Why Anaximenes thought that the source of everything was air
Anaximenes (586 - 526 BC) was an early Greek philosopher from Miletus, a Greek city on the coast of what is today Turkey. He believed that, in some way, the source or principle of everything was air. Let’s talk about why and what this means.
Lots of translators tend to say that Anaximenes believed that the principle of everything was air. That’s a translation of the Greek word ‘arkhē’, which literally means ‘source’, and although ‘principle’ tends to be the most common translation, ‘source’ is probably the best because it captures Anaximenes’ idea pretty intuitively.
He thinks that air is what everything comes to be from.
Here’s one report of what he thought, for instance:
“Anaximenes, son of Eurystratus, a Milesian, asserted that air is the first principle [or, source] of the things that exist; for everything comes into being from air and is resolved again into it. For example, our souls, he says, being air, hold us together, and breath and air contain the whole world ('air' and 'breath' are used synonymously).”
We don’t have any books from Anaximenes, so we have to piece together his views and reasoning from such reports. Sadly, we have only five reports about Anaximenes’ views in total. But this report, and some others, do give us some idea about his views.
When Anaximenes says that air is the principle or source of everything, what he seems to have meant is that everything is made of air, was originally air, and will eventually be transformed into air again. This is a paraphrase of the report I just quoted, but another report lets us unpack the ideas even further.
Here is a bit of another report: “as it [that is, air] is condensed and rarefied it appears different: when it dissolves into a more rarefied condition it becomes fire; and winds, again, are condensed air, and cloud is produced from air by compression. Again, when it is more condensed it is water, when still further condensed it is earth, and when it is as dense as possible it is stones. Thus the most important factors in coming into being are opposites — hot and cold.”
This is a complicated passage, and it is packed with a lot of information. It reveals the basic thought here: when Anaximenes says that everything was originally air, he means that the things that we know in this world — mountains, trees, etc. — really are air.
Why don’t they look like air? That’s because air appears different when it is rarefied (i.e., made less dense) and when it is condensed/compressed.
When air is made less dense, or rarefied, it becomes fire.
Condensed air becomes wind, and even more condensed air becomes water, and the more dense it becomes, it can even become earth and, ultimately, stones.
The last sentence of the report is interesting: hot and cold are the most important factors. It’s hard to know what exactly this means because the report doesn’t clarify, but it seems that he thinks that you rarefy, or make less dense, air by adding heat to it; you make it more dense by adding cold to it. Cold and hot produce the relevant transformation.
This seems to be confirmed by a brief report that says the following: “he [that is, Anaximenes] says that matter which is concentrated and condensed is cold, while that which is rare and slack (that is the word he uses) is hot.”
Anaximenes seems to have thought that since fire is hot and is rarefied air, heat must be what turned air into fire, and since dense air, such as earth and water, is cold, cold must be what made air dense.
With this theory, Anaximenes has reduced the apparent plurality of the world into just one element: air. If Anaximenes could change today’s periodic table of elements, he’d transform it into having just one element: air. Earth, water, air, and fire are the classic list of elements, but Anaximenes thinks that the world is actually just made of air.
For this reason, historians of philosophy think of Anaximenes as a monist: someone who believes that everything is actually just made of one underlying substance.
In the report I quoted above, attributed to Anaximenes is the belief that our souls are made of air and that air contains the whole cosmos: “our souls, he says, being air, hold us together, and breath and air contain the whole world.”
Once we understand Anaximenes’ views, this isn’t really surprising. Our souls are made of air; everything is! Air contains the whole cosmos; of course, it does; what else would? Everything all around us is air. Even our bodies are just air in a certain state of density.
It is hard for us to say why any of these ideas occurred to Anaximenes in the first place. It is true and no doubt important that many thinkers in Miletus at the time were beginning to think this way: what is everything made of? People tried different answers, such as water and fire, but Anaximenes gravitated towards air.
Clearly, one reason why he thought this was that air struck him as something that could undergo what he saw as the relevant transformations: rarefaction and compression. He seemed to find it implausible that the water we’re drinking could actually be earth, but he seems to have had no problem thinking that what we drink is actually dense air.
Perhaps he was also struck by the way that air is such a vital part of the world. He thought it was a crucial part of us: respiration is a hugely important part of being alive as humans.
That being said, it is tremendously not obvious why Anaximenes held his views. What makes him stand out to us is that he was the first early Greek philosopher to specify a mechanism by which the one thing (in virtue of which he was a monist) gets transformed. His predecessors thought that, say, water was the source or principle of everything, but it isn’t clear how you get from water to mountains and suns.
However, Anaximenes’s focus on air is paired with the mechanisms of compression and rarefaction. For that reason, he is an integral part of the history of philosophy.