incitement to violence and so forbidden by Mill's Harm Principle.

in the Communist Manifesto of 1848, which he wrote with Engels, he called upon workers of the world to unite and overthrow capitalism. Echoing the opening lines of Jean-Jacques Rousseau's Social Contract (see Chapter 18), they declared that the workers had nothing to lose but their chains. Marx's ideas about history were influenced by Hegel (the subject of Chapter 22). Hegel, as we have seen, declared that there is an underlying structure to everything, and that we are gradually progressing to a world that will somehow be conscious of itself. Marx took from Hegel the sense that progress is inevitable, and that history has a pattern and is not just one thing after another. But in Marx's version, progress occurs because of the underlying economic forces. In place of the class struggle Marx and Engels promised a world in which no one would own land, where there was no inheritance, where education was free, and where public factories provided for everyone. There would be no need for religion or morality either. Religion, he famously declared, was ‘the opium of the people’: it was like a drug keeping them in a sleepy state so they didn't realize their true oppressed condition. In the new world after the revolution human beings would achieve their humanity. Their work would be meaningful and they would co-operate in ways that benefited everyone. Revolution was the way to achieve all this – and this meant violence, since the rich were unlikely to give up their wealth without a st...

Pragmatism is a philosophical approach that became popular in the United States in the late nineteenth century. It started with the American philosopher and scientist C.S. Peirce (pronounced ‘purse’), who wanted to make philosophy more scientific than it had been. Peirce (1839–1914) believed that for a statement to be true there had to be some possible experiment or observation to support it.

He declared that ‘truth is what your contemporaries let you get away with’ and that no period of history gets reality more nearly right than any other. When people describe the world, Rorty believed, they are like literary critics giving an interpretation of a Shakespeare play: there's no single ‘correct’ way of reading it that we should all agree on. Different people at different times interpret the text differently. Rorty simply rejected the idea that any one view is correct for all time. Or at least that's my interpretation of his work. Rorty presumably believed that there was no correct interpretation of it in the same way that there's no ‘right’ answer about whether the hunter was circling the squirrel as it scrambled round the tree.

Nietzsche was a remarkable man. Appointed as a professor at the University of Basel at the very young age of 24, he looked set for a distinguished academic career. But this eccentric and original thinker didn't fit in or conform, and seemed to enjoy making life hard for himself. He eventually left the university in 1879, partly because of ill health, and travelled in Italy, France and Switzerland, writing books that hardly anyone read at the time, but which are now famous as works of both philosophy and literature. His psychological health declined and he spent much of his later life in an asylum.

If God is dead, what comes next? That's the question Nietzsche asked himself. His answer was that it left us without a basis for morality. Our ideas of right and wrong and good and evil make sense in a world where there is a God. They don't in a godless one. Take away God and you take away the possibility of clear guidelines about how we should live, which things to value. That's a tough message,

Perhaps influenced by his understanding of Charles Darwin's theory of evolution, he saw the Übermensch as the next step in humanity's development. This is a bit worrying, partly because it seems to support those who see themselves as heroic and want to have their way without consideration of other people's interests. Worse still, it was an idea that the Nazis took from Nietzsche's work and used to support their warped views about a master race, though most scholars argue that they distorted what Nietzsche actually wrote. Nietzsche was unfortunate in that his sister Elisabeth controlled what happened to his work after he lost his sanity and for thirty-five years after his death. She was a German nationalist of the very worst kind and an anti-Semite. She went through her brother's notebooks, picking out the lines she agreed with and leaving out anything that criticized Germany or didn't support her racist viewpoint. Her cut-and-paste version of Nietzsche's ideas, published as The Will to Power, turned his writing into propaganda for Nazism, and Nietzsche became an approved author in the Third Reich. It is highly unlikely that, had he lived longer, he would have had anything to do with it. Yet it is undeniable that there are plenty of lines in his work that defend the right of the strong to destroy the weak. It is no surprise, he tells us, that lambs hate birds of prey. But that doesn't mean we should despise the birds of prey for carrying off and devouring the lambs.

Bertrand's non-religious ‘godfather’ was the philosopher John Stuart Mill (the subject of Chapter 24). Sadly, he never got to know him as Mill died when Russell was still a toddler. But he was still a huge influence on Russell's development. Reading Mill's Autobiography (1873) was what led Russell to reject God. He had previously believed the First Cause Argument. This is the argument, used by Thomas Aquinas amongst others, that everything must have a cause; and the cause of everything, the very first cause in the chain of cause and effect, must be God. But Mill asked the question ‘What caused God?’ and Russell saw the logical problem for the First Cause Argument. If there is one thing that doesn't have a cause then it can't be true that ‘Everything has a cause’. It made more sense to Russell to think that even God had a cause rather than believe that something could just exist without being caused by anything else.