Philosophy: History of Western Thought

1. What is philosophy? Like all other questions, the answer is open to debate ... luckily for philosophers, who've spent thousands of years arguing the toss. Best not to ask one of them, to be honest. Philosophers think about all sorts of stuff, including logic, metaphysics, politics, ethics, aesthetics.

2. Before the 4th century BC there was quite a bit of thinking going on, by the sophists and such like. But philosophy really began to kick ass with Greek clever-clogs Socrates, who said that virtue came with knowledge. Condemned to death for impiety, he killed himself by drinking hemlock.

3. Socrates died before writing any of his thoughts down, but we know quite a bit about him thanks to one of his students, Plato. He argued that there exist perfect forms of all things, and the world we know through our senses is a mere imitation of this.

4. One of Plato's students was Aristotle, who in turn went on to teach Alexander the Great, who went on to great things, specifically conquering the world. Aristotle invented logic, saying that since (i) every Greek is a person, and (ii) every person is mortal: then it follows that (iii) every Greek is mortal. Sounds logical. Aris is also cockney rhyming slang for the body part many people say philosophers talk out of.

5. The western world chewed on that for hundreds of years. Then came René Descartes (1596 - 1650), regarded as the founder of modern philosophy. Doubting the existence of the world around him, he realised that the only thing he could be sure of was that he was thinking. I think, therefore I am - that was one of his. But having proved his own existence, he got his knickers in a twist trying to prove that the rest of the universe was not a figment of his imagination.

6. John Locke (1632-1704) didn't get round to publishing anything on philosophy until he was 57. He neatly sidestepped awkward Cartesian problems of the relation between mind and body by focusing on ideas. Using our senses, we gain knowledge though experience. Well, duh.

7. Like Locke, Immanuel Kant (1724-1804) was an advocate of reason. Kant sought to prove that ethical conduct is also rational: in other words, being bad is stupid. So next time you feel tempted to park in a disabled car space or detonate a weapon of mass destruction, think on. Fact: throughout his life, Kant never ventured more than a few miles from his home in Germany.

8. Is it a bird? Is it a plane? No, it's bearded proto-Nazi Friedrich Nietzsche (1844-1900) who posited the idea of a superman. He also repudiated Christianity. Hitler was a big fan.

9. Ludwig Wittgenstein (1889-1951) wrote just one book, the snappily titled Tractatus Logico-Philosophicus, in which he argued that we each have a unique understanding of our common language, meaning that objective truths about the world are hard to establish. After his death, a collection of his students' lecture notes was published, which showed that he'd spent his life since the Tractatus rebutting his own arguments.

10. Although born in Austria, Wittgenstein adopted Britain as his home. Today Britain's most famous philosopher is rightwing cigarette salesman Roger Scruton, whose chief contribution to the sum of human knowledge is to argue that fox-hunting is great. Makes you think, doesn't it?

Jon Dennis has a II, ii in philosophy from Leicester University