(625?-546? BC).  

Home: Miletus, Asia Minor.  

School: Great Ionian

First Proposed Physis: As a "cosmologist", he was the first to speak about the idea of a "physis" or a fundamental reality common to the whole universe. He proposed water as this substance. (Considering that water contains hydrogen, the basic component to the universe, this was not a bad idea). Since he was the first to begin the search, he is known as the First "Physicist" 

Rational or Empirical Viewpoint? Edit

Empiricist. He felt knowledge of nature important. He tried to avoid mythological answers.


The founder of Greek philosophy. One of the Seven Wise Men of Greece.  

Greatest achievementEdit

Founder of the critical tradition. Also, denying superstition, Thales assumed that there was an orderly universe or a Kosmos that could be understood by the human mind. Both of these concepts are at the epistemological foundation of science. 

Surviving worksEdit

None. Known only through Aristotle's Metaphysics and other fragments/quotations of his works.


Thales was famed for his knowledge of astronomy after predicting the eclipse of the sun May 28, 585 BC. The practical outcomes of his meteorological predictions, (which enabled him to corner the olive oil market), probably did more to impress Greeks on the value of empiricism than all of his philosophical works. He is also said to have introduced geometry in Greece, which he found in Egypt. (The Egyptians used it to plan farm plots... and did not otherwise consider of any great importance.)

Thales was among the first scientists (not experimental, however) in the world. He was primarily an astronomer, and he astonished the people of Miletus by telling them that from his observations, the sun and the stars must be nothing more than balls of fire. With these words, Thales introduced the concept of using mundane explanations for "god-like" phenomena.

Before Thales, explanations of the universe were mythological. His empiricism and concentration on the basic physical substance of the world - what he called the "physis" marks the birth of scientific thought - and marks him as the first physicist. His most significant advancement to general scientific thought was his acceptance and promulgation of criticism - fostering analysis of his works rather than demanding dogmatic acceptance. Once criticism was seen as a benefit, science would flourish. "Science" without criticism is religion or mythology. It could very well be that the entire world owes its present state of scientific thought to Thales.

When Thales said that water was the physis, this made him the first to propose a purely material universe, based on a universal substratum that itself was unchanging, and, underlaying all change. This would mean that Thales was the first metaphysician in that he believed he had found the "essence" of existence - the "thing" remains unchanged even as all else changes. This line of thought is of the greatest significance possible. To understand why, we must consider what problem Thales was struggling to solve.

The Problem - as stated by Charles Van Doren in "A History of Knowledge"

"As we look around us, we percieve a vast assortment of different things, all of which , as far as we can tell, are in a state of constant change. Living things are born, grow and die. The sea is in constant motion, the air, even the mountains whither away. Even the universe changes. Does everything change then, or is there something that does not?"
And, if there is not some "thing in itself" that remains unchanged, that endures, no matter how much we tear apart, alter, boil, bake, cook, or otherwise change a given material, then how can we even conceive of such a things as being constant? How can we even perceive a knowable universe? All would be meaningless and chaos. If there is not primordial substance, then the universe must be an illusion.
Thales considered this problem and came to the conclusion that the universe was no illusion, much like Descartes 2000 years later. So he tried to find some primordial substance to the cosmos, some enduring principle, to all of the universe. This cosmological thinking made him a cosmologist - and the primordial substance he came up with was water.
Now, let me tell you that it is not clear that Thales meant to say that "water" literally was the physis. In fact, he probably didn't. After all, he could see that water itself seemed to change - i.e. water becomes steam or ice with a simple change in temperature. Thales probably more likely meant that the "physis" was something more like "wetness" or "mallebility" - i.e. the very thing that underlied water's own ability to change so much.

Whatever the validity of his work, in doing this, Thales gave birth to two paradigms that have universal historical significance.

1   He rejected the religious propensity to appeal to wonder or ignorance, i.e. "I do not know why this is happening, therefore the gods made it happen." - which is the heart of anti-intellectualism. Saying "god did it" is not an answer - it's the admission that you have no answer.

2   He made the extraodinary assumption that the entire cosmos could be understood by the human mind.

Thales believed that the totality of things in the cosmos could be understsood. It was orderly and intelligible. It is not a mystery, nor the play things of the gods. Science starts when supernatural explanations are rejected in favor of seeking naturalistic answers.

However, it is vital to appreciate that Thales did not include the mind among material objects. While he did say that the world is intelligible and that there is a deep commensurability between the external world and the human mind, he did not include the mind with the external world. So it can be said then that Thales was a dualist and not a strict materialist - so he laid down the groundwork the later works of Socrates and Plato, as well as for Descartes.

I wish I could point you to more information on Thales, but what I have presented here represents a near totality of what I have seen in other works. But take a look around the internet, more information is constantly popping up.