Thales, Anaximander, and Anaximenes were from Miletus, which is on the Ionian coast of Asia Minor. Their great successor Heraclitus was from Ephesus, which is on the same coast. Together these Ionian thinkers of the sixth and late fifth centuries brought about one of the most significant revolutions we know of, one that set the civilized world on a path it has followed, with minor and not so minor deviations, ever since. What they did, to put it boldly and rather simply, was to invent critical rationality. For the theories they advanced, whether on the nature and origins of the cosmos or on ethics and politics, were not offered as gospels to be accepted on divine or human authority or, like Hesiod’s cosmology, on the authority of the Muses, but as rational constructions to be accepted or rejected on the basis of evidence and argument. Every university and college, every intellectual discipline and scientific advance, every step towards freedom and away from ignorance, superstition, and enslavement to repressive dogma is eloquent testimony to the power of their invention. If they had not existed, our world would not exist.
Of these thinkers, Thales was the first. His reputation in antiquity was immense. He was one of the fabled Seven Sages (Solon was another). He is credited with being able to predict solar eclipses and with determining the height of the pyramids by measuring the length of their shadows. Whether he wrote anything is unknown. If he did, no genuine fragment of it has survived. But despite the fact that we possess none of Thales’ original words, we do know that he held that everything is water, or something to that effect.
The first thing to notice about this claim is that it says that there is really only one thing—water—and that everything else is in some way made up of or built out of it. We don’t know just why Thales assigned such a fundamental role to water. Perhaps, as Aristotle claims, he noticed that water is essential in various ways to the existence of living things (Metaphysics, 983b22–27), or that water alone exists naturally as a solid, liquid, and gas, and so might be the fundamental stuff from which all things were made. If Thales did think in either of these ways, his doctrine is a prototype of many fundamental scientific doctrines. It is based (no doubt somewhat loosely) on evidence and argument, and it suggests that a single thing underlies and explains the apparent diversity of phenomena. Modern scientists who claim that everything is mass-energy or that the four-dimensional space-time continuum is the only real thing are heirs to Thales.
Two ancient stories about Thales are worth repeating, because of the somewhat different light they cast on early philosophy. The first is recounted in Plato’s Theaetetus:
Once while Thales was gazing upwards while doing astronomy, he fell into a well. A clever and delightful Thracian serving girl is said to have made fun of him, since he was eager to know the things in the heavens but failed to notice what was in front of him and right next to his feet (174a4–8).
The second story might be thought of as Thales’ slightly revengeful response to the servant-girl. It is found in Aristotle’s Politics:
The story goes that when they found fault with him [Thales] for his poverty, supposing that philosophy is useless, he learned from his astronomy that there would be a large crop of olives. Then, while it was still winter, he obtained a little money and made deposits on all the olive presses both in Miletus and in Chios. Since no one bid against him, he rented them cheaply. When the right time came, suddenly many tried to get the presses all at once, and he rented them out on whatever terms he wished, and so made a great deal of money. In this way he proved that philosophers can easily be wealthy if they desire, but this is not what they are interested in (I 11 1259a9–18).
The moral of the story is that apparently arcane knowledge can have important practical uses, so that philosophy can help us to live well, and that we neglect it at our peril (see Plato, Republic 487d ff.).
Anaximander was a younger contemporary of Thales. Only a few words of his writings have survived, but ancient sources give us a vivid idea of their astonishing scope. They contained a cosmogony, or account of the origins of the cosmos; an account of the origins of life; astronomical, meteorological, and biological speculations; and a map of the known world. Our primary interest is in Anaximander’s most general explanatory doctrine, but a brief glimpse at two of his other views shows what a daring thinker he was.
The first of these concerns the origin of human beings:
[Anaximander] also declares that in the beginning humans were born from other kinds of animals, since other animals quickly manage on their own, and humans alone require lengthy nursing. For this reason, in the beginning, they would not have been preserved if they had been like this.
Here an observation coupled with an insightful piece of argument leads to a daring hypothesis: Human beings were not made by gods. They came from other animals.
The second piece of Anaximandrian speculation concerns the ancient question of what holds up the earth. Thales seems to have held that the earth is floating on water, “as if,” Aristotle witheringly comments, “the same question did not arise . . . for the water supporting the earth” (De Caelo 294a32–23). Aware, perhaps, of this defect in Thales’ answer and in other similar ones, Anaximander proposed a different kind of answer altogether. He declared that
the earth is at rest on account of its similarity. For it is no more fitting for what is established at the center and equally related to the extremes to move up rather than down or sideways. And it is impossible for it to make a move simultaneously in opposite directions. Therefore, it is at rest of necessity.
In other words, the earth doesn’t move, not because it’s held up by something else, but because there’s nothing to cause it to move in one way rather than another. The cleverness of this answer is obvious, since it gets around the kind of criticism that Aristotle uses against Thales.
I turn now to Anaximander’s fundamental doctrine:
Of those who declare that the first principle is one, moving, and indefinite, Anaximander . . . said that the indefinite was the first principle and element of things that are . . . He says that the first principle is neither water nor any other of the things called elements, but some other nature which is indefinite, out of which come to be all the heavens and the worlds in them.