 Hi, I'm Peter Adamson and you're listening to the History of Philosophy podcast, brought to you with the support of King's College London and the Leverhulme Trust. Today's episode, Mind Over Mixture, Anaxagoras. In a dialogue called The Phaedo, Plato shows us the last conversation of Socrates. It will end when Socrates drinks the hemlock and bravely prepares to meet whatever the afterlife may hold for him. But first, he indulges in a bit of autobiography, telling his friends, soon to be his mourners, about his early philosophical explorations. In this story he gives a central role to Anaxagoras. Socrates says he came across Anaxagoras' book, which could apparently be picked up cheap in Athens toward the end of the 5th century BC. At first, he found the book promising. Anaxagoras offered an account of how the cosmos is produced and ordered by mind, which, Socrates assumed, meant that Anaxagoras would go on to explain why everything in the world is for the best. Instead, the book turned out to consist largely of crude physical explanations, invoking things like the hot and the cold, the rarified and the dense. Disappointed, Socrates went off on his own way and, at least according to Plato, invented the theory of forms. In a later episode, we'll look at this dialogue in its own right. But I wanted to start with it today, because I think the passage captures so well a kind of duality in Anaxagoras' philosophy. On the one hand, there is his exalted mind, the purest and most subtle of things, which plays a central role in forming the cosmos. On the other hand, there is his fascination with physical processes, and, above all, his startling theory of universal mixture. Everything is in everything, according to Anaxagoras, except for mind. Anyone trying to come to grips with Anaxagoras should try to do what Socrates wasn't able to, that is, they should try to understand not only how the theory of mind and the theory of mixed physical substances, but also how mind and the physical substances themselves interact. It's not surprising that Anaxagoras' book could be found in Athens in Socrates' day, because Anaxagoras' philosophical activity was spent in Athens. In fact, he was the most notable philosopher of Athens until Socrates came along. We always think of Athens as the capital city of Greek philosophy, but as you may have noticed, so far none of the philosophers we've looked at came from Athens or spent a significant part of their lives there. Anaxagoras was the first to do so, and he is thus something of a one-man symbol for the transfer of philosophy from Ionia to Athens. He was from Klasomenai on the Ionian coast, and he continued some of the traditions of Ionian philosophy going back to the Milesians in the 6th century BC. Despite this, it was in Athens that he seems to have done his philosophy, and it was in Athens that he became associated with the great statesman Pericles. As the leading politician of the democracy of Athens in the middle of the 5th century, Pericles helped to build the empire that would face off against Sparta in the Peloponnesian War starting in 431 BC. But Pericles' career mostly coincided with the more peaceful period of increasing Athenian strength after the wars with Persia but before the disastrous conflict with the Spartans. It's appropriate that Pericles should have consorted with a philosopher of Anaxagoras' stature, given that it was under his leadership that Athens developed into a preeminent power and thus a center for philosophical speculation and other cultural activities. This was the environment in which Socrates was formed. Anaxagoras has something else in common with Socrates apart from his association with Athens. Like Socrates, he was put on trial for being insufficiently reverential towards the gods. He didn't wind up drinking hemlock, but instead just left town, which is safer. Unfortunately, we don't know much about the trial, but it may have resulted from his political connections. Then again, his theory of the cosmic mind is not much like traditional Greek religion, so it may have been, as they say, a fair cop when he was accused of impiety. That's not to say that Anaxagoras' mind is anything less than divine. At least, it sure sounds like he is talking about God or a God when he describes mind. He says that it is infinite and controls everything that lives. This may put us in mind of Sinophanes' version of God, or even Heraclitus' version of fire. It seems to me that when Socrates started to read Anaxagoras' book, this was probably also the impression that he formed. Mind was going to be a powerful, perhaps even all-powerful, god who planned and designed everything so that it would be as good as it can possibly be. He then became disappointed when Anaxagoras didn't invoke mind constantly, but appealed to various material processes instead. But I think this was a bit unfair on Socrates' part. There's a grand tradition in both philosophy and religion of invoking God or the gods to explain the fact that the world looks so well-designed. Think about how the sun moves in just the right way to give us the seasons, so that we can plant and harvest food to keep ourselves alive. Think of the giraffe with its long neck, just the thing for reaching those tasty leaves in the trees. Think even of how much it hurts when you step on something sharp. Sure, you don't feel grateful when it happens, but if not for the pain, you'd be a lot less careful in the future, and you'd probably wind up with cuts all over your feet, and then where would you be? So even the bad things in life seemed designed to make life better. Socrates assumed that this is roughly where Anaxagoras was heading when he put mind in charge of the cosmos. There may have been something like this thought in Anaxagoras' mind, but the evidence we have suggests that he actually had other fish to fry. For one thing, the fragment that tells us about mind controlling things says that it controls living things, so maybe giraffes and people who can step on rocks, but not the rocks that the people are stepping on. His idea seems to be not that mind is responsible for how well-designed things are, but for the special abilities of things like people, animals, and maybe plants. He says that of the things that have mind, some have a greater share, and some a lesser share. Presumably humans have more than