The fundamental stuff out of which everything else is made or comes to be isn’t any of the four recognized elements—earth, water, fire, and air (or dry, wet, hot, and cold)—but a fifth thing, the unlimited. Why? According to Aristotle (Physics III 5 204b22–29), Anaximander argued, “If everything is water, then everything must have the properties of water. But not only do some things lack these properties, some even have properties that are the opposites of those possessed by water: Earth isn’t wet, it’s dry. Since nothing can be both wet and dry, how can dry earth just be some form of wet water? How can what just is wet water become dry?” This is a powerful argument for thinking that if there is a single stuff of which all things (including the elements) are made, it cannot have any definite characteristics of its own. It must be indeterminate in quality.
More significantly, this Anaximandrian argument is a telling criticism of his predecessor, Thales. Consequently, it’s a good example of the critical rationality I praise the Greek philosophers for inventing. Anaximander didn’t accept Thales’ doctrines on his authority or, as we are asked to accept Hesiod’s cosmogony, on the authority of the Muses; rather, he submitted them to rational scrutiny, modifying those that failed to pass muster and accepting only those that did. In the Nicomachean Ethics, just as he is about to criticize the doctrines of his own teacher, Plato, Aristotle recommends this as the appropriate attitude for a philosopher to take to his forebears:
It presumably seems better, indeed only right, to destroy even what is close to us if that is the way to preserve the truth. And we must especially do this when we are philosophers, [lovers of wisdom]; for though we love both the truth and our friends, piety requires us to honour the truth first (I 6 1096a).
Paradoxically, then, it is by destroying Thales’ doctrines, rather than by accepting them unquestioningly, that Anaximander reveals himself as Thales’ true heir.
In addition to criticizing Thales’ doctrines, Anaximander also made an important suggestion about what causes the elements to interact and give rise to the things we see around us:
The things that are perish into the things out of which they come to be, according to necessity, for they pay penalty and retribution to each other for their injustice in accordance with the ordering of time.
His idea seems to be that elements, conceived of as opposite powers (dry/wet, hot/cold), struggle with one another, with sometimes one gaining the upper hand, sometimes another. When this happens the balance or equilibrium of the cosmos is disturbed: one opposite has gained “unjustly” at the expense of another, and must of necessity—or because of the laws governing the cosmos—pay reparation to it in due course, so that equilibrium is restored once more. No doubt this is, indeed, “rather poetical,” as Simplicius puts it, but it certainly shouldn’t be dismissed on that account. For it contains the fundamentally important notion that the natural world is governed by necessity (by law) not by the arbitrary whim of the gods. Many good and fruitful theories start their lives as metaphors.
Anaximander’s follower, Anaximenes, developed Anaximander’s account of the elements and introduced significant economies into it. In Anaximander’s cosmology, there are four elements (earth, water, fire, and air) as well as the somewhat mysterious indeterminate stuff, whose relation to them is not fully explained. Thus Anaximander has five fundamental things in his ontology. Anaximenes seems to have realized that the unlimited was unnecessary baggage, that one of the elements could play its role. He claimed that air is the fundamental principle of everything, and that earth, water, and fire are simply air which is to different degrees either rarefied or condensed. Earth is very dense air; fire is very rarefied air:
The form of air is the following: when it is most even, it is invisible, but it is revealed by the cold and the hot and the wet, and movement. ... For when it is dissolved into what is finer, it comes to be fire, and on the other hand air comes to be winds when it becomes condensed. Cloud results from air through felting, and water when this happens to a greater degree. When condensed still more it becomes earth, and when it reaches the absolutely densest stage it becomes stones.
Thus Anaximenes’ theory is at once simpler and more complete than Anaximander’s. It needs only one thing—air—where Anaximander’s needs five. Moreover, it explains in a straightforward way what Anaximander leaves mysterious: how the one fundamental stuff can give rise to the other elements that appear in the world. This makes it a better theory and another good example of critical rationality—or a critically rational tradition—in operation.
The next step in this line of argument was taken by Heraclitus of Ephesus, a consummate thinker and writer, if a rather difficult one. In the following fragments, he speaks of the birth of one element as the death of another.
It is death to souls to become water, death to water to become earth, but from earth comes water and from water soul.
Fire lives the death of earth and air lives the death of fire, water lives the death of air, earth that of water.
If we set out the claims they make in a table, we can see that they describe the series of transformations already familiar to us from Anaximenes: