Aristotle

Aristotle was born in Stagiros, Macedon, in 384BCE. His father was a court physician to King Amyntas of Macedon, but died when Aristotle was young. At that time, medicine was a secret craft passed down from father to son, so his father's early death drastically changed the course of Aristotle's life. He was brought up and educated by a guardian, who sent him at the age of seventeen to the centre of intellectual and artistic life, Athens. There he entered Plato's Academy (Plato was away in Syracuse at the time), where he stayed for about twenty years, first as student then as teacher.

When Plato died, the story becomes a little obscure. Aristotle left Athens, but it's not clear exactly why. It might have been because he was passed over as head of the Academy, or because of his philosophical differences with the new head, Speusippus, or because of his Macedonian antecedents. Macedon was unpopular at that time, because the new king, Philip, was rapidly expanding the borders of his kingdom, and Athenians felt threatened. Moreover, Aristotle wasn't simply tarred by the brush of geography; he was a childhood friend of Philip, and had retained his connections with the family.

Whatever the reason, Aristotle sailed for Assos in Asia Minor, where he lived for three years, developed his interest in anatomy and biology, and began work on his book the Politics. However, the Persians attacked and overran Assos in 345BCE, killing the king, and Aristotle left with his circle of philosophers, staying for a year in Mytilene on Lesbos (where he pursued his zoological investigations), before moving to Macedon, and is said to have became tutor to Philip's son, Alexander.

When Philip died and Alexander succeeded him, Aristotle returned to Athens. The Academy was flourishing under its new head, Xenocrates, and Aristotle founded his own school outside Athens, in a place called the Lyceum. He taught there for thirteen years, giving both public and private lectures. The Lyceum had a broader curriculum than the Academy, and a stronger emphasis on natural philosophy. With Alexander the Great's death in 323BCE came a change in the government of Athens, and a wave of anti-Macedonian feeling. Aristotle left Athens to live in a family house in Chalcis in Euboea; he died there the following year.

Aristotle's writings formed a huge and varied corpus, including dialogues, popular treatises, and serious works of scholarship; most of these have been lost, as has the vast collection of scientific and historical observational data that he built up himself and through his corres­pondents). What remains falls mainly into two (unclearly differentiated) categories: lecture notes worked up and published after his death, and work by later members of his school. It's for this reason that what we know of Aristotle's work is very unlike the golden prose so admired by his contemporaries. The content, however, more than makes up for any deficiencies in the style.

The surviving works fall into five main categories, usually ordered as they were in the first edition of Aristotle's work by his follower Andronicus of Rhodes (fl. 1st century BCE): the six logical works, which together are known as the Organon ("tool" or "instrument"); the three works on the physical sciences (including the Physics itself); the work devoted to "first philosophy", the most fundamental and abstract of studies, now known as the Metaphysics ("meta ta phusika": "after the physics"); six works in politics, ethics, and aesthetics, including most importantly the Nicomachean Ethics (named for his son by his second wife, Nicomachus); a large number of works on psychology and natural history, including On the Soul (often known by its Latin title, De Anima)

In many of these works, and in his teaching at the Lyceum, Aristotle was the first to divide the subjects in the way that we still do nearly 2,500 years later, as well as the first to treat them systematically and rationally. The major difference between him and Plato lay in their epistemology. Both valued and emphasised the rôle of reason, but Plato held that the most important truths, the objects of knowledge, must be attained through reason alone, while Aristotle took observation to be crucial; he held that both the world and the human mind were so structured as to make understanding possible. His scientific work was hugely important for the development of our knowledge of the world; it was, of course, full of errors, but his project of a systematic investigation into natural phenomena – especially the living world – marks the birth of empirical science.

Even restricting ourselves to the narrower modern notion of philosophy proper, his work and influence is too vast to cover in a short space. His concern with empirical observation wasn't restricted to sciences such as biology and astronomy, but extended to history, psychology, language, ethics, and politics. Ironically, though, his influence on mediaeval philosophy was so tremendous that it stifled empirical investigation (though not as completely as is sometimes thought). It wouldn't be too far-fetched to say that people lived in an Aristotelian world for nineteen centuries after Aristotle's death. Not only were Arab philosophers deeply influenced by him (and it's largely through them that his work survived the collapse of the Roman Empire), but Christian theology from the end of the twelfth century, and especially in the work of Thomas Aquinas and his successors, spent much time trying to adjust Christian teaching to fit in with Aristotelian theories (both Plato and Aristotle played such a central rôle in mediaeval theology that they were dubbed "Christians before Christ", and sometimes even given haloes in paintings).