The common thread connecting these three philosophers from Miletus is a project now called ‘reductionism.’
Looking at the variety in the world around them, these men asked whether there was some unifying reality which produced all of it, constituted all of it, and made it all intelligible. For these three thinkers, this was primarily on the level of physical objects.
What do a flower, a rock, a cloud, and the planet Jupiter all have in common? They are all composed of matter. But matter manifests itself in these divergent — very divergent — ways. What makes all these different things fall into the same category?
Phrasing the questions in a twenty-first century way, one might ask, what properties does all matter share? Certainly, a flower growing in a garden and the planet Jupiter seem to have very little in common. If they are both made of matter, then it is necessary to more closely understand what matter is.
The three Milesian philosophers were looking for a universal and ubiquitous principle — the basis of all matter — which would be the source and substance for everything. In this way, they are not so different from modern physicists.
The modern answer to the Milesian question might be: “Everything is made of protons, electrons, and neutrons.”
Seen in this way, the suggestion that everything is foundationally composed of water, or air, or some indeterminate stuff which has the capability of becoming water or air or fire or dirt, is not so odd. Interpreted with charity, these suggestions make sense, even if they’re not quite correct.
Water is composed of hydrogen and oxygen. Oxygen is the most common element in the earth’s crust, and hydrogen is the most common element in the universe. These two substances are everywhere in the environments which human beings inhabit. The rocks, plants, animals, and other objects encountered in daily life on earth are full of these two substances.
The choice of air as a potential primordial source for everything likewise has some reasonable aspects. The air on Earth is approximately 21% oxygen, and as noted above, oxygen is ubiquitous. Earth’s air is often laden with water, whether as clouds or as invisible vapor, which therefore includes hydrogen. Additionally, air is often filled with dust, which could be fine particulates of silicon, iron, or anything else.
The hypothesis of some primary substance called the ‘indeterminate’ — the ‘boundless’ or the ‘unlimited’ in various attempts to translate Anaximander’s Greek into English — resembles the concept of an undifferentiated stem cell, which can become any of many different types of cell, and resembles the concept of basic particles in physics, which can form atoms of any type.
The reductionist project of Thales, Anaximander, and Anaximenes is, then, not as odd as it seems, and has a significant similarity to aspects of modern physics.
