 Sociologically, it was a philosophical school that arose in the Hellenistic period. It had recruits, it tried to steal away members from other schools to join Epicureanism. In fact, there's kind of a humorous anecdote. Epicureanism grew and grew in popularity and was getting more and more converts. And somebody asked a Stoic philosopher, why is it that people always convert to Epicureanism, but it doesn't seem to go the other way, like Epicureans converting to Stoicism. And the Stoic responded, because eunuchs are made from men, not vice versa. And that's just one example of the kind of high grade attack rhetoric that was deployed against Epicureanism. And eventually in late antiquity, Epicureanism became characterized as this atheistic, hedonistic, amoral system of philosophy that the church fathers waged war on and essentially destroyed. And almost all of the texts were therefore lost. And so for Epicureanism itself, we're dependent once again on the biography of Diogenes Laertius, who we've been using, we read several of his biographical points last week. And also a poem that happens to survive in Latin by Lucretius called De Rere Natura or On the Nature of Things, which is a gigantic hexameter, didactic home about Epicureanism. And we can look at some excerpts of that that are contained in this translation of the fragments, but it's a work well worth accessing and studying itself. In fact, there's recently been a lot of enthusiasm for that work, as you can tell from various anthologies and support that have been written on it included on the bibliography. A book by Stephen Greenblatt, a Renaissance scholar last year called The Swerve, which was about the recovery of Lucretius's De Rere Natura in the Renaissance, won the National Book Award and so forth. Now Epicurean, but that's about all I'm going to say about the sociology and the development of the schools and so forth. People certainly could research that for a project, but I'm going to focus on the ideas in the school. And so we begin by talking about the traditional division of philosophy. They basically accept the division into logic, physics, and ethics, except that they have a very nuanced view of what logic is, and in fact they refuse to use the term logic and they use the term canonic. Instead, a canon is something like a standard or a criterion for knowledge, and they think that the only purpose in doing logic is to come up with what the standard or criterion for knowledge is. And they discard a lot of the traditional aspects of logic, including rhetoric, dialectic, and so forth as being worthless, they're completely focused on standards for knowledge. But they of course have physics, that is they have a theory of nature and ethics, and here they use the traditional terminology. I can give a bare summary of their views with respect to these three different schools. So with respect to logic or canonic, they are empiricists. Empiricism is the doctrine that all knowledge originates in sensation or perception. And they are certainly some of the most extreme empiricists because they accept this doctrine that all knowledge originates in sensation or perception. In physics, they're what we call materialists. And materialism is the thesis that everything that exists is made out of matter and is a material object, and there aren't really supernatural entities that aren't constructed out of matter. Specifically, they're atomists, so they have a discrete or discontinuous theory of matter. More on that in a moment. In ethics, we can just summarize their view as hedonism. Hedonism is the doctrine that the end of life is pleasure. That is the goal or aim of life is pleasure. So empiricism, materialism, and hedonism to put it in a nutshell. And I think this is a philosophy that we can really relate to because I think that most of us essentially believe this. We believe in empiricism, we believe in materialism, we believe in hedonism, or at least that's how we act. So usually we act as if they're objects that are real must be material objects and that if somebody says they know something, that must relate somehow to their perception. And that ethics has something to do with pleasure. If it has anything more than that, then it would need to be established. Question already? Well, you said that most of us seem to believe in these things. Yeah. If you ask me, I would say... No, I didn't ask you. I said most of us believe in them. No, I was just... It seems like most people, though, would not be materialists because most people seem to believe in supernatural entities, at least. Yeah, I disagree. I don't think they really do. But I mean, people say they do, but people that end up believing in ghosts and things like that think that they're actually material objects. But anyway, it has no relevance for my explanation of Epicureanism. The point is that it's easy for us to accept. It's easy to convince people that they ought to believe that those things are real. And it's very difficult to convince people of ethical views like, nothing matters except virtue, or the end of life is some kind of intellectual activity and everything else should be in the service of that. It's not very smart to convince people that the point of life is really to enjoy it and to get some kind of pleasure out of it. And it's very difficult to convince people that you can have all-priori knowledge that has no connection whatsoever to sensation or perception. But it's pretty easy to get people to believe that we can know things if we can verify them with our senses and that sort of thing. Now, all of those views might be wrong, might be mutually incoherent, meaning it's difficult to hold them all together, or individually they might be problematic, or people might have a tendency to reject one or