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The Pre-Socratics - From Natural to Ethical Philosophy

Pre-Socratic and Early Greek Philosophy


The Pre-Socratics - From Natural to Ethical Philosophy

Sum of Squares - Pythagorean Theorem


Greek Philosophy to Natural Philosophy > From Natural to Ethical Philosophy

In the Beginning Was the ...

The early Greek philosophers, from Ionia, (Asia Minor) and Magna Graecia in southern Italy, saw the world around them and asked questions about it. Instead of attributing its creation to anthropomorphic gods, they sought rational explanations. This was the beginning of natural philosophy.

These philosophers were developing a brand new field. They came up with creative ideas, quickly focusing on things like the cause of change and what might be the principle, the archê (ἀρχή), underlying everything else. Logos (λόγος) was another term used for a guiding principle. Written centuries later, the Logos principle of the Greek New Testament is connected with the same word archê: Ἐν ἀρχῇ ἦν ὁ Λόγος....

The Pre-Socratics also argued, discredited, borrowed freely from, and adapted the advances of each another.

Pre-Socratic Explanations of the Universe

One Underlying Substance

One idea the Pre-Socratic philosophers had was that there was a single underlying substance. This substance had to account for everything in the world. Since not everything looks alike or remains in the same state, there had to be a principles of change, and if there were only one substance, this principle must be contained within the underlying substance.

Aristotle (384-322 B.C.) is not one of the Pre-Socratics. By definition, the Pre-Socratics should come before Socrates, but the end date isn't as firm as the idea that with Socrates came the new philosophical schools of his student Plato and then Aristotle. Although these are not Pre-Socratic schools, their founders did discuss the Pre-Socratics. In his Metaphysics Aristotle reviews them. He writes:

Thus it is clear that Wisdom is knowledge of certain principles and causes.
[982a] [1]

The first philosopher to write in prose and the man credited with creating the gnomon, Anaximander of Miletus (c. 611-547), equated the arche principle with apeiron (ἄπειρον), the boundless, without origin, immortal, and impersonal phusis = nature and the source of our word physics, according to IEP. In effect, he said that nature -- lower case, and not a god -- is the source of everything. Others posited something only a tad less abstract. (There ideas are complex. I am vastly over-simplifying here. You'll get a taste for what I'm talking about when you read the fragments from Kirk, Raven and Schofield.)



One candidate for the substance was water. The important Pre-Socratic philosopher Thales of Miletus (fl. 1st quarter of the 6th century) is credited with coming up with this one. Within water there might be such principles as evaporation and condensation, so it could become gaseous or solid. The earth floated in water. There were problems with considering water the underlying principle -- for instance, it defies our experience to think fire is composed of water, As with all the single element theories, there was a difficult to surmount obstacle: the issue of accounting for changed states.

Thales, the founder of this school of philosophy, says the permanent entity is water (which is why he also propounded that the earth floats on water). Presumably he derived this assumption from seeing that the nutriment of everything is moist, and that heat itself is generated from moisture and depends upon it for its existence (and that from which a thing is generated is always its first principle). He derived his assumption, then, from this; and also from the fact that the seeds of everything have a moist nature, whereas water is the first principle of the nature of moist things.
Metaphysics 983.b


Air was another contender.

Anaximenes and Diogenes held that air is prior to water, and is of all corporeal elements most truly the first principle.
Metaphysics 984a
Fr. 141 Anaximenes...said the inifinite air was the principle, from which the things that are becoming, and that are, and that shall be, and gods and things divine, all come into being, and the rest from its products....
The Presocratic Philosophers: A Critical History With a Selection of Texts, by Geoffrey Stephen Kirk, John Earle Raven, Malcolm Schofield.


Heraclitus (fl. 500 B.C.) thought it was fire.

Fr. 219 All things are an equal exchange for fire and fire for all things, as goods for gold and gold for goods.
The Presocratic Philosophers: A Critical History With a Selection of Texts, by Geoffrey Stephen Kirk, John Earle Raven, Malcolm Schofield.

Kirk, Raven and Schofield explain:

"The world is an ever-living fire, parts of which are always extinguished to form the other two main world-masses, sea and earth. Changes between fire, sea, and earth balance each other; pure, or aitherial, fire has a directive capacity... The pure cosmic fire was probably identified by Heraclitus with aither... the brilliant fiery stuf which fills the shining sky...."