dogs, and dogs have more than insects. Perhaps some humans have more than others. Now, none of this sounds anything like the Creator God we know from religions like Christianity, Judaism, and Islam. Anaxagoras' mind is not there to explain why everything is designed as well as possible, but to explain why some things can think, see, and so on, whereas others can't. We humans get a healthy portion of mind, rocks don't get any. In short, it sounds more like Anaxagoras' mind is an ingredient, or a power, which is distributed unequally throughout the universe. But if mind is an ingredient, then it is a very special ingredient. Anaxagoras reserves a unique place for it when he explains how the world is put together. And this takes us to his other most famous idea, universal mixture. Before the cosmos was formed, Anaxagoras says, there was nothing but mind and another infinite substance, in which all other things were mixed together. However, there were, in amongst this mixture, what he calls seeds. These seeds were the beginnings of later distinctive substances like, for example, air or water. Only mind stands outside this mixture. It must be over and above the things it is going to control, so it alone is, as he says, unmixed. Furthermore, mind has the important job of kicking off the formation of the cosmos. It somehow initiates a cosmic rotation, in which the infinite mixture of stuff starts to spin around. As the rotation goes on, the seeds of lighter things are sifted out towards the edges and become air and the fiery stuff of the heavens, while the seeds of moist and dense things stay towards the middle. At some point, some large stones go spinning out of the central portion and become the visible heavenly bodies like the sun and moon, burning white with heat. So far this sounds a lot like what we've found in the earlier Ionian philosophers. In particular, we already saw in Anaximenes the idea that the bodies in the middle of the cosmos where we are collect there because they are dense, whereas air and fire are rarefied and light. It's almost as if Anaxagoras has put this together with Xenophanes's God, who just by thinking shakes all things. But Anaxagoras is adding something of his own as well. Even though the seeds are separated out by the rotation that mind sets in motion, nothing apart from mind is ever completely separated. Instead, as he puts it in his most famous slogan, everything is in everything. The oceans may look to us like they are made only of water, but actually they also contain things other than water, for instance air and fire. In fact, all things contain all other kinds of thing. So, when soul singers from the 1970s to the present have informed us that everything is everything, they were broadly speaking in agreement with Anaxagoras. As far as I'm concerned, that alone makes it worth trying to understand what he was up to with this theory. As usual, Aristotle has an explanation of what Anaxagoras was up to, and as occasionally happens, Aristotle's explanation may actually be right this time. He puts Anaxagoras's theory squarely in the context of the Parmenidean denial of change. You might remember that for Parmenides and his followers, motion and change were impossible, because for anything to come into being, it would have to come from non-being, but there is no non-being. Aristotle suggests that Anaxagoras accepted part of this reasoning. He agreed that nothing could come from absolute non-being, and yet, like the atomists, he refused to accept that nothing ever really changes or moves. The atomists go one direction here, and Anaxagoras goes the other. For the atomists, in one sense there is no change, because all the atoms are eternal, they never come to be and are never destroyed. So nothing comes to be from non-being, but the atoms can come together in different configurations which underlie the world we see around us. Anaxagoras rather ingeniously suggests instead that absolute change is not required because everything is already everything else. He gave the example of food. You eat a loaf of bread with a hunk of cheese on it, and this manages to restore the flesh, bone, and blood in your body. Clearly there must be flesh, bone, and blood in the bread and cheese. After all, there's nowhere else for it to come from. And there's another contrast between Anaxagoras and the atomists. He's happy to accept, in the face of Zeno's paradoxes, that you can take any material body and divide it, divide it again, and so on and so on, infinitely. But every portion of that body, no matter how small, will still contain all things. Even the tiniest particle of cheese has some bone in it. Anaxagoras then would have us believe that every single material object, or part of an object, no matter how small or large, contains all the ingredients that make up the universe. You cannot separate out any one ingredient to get, say, pure and unmixed bone or flesh. As we saw, only mind is ever unmixed. Rather, what you get if you start cutting up cheese is smaller and smaller bits of cheese, which still contain all the other ingredients. It's not mind you that the cheese can be turned into bone. The idea is that there is already bone in the cheese, and in everything else. Now, this raises a couple of obvious questions. First of all, will any of us ever want to eat cheese again? Second, if all the ingredients are in every portion of everything, why doesn't everything look the same? It should all be one homogeneous mass with no differentiation between cheese and bone or anything else. The answer to this is fairly easy. Even if all ingredients are present in a given chunk of the world, they might be present in different proportions. A chunk of earth, for instance, has all the ingredients in it, but the earth in the chunk predominates all the other ingredients. We might say that there are trace elements of other things like water and fire in the earth. Similarly, there are trace elements of flesh, blood, and bone in the cheese. The process of digestion pulls these trace elements together to build up our body, which is made of portions, which likewise have all ingredients, but are predominantly flesh or predominantly bone. Apparently, this sort of predominance has always been present because there were seeds of things already in the infinite mass that mind began to rotate. These seeds were portions