more of them. Like they think that we can come to knowledge by some other means than perception or they think that ethics probably does have something to do with more than pleasure. The only point I'm making is that this is essentially the closest philosophy as a package to what most people believe and what we're teaching in most other parts of the university. So when we're teaching physics, we're teaching about material reality. When we're teaching theory of knowledge and how to learn, we're talking about how to do experiments and how to use what we can sense and what we can perceive to build theories about what actually exists. And when we're doing ethics, we're doing something like utilitarianism where we're assuming that maximizing pleasure and minimizing pain is an overall goal even of our politics and social policy and that sort of thing. So I guess I can refine my view. Maybe if we went and pulled each individual person, they would disagree with some part of that. But when we compare it to the views that we were looking at last week, Peronian skepticism, you shouldn't have any beliefs or a sense to anything. Sinicism, you should throw all your money into the ocean and live on the streets. Aristopian hedonism, nothing matters except a constant succession of pleasures. I mean, these are somewhat alien views that we think these are crazy Greek people that believe this, but could anyone actually live this way? This is not a very challenging philosophy to see how you could live this way. In fact, probably if you started examining your beliefs, you will find a lot of agreement with them. Now, logic and physics are taken by them merely to be the starting point of the philosophy while ethics is the end. So essentially the only reason they care about logic or physics is for an ethical purpose. So this is a quotation from a text on page 97 of the textbook, but it's very short and you should probably just memorize it and it goes like this. Empty are the words of a philosopher that relieve no suffering. So if your words are not ultimately conducive to relieving suffering of some kind, they're empty and worthless. Or a quote, principle doctrine number 11 on page 33, if our suspicions about meteorology or heavenly phenomenon and moreover, if not knowing the limits of pains and desires didn't trouble us, then we have no need of natural philosophy or natural science at all. We wouldn't need to do it. It might be interesting to do, but we wouldn't really need to do it unless it was somehow conducive to relieving our fears and anxieties about what reality is like. So in a way, logic and physics are completely in the service of this ethical end. Now again, by logic, they call logic canonic and that means basically three things. One, an analysis of words that we use in order to determine what, if anything, in reality they actually refer to the use of sensations and feelings as a basis for distinguishing what is evident from what is non-evident. And three, a method of inference from what is evident to what is non-evident. And I think the first two of these are fairly clear. We have to take our concepts, we have to analyze them, we have to define them in order to figure out what we're talking about. And sometimes our concepts don't make any sense in that case we need to eliminate them. In other cases, a concept is missing by something that's revealed to us in experience and we need to invent some new terminology for that. And we also look at our sensations and that's considered taken very generally. Our sensations, our perceptions, the outcomes of our experiments and so forth in order to determine what is evident and what is non-evident, the difficult thing is how we infer what is evident from what is non-evident. And to give one of their leading examples, suppose you're sitting in a darkened room in which there's light streaming through a window, then you may have observed that there's dust particles that sort of float and dance around in this sunbeam. And they don't just move straight downwards, they move side to side and somewhat sometimes they seem to move upwards and then generally their trajectory is downwards but they don't have a straight downwards movement, instead they sort of move side to side. Well, one can infer from this that there must be smaller particles, smaller than the visible pieces of dust with which the pieces of dust are colliding that make them move side to side instead of straight downwards since the natural motion of dust particles due to gravity or whatever would be to move in a straight line downwards but in fact they don't move that way and we don't have an evident cause so we have to infer that there must be some other particles that they're colliding with that we can't see. So they're saying if you're not sensing something, they're not existing? That's exactly the opposite of what they're saying. Exactly. So we're talking about a method, so I should slow down here. We're talking about a method of how one infers from something that is not evident, something that is evident. So when I'm watching dust move side to side instead of straight downwards in a sunbeam in the room, I don't see that it's colliding with other pieces of dust. I don't see that there are actually other particles that are making it move that way. I have to infer that there must be particles that I can't see that's making them move side to side. Therefore I can infer that invisible particles must exist. There must actually be material particles there that are causing that motion that are too small for me to see. So you see why I say somewhat obnoxiously it's exactly the opposite of what you said. It's not that only what we can see is true. It's that either we have a sense perception of it and so we infer that it's true or we infer