Not One Element but a Particle or Many

Atomist School and Pluralist Philosophies

  • From such revolutionary, if problematic ideas, they came up with the idea that the underlying substance must be very small, like an atom. Did I mention (some) Greek Pre-Socratic philosophers were brilliant?

  • Another idea was that there wasn't a single underlying substance, but several elements, specifically, earth, air, fire, and water, which were associated by the medical followers of Hippocrates with the four humors of the body. In varying proportions, these four elements were thought to have created everything in the world.

While those of us not totally in awe of these thinkers may laugh at their ideas, they are not really that different from modern science, which posits elements, too, in the form of the periodic table of the elements, and Higgs Boson, atoms, and quarks, etc. as the underlying building principles and blocks of matter.

Expanding Focus of Philosophy

In addition to looking at the building blocks of matter, some early philosophers were actually poets forcing their observations into the strict dictates of poetic meter. Just try explaining the world around you in Haiku. They looked all around them -- at the stars, music, and number systems.


Early scientists used numbers to count and measure such things as distances on earth, around the earth, or to heavenly bodies.

The study of the measure of earth is geo- (earth) + metry (measure).


Thales is credited with bringing geometry to Greece from Egypt where it was implicit in the construction of the pyramids. He is also credited with work in engineering.


A third century B.C. Greek mathematician, Eratosthenes, living in Alexandria, Egypt (the site of the famous library) used geometry to estimate (reasonably well) the circumference of the earth. His measurement presumes a spherical globe, contrary to any medieval idea of a flat world.

The Pythagorean School

Probably the most famous of the early Greek philosophers that are known collectively as the Pre-Socratics is the 6th century B.C. philosopher Pythagoras, who may have actually lived and may have invented the theorem named for him -- or not.

The Pythagorean Theorem says that the square of/on the hypotenuse equals the sum of the squares of/on the two sides, but what Pythagoras would have demonstrated is not something complicated involving a square roots table. Instead, he would have shown that if you position 3 squares of specific dimensions so that they form a right triangle in their center, there is a sum of squares relationship between the hypotenuse and the other two sides, as shown in the illustration.

Not all squares put together will produce this remarkable arrangement. It depends on the relationship between the length of a side of each of the three squares.

There are other numbers that behave oddly, and the Pythagoreans deduced that certain numbers have special properties.

Interests Beyond Natural Philosophy

The school of Pythagoras concerned itself with other aspects of the world besides natural philosophy.


The Pythagoreans developed rules for behavior. For instance, since they believed in transmigration of the soul or progressive reincarnations, they thought it was wrong (a sort of cannibalism) to eat meat, echoed later by Empedocles.

Later philosophers focused entirely on conduct or ethics. Instead of asking what made the world, they asked what was the best way to live.

  • Should people be involved in public life or not?
  • Should they attempt to experience the greatest pleasure or should they seek to avoid all highs and lows?
  • Is wealth good?
  • Should someone seeking to be good (i.e., philosopher) give up all the material trappings of life and get all he needs to survive by begging?
Such a lifestyle was later adopted by Christians, especially mendicant monks. Philosophy was capable of being used as a tool by the dominant powers or it could be private, a source of consolation. A good emperor of Rome, Marcus Aurelius, is known as a Stoic philosopher and for writing his philosophical meditations.

Philosophers as Sages and Sagacious Women

Philosophers were thought of as sages. Thales was considered one of the 7 greatest sages. Philosophers wore beards. Well after the Pre-Socratic period, Emperor Julian the Apostate was more an erudite philosopher (and bearded) than simply a pagan believer in the old stories, which made his religious preferences no more desirable than Christianity. There were also (beardless) women philosophers, although not many are known. The Pythagoreans had accepted women into their school. Hypatia of Alexandria taught neo-Platonist philosophy and Aspasia of Miletus (yes, she is another Ionian) taught male philosophers.


Our knowledge of the Pre-Socratic philosophers comes from fragments of their works included in the writing of others. The Presocratic Philosophers: A Critical History with a Selection of Texts, by G.S. Kirk and J.E. Raven provides these fragments in English.
Diogenes Laertius provides biographies of the Pre-Socratic philosophers: Lives of Eminent Philosophers, Loeb Classical Library.

Next: Are you ready for the Quiz? Otherwise, perhaps you would like to review the article on the emergence of philosophical thinking in the world of Greek mythology: Greek Philosophy to Natural Philosophy.

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