Plato – born 428 BC
Plato was – unfortunately – probably the most influential philosopher of all time. Most of early Christianity was derived from his philosophy.
His main ideas were:
Utopia
Theory of universals
Immortality
Cosmogony
Knowledge as reminiscence rather than perception
He was a well to do aristocrat born in 428 BC. When Athens was defeated in 400 BC
he blamed democracy and embraced totalitarianism. He was a pupil of Socrates and became a prolific master of propaganda. He believed that leisure was essential to wisdom and ideally wise men should be chosen to govern – but how? Government should be by aristocrats or state supported individuals, and not workers. The best state involved a minimum of change. Rulers needed intellectual and moral discipline, or will become corrupt. Solution – teach them geometry!
He was influenced by:
Pythagoras – Orphic elements – mysticism, intellect and immortality
Parmenides – reality is eternal and timeless, change is illusory
Heraclitus – nothing is permanent. Knowledge is achieved by intellect ( ie not by scientific research)
Socrates – ideology, and teleological causation. Eternal good
Sparta – the myth
Aristotle – born 384 BC in Thrace
Aristotle was undoubtedly one of the most influential philosophers. Whereas Plato influenced the early Christian church, Aristotle became supreme in the middle ages (C13) and all his teachings were regarded as gospel. He took the first steps in creating a systematic and professional methodology based on sound principles of logic, but his enormous influence fossilised any further advances for 2,000 years. That was not his fault.
He was not revolutionary. He accepted most of the conventions and beliefs of his time, but wove them into his own framework. He could not help being influenced by Plato’s writings, but he tried to minimise the mystical and Orphic influences and to combine Plato’s ideas with a degree of common sense – not easily done as they do not mix readily and the results are often confusing.
He did not understand the mechanistic notion of motion ( Only Democritus and Archimedes truly understood this) but believed in “physics” as the nature that gave movement to animals and the heavenly bodies.
He believed that the Earth was at the centre of the universe. Everything from the Moon outwards was ungenerated and indestructible. Everything below the Moon (sublunary) was subject to generation and decay.
He believed that everything sublunary was made of the 4 elements – earth, water, air and fire. Everything outside the Moon was made of the fifth element, and was naturally in circular motion. His teachings in this area were a major obstacle to astronomy for 2,000 years.
He taught the young Alexander as a boy in Athens around 330 BC, but is unlikely to have influenced the headstrong teenager.