that something else must be the case on the basis of what we can see. But those inferences can be about things that we can't actually see. So it was a lot of it based off of the concept that something cannot come from nothing. So you kind of have to make that inference? Well that is one of the first principles. In fact that is the first principle of their physics. Nothing is ever generated from nothing. The second principle of their physics is nothing is ever destroyed into nothing. Because when he was talking about sound he kind of said the same thing you said before that something can't come from nothing. So when you're saying something and somebody else hears it you have to infer that there are particles moving from the speaker to the listener. Yes exactly. There must be a medium here and there must be waves or something that are going through it. Otherwise I wouldn't be able to hear it. And we can't see any of that. I can't see any of these waves or these particles that are going between your mouth and my ears. But we can infer that they must exist because we can perceive that we hear things. I can perceive that you're speaking. You can see your lips moving and I can see that I hear something. I don't see musical notes or something going in between them but I can infer that there must be some physical bodies that are mediating between that. I'm not sure exactly how that is tied to the idea that nothing is generated from nothing or nothing is destroyed from nothing. But those are certainly basic principles that they hold. And by the way those are very ancient principles. Much more ancient than Epicureanism. So pre-Socratic philosophers had already figured that point out which we now have fancy names for like principle of conservation of matter, principle of conservation of energy is just that exact principle. Nothing pops into existence out of nothing and nothing can be completely obliterated or destroyed into nothing. There's always what you can do is break matter up into smaller pieces and put it together into bigger ones but you can't bring things totally new into existence or completely obliterate things. Further, they hold the totality of the universe. And when I use the word universe I'm really serious about that. There's exactly one of them. There's this loose talk going around recently about universes and it's total nonsense because if you've got several universes in mind they're all part of my one universe. And they talk about multiple worlds. We can have as many worlds as we want. We can have an infinite number in fact of Cosmoid or worlds, planetary systems, galaxies or whatever. But all of those constitute one universe and if we're talking about the universe as a whole nothing in it according to them has changed. So this view is totally opposed to the more recent views developed since the mid 20th century according to which the universe did come into existence at a certain point of time from nothing and 15 billion years ago and that it's fundamentally changed. That it's expanding and so it's much larger than it ever was and so forth. They claim that if we're talking about the level of the whole universe nothing changes and we essentially have a steady state. And again our views about the Big Bang give rise to a lot of paradoxes like if we strictly speaking take it as generation from nothing then the Big Bang conflicts with our principles of conservation of matter and so forth. Every Koreans don't have any of those problems. So do they have an explanation of how it started them? Well it didn't start according to them. It's always existed infinitely backwards in time and so they ridicule those views according to which it did start at a given time and they say things like well what was happening right before it started. They also hold that it's infinite in all directions so they run the same kind of argument about space. It can't end at some point because what happens if you go up to that edge and you try to go a little bit further. So it's infinite spatially and temporally. I think the Big Bang theory is that the whole universe was the size of like a dime and so in terms of this the space like the void between each of the particles which is actually small. Yeah it's actually they talk about infinitely dense you know a singularity and that sort of thing. And if we think of the Big Bang as being bringing into existence just one world as multi so-called multiverse theory holds that there's like an infinite number of worlds and what's come into existence in the Big Bang is just one world among many. Again this is where the confusion of people talking about universes coming into being. Universes don't come into being, worlds come into being. Then it could be consistent with their view. So in their view a world is just a temporary a world or a cosmos. The Greek word's cosmos that's where we get the terms like cosmology. A world is just a temporary envelopment of some matter. They worlds come into existence and go out of existence. So that part of the Big Bang story is totally consistent with their cosmology. Yeah. So worlds come into existence and they disappear. Isn't the universe of all kind of changing? As a whole no because that's always been happening and what's happening is just rearrangement of matter. The fundamental composition of the universe is the infinity of the universe in time and all of that is exactly the same. But it's changed in the sense that in one region there might be a lot more dense matter that happens to be collected there temporarily than in another region. So it changes in that sense and you could have a sort of history of the universe in that sense. But what's the fundamental aspects that haven't changed like we now talk about with the Big Bang how microseconds after the Big