which were already predominantly cold or hot or whatever. Of course, it had to be like this if the rotation begun by mind was going to achieve anything. After all, the hot bits can hardly get spun out towards the edges if no one bit is hotter than any other bit. Another thing we might wonder is what exactly is the list of the ingredients? Is it really the case that everything is in everything? Do we really want to say that inside every particle of a giraffe there is just a hint of Eiffel Tower, and vice versa? Here we've reached a somewhat controversial area of Anaxagoras' philosophy. Some have thought that he was working with a fairly short list of ingredients, which in fact don't look much like ingredients at all. These would be things like hot, cold, rare, and dense. If this is his theory, it isn't quite as surprising as it first seemed. His point would only be that nothing is so hot that it has no admixture of cold or vice versa. Rather, there would be a kind of continuum between hot and cold, and similarly for other basic oppositions, like perhaps moist and dry. We might envision this by imagining a measurement scale with no top or bottom, no absolute zero in the case of temperature. He instead explains it in the more concrete terms of a physical mixture. This would be in keeping with other prezocratic philosophers, and even some later thinkers like Aristotle, who speak of things like the hot and the cold as kinds of stuff rather than measurable properties. But others find this version of Anaxagoras harder to swallow than bony cheese. Some ancient authors, including Aristotle and others who could probably have read Anaxagoras' own writings, seem happy to speak of things like bone and flesh among the ingredients that are always present. On the other hand, there's no reason to think that the ingredients included more complicated things like plants, animals, and humans, to say nothing of man-made things like tables and the Eiffel Tower. Rather, he seems to have had in mind the simplest materials out of which such things are made. In the case of the Eiffel Tower, this would be metal. In the case of a giraffe, it would be good old bone, flesh, and blood. I might add that Anaxagoras could afford to be relaxed about the list of ingredients if he wanted to. He could say to us, I've given you the theory of universal mixture, which is my breakthrough insight. We'd need a detailed investigation to find out what the basic constituents of the universe are, but my theory could turn out to be true, whatever those exact ingredients turn out to be. In this spirit, we might note that, even though there is no bone in cheese, there is calcium in cheese, and bone is partly made of calcium. See, not so crazy after all. With this theory, Anaxagoras put on the table a philosophical problem which was going to worry philosophers for many generations to come. This is the problem of mixture. It's not something that leaps to mind nowadays when we think about pressing philosophical difficulties. Does God exist? What is the nature of consciousness? Sure. But what is it for one thing to be mixed with another? Not so much. Yet, this problem was at the heart of ancient attempts to understand the nature of material objects. If we don't worry about the problem anymore, it's because one answer to the question eventually carried the day. We now think that when two things like water and wine get mixed together, what is actually happening is not so much mixture, as a very complicated jumbling together. There are wine particles and water particles, and these particles don't literally fuse, they just get juxtaposed. This is, of course, precisely the answer that the ancient atomists would have given, and at least to this extent, they were right. Anaxagoras was proposing a different sort of answer which would turn out to be more popular among ancient philosophers like Aristotle and the Stoics. According to this second answer, it is indeed possible for one body to be completely mixed with another. In fact, the Stoics said it was possible for a single drop of wine to mix with the entire ocean, so that every portion of the ocean no matter how small would have some of the wine in it. No one apart from Anaxagoras went so far as to say that absolutely every type of body can be found absolutely everywhere, but his fundamental intuition about mixture is perfectly reasonable. After all, we see wine mixed with water, and the two seem to suffuse one another completely. Why not think this is happening, as it were, all the way down, including in portions of the mixture too small to see? Once you've gotten to that point, you need to accept Anaxagoras's idea that one ingredient can predominate over another, even if the two ingredients are mixed with one another through and through. Obviously, in the ocean mixed with a wine drop, water is predominant, even though wine is present absolutely everywhere in the water. Anaxagoras then brings together many of the themes we have seen in other pre-Socratic philosophers, and he is a kind of bridge to Socrates and post-Socratic philosophy as well. With Anaxagoras, we have brought philosophy to Athens, seen another response to Parmenides, and also been reminded of the grand cosmic theories of the Milesians. Along with the Eliatics and the Atomists, Anaxagoras exemplifies the ambitious system building that we find in 5th century BC philosophy up until Socrates, and even during Socrates's own lifetime, for instance with the development of Leucippus's atomism at the hands of Democritus. But there's one major pre-Socratic from the 5th century who we haven't examined yet, Empedocles. There are some signs that Anaxagoras was responding to Empedocles rather than the other way around, even though Anaxagoras seems to have been born slightly earlier. Aristotle is constantly presenting the two of them together, comparing their two cosmic schemes in various ways. Like Anaxagoras, Empedocles was very influential, responsible for systematizing the four elements of earth, air, fire, and water. He was also a wonderfully over-the-top wise man in the style of Pythagoras. He claimed to be an incarnate god, capable of working miraculous healing, and he supposedly died by hurling himself into a volcano. That's Empedocles, a philosopher who knew how to make an exit, next week on The History of Philosophy Without Any Gaps.