Aristotle (Stagira, Macedonia, 384 BC – Chalicis, Euboea, Greece, 7 March 322 BC) was a Greek philosopher. He was one of the most important philosophers in the history of Western civilization.  Aristotle probably wrote many books, but very few of those books survive. Aristotle tutored Alexander the Great when Alexander was a child.

Life 
Aristotle's father was named Nicomachus. He was a soldier for King Amyntas of Macedonia.

At about the age of eighteen, Aristotle went to Athens to become a student of Plato at Plato's Academy. Aristotle remained at the academy until he was 27.  He left after Plato died in 347 BC. 

He then traveled with Xenocrates to Asia Minor. While in Asia, Aristotle traveled with Theophrastus to the island of Lesbos. They researched the botany and zoology of the island. 

In 343 B.C., Philip II of Macedon invited Aristotle to tutor his son Alexander the Great.  Aristotle was put in charge of the royal academy of Macedon. During that time, he did not only teach Alexander; he also taught two other future kings: Ptolemy and Cassander.

Aristotle encouraged Alexander to conquer lands to the east because he believed in ethnocentrism. (Ethnocentrism is the belief that one's own culture is better than all of the other cultures.)  Aristotle believed Greek culture was better than all of the other cultures. He encouraged Alexander to conquer Persia, which was an empire to the east, because he thought it would be better if the Greeks were in charge. One time, he advised Alexander to be 'a leader to the Greeks and a despot to the barbarians, to look after the former as after friends and relatives, and to deal with the latter as with beasts or plants'.p58

By 335 BC Aristotle returned to Athens. He started his own school there. It was called the Lyceum. Aristotle taught courses at the school for twelve years. 

During this time (335 to 323 B.C.), Aristotle probably wrote many of his works. Aristotle wrote many dialogues. Only parts of his dialogues survive. The works that have survived are torn and hard to read. They were probably lecture notes for his students. All of Aristotle's works are like an encyclopedia of everything that the Greeks knew. Some people think Aristotle was probably the last person to know everything there was to know about in his own time.

Near the end of Alexander's life, he began to think people might be trying to kill him. He threatened Aristotle in letters he wrote to him. Aristotle often said that he disliked that Alexander called himself a god. The king executed Aristotle's grandnephew Callisthenes as a traitor. Alexander died in Babylon in 323 B.C. without ever going back to Greece. When Alexander died, Athenians started to dislike Macedonians again and Aristotle left the city. He died in Euboea of natural causes that same year, 322 BC.

Philosophy 
The three greatest ancient Greek philosophers were Aristotle, Plato, and Socrates. Socrates taught Plato, then Plato taught Aristotle. These three thinkers turned early Greek philosophy into the beginnings of Western philosophy as it is today.

Plato's main ideas were that knowledge from the senses was always confused and not pure. True knowledge can be gotten from the thinking soul that turns away from the world. Only the soul can have knowledge of "Forms", the real way things are. The world is only a copy of these "Forms" and is not perfect.

Aristotle thought differently. He thought that knowledge from the senses was more important. These thoughts became some of the roots of the scientific method after hundreds of years. Most of the things Aristotle wrote that we still have today are notes from his speaking and teaching. Some of his important writings are Physics, Metaphysics, (Nicomachean) Ethics, Politics, De Anima (On the Soul), and Poetics.

He also had problems with the atomic theory. He did not believe in Democritus' theories about the atomic theory. He believed that all matter was continuous whereas Democritus stated the all matter was made up of tiny indivisible things called "atoms". Democritus was proved right by physicist John Dalton in 1804.

Logic 
Aristotle created a form of logic. His logic is called sentential logic because it uses sentences for the syllogism.

Aristotle's logic influenced the history of Western thought. It was Aristotle's logic which was copied and used in the Arabic and Latin mediaeval traditions. It was dominant for two and a half thousand years, until the late 19th century. Then modern logic was started by Gottlob Frege, Charles Sanders Peirce and others.

Biology 

Aristotle is the earliest natural historian whose work has survived in some detail. He certainly did research on the natural history of Lesbos, and the surrounding seas and neighbouring areas. The works History of Animals, Generation of Animals and Parts of Animals have observations and interpretations, along with some myths and mistakes.

The most striking passages are about the sea-life round Lesbos. As well as live observation, he got specimens from the catches of fishermen. His observations on catfish, electric fish (Torpedo) and angler-fish are detailed. His writing on cephalopods such as Octopus, Sepia (cuttlefish) and the paper nautilus (Argonauta argo) are accurate. His description of the hectocotyl arm, used in sexual reproduction, was widely disbelieved until its rediscovery in the 19th century. He separated the aquatic mammals from fish, and knew that sharks and rays were part of the group he called Selachē (Selachimorpha).

Another good example of his methods comes from the Generation of Animals in which Aristotle describes breaking open fertilized chicken eggs at intervals to observe when visible organs were generated.

He gave accurate descriptions of ruminants' four-chambered fore-stomachs, and of the ovoviviparous egg development of the houndshark Mustelus mustelus.

The works 
The works are traditionally listed in this sequence:
 Logic
 Categories (terms)
 On Interpretation (propositions, truth)
 Prior Analytics (syllogistic logic)
 Posterior Analytics (scientific method)
 Topics (rules for argument and debate)
 On Sophistical Refutations (fallacies)
 Science and nature
 Physics (change, motion, void, time)
 On the Heavens (not the religious concept: refers to astronomy)
 On Generation and Corruption (on the process of life)
 Meteorology (origin of comets, weather, disasters)
 The Parva Naturalia (psychological works)
 Sense and sensibilia (faculties, senses, mind, imagination)
 On Memory,
 Sleep, Dreams, and Prophesy
 Length of life
 Works on natural history
 History of Animals
 On the parts of Animals
 On the Movement of Animals
 On the Progression of Animals
 On the Generation of Animals
 Problems
 Philosophical works
 Metaphysics (substance, cause, form, potentiality)
 Nicomachean Ethics (soul, happiness, virtue, friendship)
 Eudemian Ethics, virtues & vices
 Politics (best states, utopias)
 Rhetoric (debate)
 Poetics (tragedy, epic poetry)
 The Constitution of the Athenians
 Fragments

Influence of Aristotle's work 
Aristotle is still one of the most influential people who ever lived. He contributed to almost every kind of knowledge in his day, and he started many new fields. 
"It is doubtful whether any human being has ever known as much as he did".

Aristotle was the founder of formal logic, pioneered the study of zoology, and helped to develop scientific method.

Despite these achievements, Aristotle's errors are thought by some, such as Peter Medawar, to have held back science considerably. Bertrand Russell notes that "almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine". Russell also refers to Aristotle's Ethics as "repulsive", and calls his logic "as definitely antiquated as Ptolemaic astronomy". Russell says these errors make it difficult to do historical justice to Aristotle, until one remembers what an advance he made on his predecessors.

The immediate influence of Aristotle's work was felt as the Lyceum grew into the Peripatetic school of philosophers. Aristotle's influence over Alexander the Great is seen in the latter's bringing with him, on his expedition,  biologists and researchers.

Related pages
List of biologists

References

Other websites 

 Works by Aristotle

384 BC births
322 BC deaths
Ancient Greek philosophers
Ancient Greek writers
Polymaths