Bang there were different values for certain physical constants and things like that. And that's what they hold as an implication. Gravity always works the same wherever you are in the universe and so on. So let me come back to that point by giving, I mean all we've done is give some basic heuristic principles of their physics. The substance of their physics is that the totality or the universe consists of basically two things. Bodies in motion. Well, it consists of bodies in motion through void or empty space. Now the existence of bodies is evident to sense perception. So I'm looking out here at a bunch of bodies. Even if there weren't any people in this room I'd be looking at a bunch of bodies because our bodies, furniture's bodies, animals, plants, buildings and everything are made out of bodies. And if you're wondering whether bodies exist you can do things like touch this and easily get a confirmation of yes that Epicureans seem to be right about that. There really are bodies out there. Now what we don't however see that there is void or empty space. We don't see here or feel the existence of void but we infer its existence from the fact that we notice that bodies are in motion. Again, I can see here and feel that bodies are moving. I see, you know, pens moving across the page and people getting up and down and doors opening and closing and that sort of thing. And I infer that there must therefore be void but if there wasn't void or empty space none of that motion could seem to be happening because there wouldn't be any room for you to move your pen or for the door to be open. You have to assume there is some empty space there that the door opens into. So again, it's another case of inference from what is evident to what is non-evident. It's evident that there is void but we can infer that there is void from the phenomena of bodies in motion. One concept that I didn't completely or fully understand was the idea of the images. Well, in order to understand that we have to do a lot more basic stuff of their physics first. And by the way, it's a very... their doctrine of images and how perception works is extremely difficult. Both the topic in general of how perception works is difficult for everyone. It seems to imply action to a distance and a bunch of other things. But the Epicurean doctrine specifically is hard. So I'm not... I'm glad it was difficult for you because that means you actually read it and tried to make sense of these... these crazy claims that they're making. I'll try to say a bit more about it as we get further. Although we will have more to say about that also in the context of their ethics. Because one... because we have to talk about their theory of perception and sensation in connection with the phenomena of pleasure and pain which relates to their ethics. Now, so, but all I've shown... all I've argued so far is that there are bodies moving through void or empty spaces. Now I'll point out that among bodies some are compounds and some are simple. So compounds just means they're collected out of other smaller bodies like this podium is made out of four or five different pieces of wood so it's a compound thing. It's not a simple object. And human bodies are made out of flesh and bones and limbs and eyes and brains and so forth so they're obviously composite bodies because they have many parts. According to the Epicureans however we can take these compounds apart eventually we must arrive at an entity that is indivisible. And we call this entity an atom. And the word atom the Greek word atom literally means indivisible entity. A thing that is not cuttable is what atom means. Now, only compounds are visible because atoms by themselves are too small to see compounds include everything that we see including all the artifacts that I just mentioned plants, animals but also the heavenly bodies the stars, the planets the sun, the moon even whole worlds like solar systems, galaxies clusters, super clusters all of those are just greater and greater combinations, compounds compounded entities. And all compounds are destructible and not just destructible but eventually will be destroyed just as they all come into existence at a certain point in time so they are all destroyed in time and what happens, their destruction is just dissolution into their constituent parts or atoms but atoms themselves can't be resolved into anything else because they're atoms that is they're indivisible so they cannot be divided and cannot be destroyed otherwise we would run afoul of the principle that nothing can be destroyed absolutely nothing the maximum you can do in terms of destruction is to take a compound and resolve it into atomic bodies you cannot get any further from that but in the infinite expanse of time if it were possible to divide and destroy everything then everything they say would have been destroyed but it is evident that not everything has been destroyed because there are compound bodies in motion as is evident to my senses therefore there must be there must be indestructible entities and those are the atoms now just a brief aside about the terminology of atoms we still use this Greek term but now we have this theory that the atom can be divided by splitting the atom but more seriously we talk about parts of the atom so we talk about subatomic particles like electrons, protons, neutrons and so forth okay well fine then perhaps those are the indivisible entities and we should really be calling the subatomic particles the atoms and the other thing should be called some kind of compound and it looks like electrons really are indivisible they really are atoms and there's a question as to whether they can actually be destroyed or not do you think like quarks and muons be atoms? yes, so what are those? those are