DeDanaan

This is an excerpt originally from: Galileo and Einstein: Early Greek Science: Thales to Plato
A lecture by Michael Fowler, UVa Physics Department
[Additional links and annotations by Áine MacDermot]

The Milesians

The first recorded important contributions to Greek science are from the city of Miletus, near the coast of what is now Turkey, beginning with Thales in about 585 B.C., followed by Anaximander about 555 B.C., then Anaximenes in 535 B.C. We shall argue below that these Milesians were the first to do real science, immediately recognizable as such to a modern scientist, as opposed to developing new technologies.

To see where Miletus is, click here.

The crucial contribution of Thales to scientific thought was the discovery of nature. By this, we mean the idea that the natural phenomena we see around us are explicable in terms of matter interacting by natural laws, and are not the results of arbitrary acts by gods. An example is Thales’ theory of earthquakes, which was that the (presumed flat) earth is actually floating on a vast ocean, and disturbances in that ocean occasionally cause the earth to shake or even crack, just as they would a large boat. (Recall the Greeks were a seafaring nation.) The common Greek belief at the time was that the earthquakes were caused by the anger of Poseidon, god of the sea. Lightning was similarly the anger of Zeus. Later, Anaximander suggested lightning was caused by clouds being split up by the wind, which in fact is not far from the truth.

[Note : Modern commentators assume that Thales regarded the earth as flat, thin, and circular, but there is no ancient testimony to support that opinion. On the contrary, Aristotle may have attributed knowledge of the sphericity of the earth to Thales, an opinion which was later reported by Aëtius (Aët. III. 9-10) and followed by Ps.-Plutarch (Epit. III.10).]

The main point here is that the gods are just not mentioned in analyzing these phenomena. The Milesians’ view is that nature is a dynamic entity evolving in accordance with some admittedly not fully understood laws, but not being micromanaged by a bunch of gods using it to vent their anger or whatever on hapless humanity.

An essential part of the Milesians’ success in developing a picture of nature was that they engaged in open, rational, critical debate about each others ideas. It was tacitly assumed that all the theories and explanations were directly competitive with one another, and all should be open to public scrutiny, so that they could be debated and judged. This is still the way scientists work. Each contribution, even that of an Einstein, depends heavily on what has gone before.

The theories of the Milesians fall into two groups:

(1) theories regarding particular phenomena or problems, of the type discussed above,

(2) doctrines of general cosmological import.

A spectacular example of the second type of theory was Anaximander’s suggestion that the earth was actually a cylinder, and the sun, moon and stars were located on concentric rotating cylinders. This is the first recorded attempt at a mechanical model of the universe. He postulated that the stars themselves were rings of fire. Again, this was a revolutionary suggestion, as all heavenly bodies had previously been regarded as living gods.

He also considered the problem of the origin of life, which becomes more difficult to explain if you don’t believe in gods. He suggested that the lower forms of life might be generated by the action of sunlight on moist earth. He also realized that a human baby is not self-sufficient for quite a long time, so postulated that the first humans were born from a certain type of fish known at that time.

All three of these Milesians struggled with the puzzle of the origin of the universe, what was here at the beginning, and what things are made of. Thales suggested that in the beginning there was only water, so somehow everything was made of it. Anaximander supposed that initially there was a boundless chaos, and the universe grew from this as from a seed. Anaximenes had a more sophisticated approach, to modern eyes. His suggestion was that originally there was only air (really meaning a gas) and the liquids and solids we see around us were formed by condensation. Notice that this means a simple initial state develops into our world using physical processes which were already familiar. Of course this leaves a lot to explain, but it’s on the right track.