# Galileo's Science/Natural Philosophy

Aristotle

Aristotle and Natural Philosophy

Aristotle(384 BC – 322 BC) was the greatest philosopher of ancient Greece.He had discussed almost all the branches of knowledge.Studying Nature was essentially one of his principal interest.Knowledge of nature or natural philosophy is physis in Greek from which the word Physics derived.Aristotle covered this in his several works such as Physics, On The Heavens, Meteorology etc.He set the principles of natural philosophy in Metaphysics.

Aristotle proposed four elements of which all natural objects on earth consist of.They are Air, Water, Earth and Fire.He also proposed that the heavenly bodies or objects in the sky(stars, planets, moon etc.) are completely independent of earth and they are made of another completely different thing called quintessence.Quintessence itself and objects made of it do not change with time or any other cause.

Aristotle assumed earth as the center of the universe, according to him all objects in the universe rotates around earth.

According to Aristotle every event is lead by a cause and principal objective of natural philosophy is to find causes behind events.

According to Aristotle's dynamics the natural state of all body is static, everything tends to be static.Some force applied on an object makes it moving or an object gains velocity if force is applied.When the force is withdrawn objects eventually return to their natural state or become static.Mathematically Aristotle says force(F) is proportional to velocity(v) or ${\displaystyle F\propto v}$ which is completely contradictory to the modern view that force(F) is proportional to acceleration(a) or ${\displaystyle F\propto a}$

But Natural Philosophy was gradually proving unable to describe nature. Some doctrines (like Copernicus` Heliocentric Model of the solar system) against it was growing outside universities.