particles out of which protons and neutrons are composed so then we go down to this to another collection of qualitatively indivisible entities muons, gluons, quarks and so forth so fine, if those are the indivisible entities then we should probably call those atoms and consider the higher level things to be compounds now the reigning thesis is that those entities are not further divisible and so those are the atoms of the Epicurean theory but then there is this mathematical theory that says well maybe you could come up with an account of how those particles exist by having a theory about n dimensional strings vibrating in n dimensional space on the surface of brains and this sort of thing string theory now there's no empirical evidence whatsoever of a string theory so Epicureans aren't interested in that kind of just mathematical theory but if that were to turn out to be true then we would have an even lower level of indivisible entity that we would have to account for and then we should call that atoms but here's the point is that this idea of treating entities at some ontological level as themselves being primitive, indivisible and we take their qualities and then we explain the qualities that higher level things have based on what combination those things have that general strategy of scientific explanation is exactly the same as Epicurean atomism and every later form of materialism uses exactly the same thesis so for most purposes we can talk about what we even call atoms the elements as being indivisible and unless we're doing subatomic physics and we're talking about accelerating things to incredibly high speeds and forcing them to collide and so forth then we just treat the elements as if they're atoms as if they're indivisible and we talk about how combinations and recombinations give rise to different effects on a molecular or higher levels so that's just a terminological point now to I have a question I was wondering if bodies are supposed to exist objectively but they're all made of the exact same parts how did one body, like how did you draw the limit besides just the subjective perception between one body and one body because the atoms have an infinite or an indefinite not infinite technically but an indefinite variety of shapes so some atoms are pyramidal shaped and some are in the shape of cubes and others are in the shape of spheres and others are irregular shapes some of them have hooks some of them have eyelids and this is how some of them become entangled with others others are very difficult to become entangled some get trapped within larger structures of entanglement and things like that and so all of the variety of phenomena we see have to do with those qualities but the atoms themselves the only intrinsic properties they have are size shape hardness which is just another term for talking about their indivisibility you can't penetrate into them as it were infinitely hard and also they have this controversial quality of weight or gravity which I'll say more about in due course but the main qualities that they have are size and in the Epicurean view they are all very small so that still gives a lot of range for different sizes they're all below the threshold of our visual perception but some of them are bigger some of them are smaller and then there's an indefinitely large number of variations there but yes if all of the atoms were of exactly the same shape or something then we would not expect to have such a variety of phenomena it would all be a lot more regular because the atoms themselves would be would be regular now a bit more about their cosmology the universe is unlimited and infinite in extension limitation implies that you have an extremity but an extremity can only be seen against the background of something else so since the universe has no extremity because the universe contains everything there is so there is nothing else against which there could be a background then it has no limit and since it has no limit unlimited or infinite and they have these clever thought experiments about well suppose you went to the putative extremity of the cosmos and shot an arrow what would happen either the arrow would keep going which shows that isn't actually the limit of the cosmos or it would hit a wall but if it hits a wall what is a wall it has necessarily has two surfaces so there must be some other side of that wall it must continue indefinitely in either case the universe continues matter or void must continue and so it must be infinite now the number of atoms within that infinite void must themselves be infinite and so must the void if either bodies or void were limited absurdities would arise that contradict our sensations so for example if the number of atoms were infinite but the space was limited then there wouldn't be enough room for the atoms the infinite atoms to fit in but if the atoms were limited but the space was infinite then in the infinite expanse of time everything would become dispersed and no compounds could possibly be formed so we assume that the universe essentially consists of alternating patterns of atoms and void and on whatever take the smallest possible level you want the smallest compound body you can come up with it contains atoms and void take the largest structures you want super clusters of galaxies or whatever they consist of atoms and they alternate with void spaces and there are an infinite number of worlds or cosmos within the universe again a world or cosmos is just a temporary envelopment or separation of atoms in a certain region of space so for example our solar system is just a temporary arrangement of atoms here our sun came into existence at a definite point in time the planets came into existence at a certain point of time essentially through some