The Milesians and the origin of philosophy


In the standard account of the history of Western philosophy, philosophy begins in 624 BCE in ancient Greece with the birth of Thales (THAY-lees). Thales and his two successors, Anaximander (an-AX-ih-man-der) and Anaximenes (an-ax-IH-men-ees), were based out of the city of Miletus (my-LEE-tus), and hence are known collectively as the Milesian (my-LEE-zhin) philosophers. They were among the first of the so-called Presocratic philosophers (mostly philosophers born before Socrates1).

The geography of Miletus is notable, because when we say that philosophy began in ancient Greece, it is not Athens or even the Greek mainland of which we speak. Back in the time of the Milesians, if you sailed east from the Greek mainland, crossing the Aegean Sea until you hit the coast of what is now called Anatolia, you would have landed in a region then known as Ionia, which consisted of a league of Greek colonies. Miletus, situated a little bit south of Ephesus, was one of these colonies. To the east of Ionia was the kingdom of Lydia, which actually ended up conquering Ionia; even further to the east was the Persian Empire, which in turn ended up conquering both Lydia and Ionia around 545 BCE.2

Let’s take a quick look at what the Milesians are purported to have said.


Thales (ca. 624-546 BCE) is most noted for three claims:

  1. Everything is made of water.
  2. Everything is full of gods.
  3. Magnets have souls.

What does all of this mean?

The most popular interpretation of the first claim is that Thales literally believed that everything is made of water. Why would he say this? Aristotle speculates that Thales observed that living things like plants grow when you give them water, as though the water is transformed into the solid structure of the plant. Thales may also have noticed that water has three phases; water is the only substance an average person in a climate like Ionia’s would experience variously as a liquid, a solid, and a gas. Perhaps Thales extrapolated from this that water could become so dense that it would manifest as earth or so vaporous that it would manifest as air or fire. Since we no longer have anything Thales wrote, it is difficult to know for sure what motivated him, but the standard story presumes that he arrived at his conclusion by reasoning carefully about possible explanations for what he observed; as we will see, this is why Thales is considered a philosopher at all.

How about the claim that everything is full of gods? That claim is even more obscure, and few commentators seem to know what to do with it. Let’s talk about the third claim, and return to the second claim afterward.

Thales’s third claim is that magnets have souls. What could possibly lead him to say this? Magnets behave very strangely when compared to other metal things.3 They seem almost alive, as though there are things they are seeking out or objectives they are trying to accomplish. Thales took this as evidence that magnets have souls, because the ancient Greeks thought that possession of a soul is what makes something alive and active rather nonliving and inert. Note that on this view, a soul is not necessarily an extra thing added to the matter that makes up an object, as though destroying a magnet would release a ghost; rather, a soul is inseparable from the object itself. Aristotle runs with this kind of idea more than two hundred years later when he argues that a soul of an object is the organization of the object’s matter in a way that enables it to seek fulfillment of some goal.

Now that we have talked about magnets and souls we may have a clue as to what Thales means by his second claim, when he says that everything is full of gods. If we understand gods to be appropriately similar to souls, then Thales may just be saying that everything behaves purposefully, though perhaps not always as obviously, as animals or magnets. Why, on this account, would he use the word gods instead of souls? Perhaps to express a degree of reverence toward the cosmos: if one thinks that all of nature, down to rocks and pebbles, is animate, it is for some a very short step to thinking of it as divine. Is this interpretation of Thales speculative? Assuredly: speculation is inevitable when was has so little source material.


Anaximander (ca. 610-546 BCE) apparently agreed with Thales that there must be one fundamental thing underlying everything else, but he disagreed with the idea that it must be something familiar, like earth, water, air, or fire. Instead, Anaximander held that the fundamental thing was something entirely other—something he called the apeiron, which translates into the “boundless” or the “infinite.” Anaximander actually proposed a cosmological model in which there initially is nothing but the apeiron, but the innate rotating motion of the apeiron eventually causes all of the familiar elements to separate out of it (making the heavens and the earth in the process). Whether Anaximander meant that everything continues to this day fundamentally to be composed of apeiron, or just that everything started out from apeiron, is not entirely clear.

