Natural Philosophy

 

The first philosopher we know of is Thales. He thought that the source of all things was water. We do not exactly know what he meant by that. Perhaps he observed that all life originated from water and returns to water again when it dissolves. It is likely that Thales thought about the way water turns into ice and turns into water again. Thales is also said to have said that all things are full of “gods.” We do not exactly know what he meant by that. Perhaps, seeing how the earth is the source of crops, he believed that the earth was filled with life-giving forces. But it is fairly certain that he was not talking about Homer’s gods.

Anaximenes is also from Miletus. He thought that the source of all things must be air or vapor. He was familiar with Thales’ theory of water. He thought that water was condensed air. When it rains air is pressed to form water, when it is pressed even more it becomes earth. He thought that fire was the absence of air. Hence, he thought that the source of all things was air.

Anaximander also lived in Miletus. He thought that our world was only one of a myriad of worlds that evolve and dissolve in something called the “boundless.” It is clear that the boundless would be unlimited and uncreated because everything created is limited. Unlike Thales and Anaximenes, he did not reduce everything to a single known element, but instead to an indefinite origin that cannot be directly observed.

Empedocles believed that there were four roots of everything: Earth, Fire, Air and Water. All natural processes are coming together and separation of these four elements. Nothing is created or destroyed, only mixed and separated. He also believed there were two forces at work, “Love” and “Strife.” Love binds things together while strife separates them. He distinguishes between substance and force.

Parmenides thought that everything that exists had always existed. Nothing can come from nothing. He observed that the world around him is constantly changing, but he thought that change is an illusion. He believed that his senses provide incomplete information and cannot be trusted. He was one of the most important philosophers from Elea, and the Eleatic philosophers mostly dealt with the problem of change.

Heraclitus is the opposite of Parmenides. He believed that senses can be trusted and that everything is in constant flux. “You cannot step into the same river twice.” He pointed out that the world is characterized by opposites like day and night, war and peace, hunger and satiety. He believed there must be a universal order behind this constant change, which he called Logos. For him this unity was the underlying structure of everything.

Democritus believed that nature was made up of tiny indivisible particles called atoms. Change, according to him, is just atoms arranging and rearranging themselves. Atom means “uncuttable.” He believed atoms cannot be divided further, unlike Anaxagoras. If they could be divided forever, nature would dissolve into an infinite and unusable mixture. He also believed that nothing comes from nothing, so atoms must be eternal and solid. He thought there were infinite types of atoms, combining through hooks and barbs.

Democritus did not believe in any force or soul. He believed only in atoms and the void, and was therefore a materialist. He also had a theory of perception, where we see things because tiny atomic images are emitted from objects and enter the senses.