process of particles in a nebula collapsing into a spherical object or whatever but it was essentially atoms and void somehow moving together now some of these worlds are similar to ours we can assume others we can assume are very different so some of the other worlds they say will contain plant life and some of them will contain animal life and some of them will contain human like objects or even humans others will be totally lifeless and there will be nothing but minerals others will be consists only of one kind of mineral every imaginable variation exists in fact it's possible that there are since we're talking about infinity weird things can happen like some other region of the universe could have exactly this combination of atoms where there's people exactly like this sitting here listening to a lecture on Epicurean philosophy somewhere else because all this world is is just the outcome of atoms that have temporarily fallen into this combination that could easily happen again either somewhere else in space or somewhere else in time so that's probably a very disappointing thing to think you could you know end up in exactly this same position again even worse is the idea that it could happen an infinite number of times and probably will yeah within each galaxy is there a limit on like the number of atoms in the universe is unlimited but is there a limit in each I guess except thank you their theory has resources to talk about that so I mean they're really trying to explain why our visible portion of the cosmos looks as it does and they don't really have a notion about galaxies or clusters of galaxies or super clusters of galaxies in fact so in a way they are imagining that our visible what's visible to us is our cosmos and the entirety of our cosmos that's basically true there's only one entity you can perceive with the naked eye that lies outside of our galaxy and that's the Andromeda galaxy but that was just perceived as being another star in antiquity but yes they have these theories about once you get compounds of a certain structure then they become tend to become more unstable and vibrating elements within structures tend to break them up and things like that so there presumably is some limit and just as you know solar systems are a certain size galaxies are a certain size but we can keep going up to these higher and higher level structures and you look at something like the picture of the cosmic background radiation which is the most global view we have I mean it essentially it's showing you collections of atoms and void there's relatively thinner spaces that have less matter in them and then there's ones that have more don't get me started on dark matter and dark energy which create a big problem for this theory and as their names indicate are problematic in and of themselves but yes this is the kind of thing they will speculate about but the speculation essentially goes as far as saying well lots of different things are possible and there could be worlds much bigger than ours there could be worlds much smaller than ours there could be micro worlds and just as there could be larger level macro worlds our world could be part of a larger macro world and parts of our world could themselves be conceived of as worlds those are all possibilities and so now all of these move according to three causes and this is the point that I'm going to have to conclude on but it's rather important so the first cause of a body moving is that they all tend to fall downwards due to their weight or gravity so this is one of the intrinsic qualities or properties of atoms is that they have weight and in Epicurus' view weight is the tendency of an object to fall downwards now you may very well ask what does downwards mean in a cosmos it's infinite in all directions that's a complicated problem with their theory that I don't have time to get into right now but it is a problem for them the second cause of atomic motion is due to collisions when they rebound they rebound when atoms collide with each other when they clash with each other they either become interlaced if the hooks and eyelets and that sort of thing are entanglements but any collision that happens means that they sort of bounce away from each other but there is a question here if we hold these first two causes of motion together so we say if we hold the first one that says all bodies all atoms naturally move straight in straight lines downwards due to gravity okay then we should have a world that looks something like this where these are the trajectories of atoms and it's sort of a laminated cosmos where it's just a bunch of atoms falling all at the same speed in the same direction downwards in which case collision of atoms is impossible one atom is never going to catch up to another because they're all moving backward and so they're all moving at exactly the same speed and they're moving in parallel lines straight downwards now we know that in fact atoms must collide because if they didn't collide they couldn't become interlaced and intertwined and they couldn't form composite compound bodies but we can see that there are compound bodies so there must be some third cause of motion that makes collision possible and this for this they introduce the scandalous swerve a random or indeterminate motion that causes an atom to deviate ever so slightly off of this linear downward path and so every once in a while this atom just kind of jumps shit and deviates its downward motion slightly enough in order to collide with this atom now once that collision happens then this atom might be forced to move over and collide with another one that's in this trajectory and you can get this kind of cascading set of motions now how often does the swerve happen many different theories about