Notably, Anaximander also thought that life came into being by spontaneous generation from moisture, and that humans originally were born to fish-like ancestors in the distant past. Presumably he came to the latter conclusion by observing that human infants cannot nourish themselves, and deducing from this that the very first humans would have died unless they had gestated as fish do, wihout needing to nurse.


Anaximenes (ca. 570-525 BCE) agreed with Thales that everything is in fact made of a traditional element, but he argued that the element in question is air, not water. Many people think Anaximenes is a step backward from Anaximander—a naive retreat from the sophisticated and ineffable back to the crude and familiar. Others think this is unfair; Anaximenes, they contend, thought that the concept of apeiron was too obscure to be helpful, and realized that the hypothesis that everything is made of air could account better for everything he could observe. Anaximenes also gave an account of how air can transform into other substances: it is all a matter of density, with sufficiently compressed air turning into water and earth, and sufficiently rarified air turning into fire. He came to this not by a pure flight of fancy, but by extrapolating from what he could observe; he noticed, for instance, that one can make one’s own breath either hot or cold by varying how much one compresses the stream of air through one’s lips.

The Importance of the Milesians

At this point, you may be on the verge of making a solemn vow never to bother with philosophy again. If the Milesians made such outlandish claims, why do we think they were important? Why, in particular, would we consider them founders of an entirely new discipline? To understand the answer, we have to compare what the Milesians thought, and the methods by which they came to their conclusions, with what came before. The account I will give of this is the standard account one finds in most of the literature; I have some reservations about it, but it is the standard account, so I’ll put my reservations aside for now.

First, before the Milesians came on the scene (and, for most people, also while the Milesians were on the scene, and even after they had left the scene) the received view was that nature behaves as it does because of the activity of gods whose personalities were very much like the personalities of humans. It followed, therefore, that to understand the behavior of nature one could go no deeper than to understand the moods and motives of the gods. The Milesians bucked this trend by developing a naturalistic view of the world in which they analyzed the world into fundamental constituents (water, or apeiron, or air) whose behavior was not capricious at all; by understanding the behavior of these fundamental constituents, one could in principle understand everything in the world. It is much less important that Thales thought the world was made of water, or that Anaximenes thought it was made of air, than that they believed it could be understood by appealing to the ordered behavior of a kind of substance with no fundamental caprice. Anaximander, though dispensing with familiar elements, produces a full cosmological model in which the world as we know it is formed through purely mechanical action. This kind of metaphysics is one of the things that signals the beginning of philosophy, because it introduces the idea that nature is amenable to investigation by observation and rational thought.

For the average ancient Greek, to understand nature meant understanding the gods; but to understand the gods, one had to appeal to privileged sources of knowledge—to the authority of poets like Homer and Hesiod, who had been inspired by the Muses, or to oracles who received messages directly from the other gods. Thales and his successors would have none of this when it came to understanding the natural world; instead, they appealed to that which everyone could perceive with their own senses, and to that which everyone could (at least in principle) figure out through the power of their own reason. Thales, we recall, supposedly concluded that magnets have souls not because he thought Zeus was whispering secret knowledge into his ear, but because he thought it was the best explanation for the observable behavior of magnets. Anaximenes concluded that air can transform into other elements by extrapolating from an observed correlation between air pressure and temperature. It is this reliance upon reason and empirical evidence that defines philosophy, and the Milesian reliance upon these methods that truly entitles them to be called the first philosophers.


1 For some reason, Democritus is considered a Presocratic philosopher, despite both having been born after Socrates and having outlived him.

2 The King of Lydia at the time was none other than King Croesus, who, according to legend, attacked the Persian Empire after consulting the Oracle at Delphi. When Croesus had asked what would happen if he attacked, the oracle supposedly said, “a great empire will fall.” The great empire that fell, of course, was Lydia, and the Ionian colonies fell with it. The moral of the story is, don’t listen to oracles.

3 This was at one time an obvious NSFW pop-culture reference. Now it may just be proof that I am aging.