 Let's get into Epicurean physics. And what I've got here is a bare outline with hardly any references of the main points I want to make. So as usual, interrupt me at any point in time if you want to ask a question about what I'm saying, or even if you just want to direct my attention to a related point or question that you had arising from the readings. Now, like the other Hellenistic schools, Epicurean philosophy divides, essentially, into logic, physics, and ethics. But the Epicureans really downplay the importance of logic. And they consider, essentially, a part of physics. And they even rename it to a Greek word, cannon, or canonic, which means something like the standard or measure. And they think that we don't need to get too much into logic, and we certainly don't need to be focusing on things like rhetoric and that sort of thing. All we need to do is come up with some standard or measure by which we can discern what's true from what's false. And by which we can discern reasoning and arguments that will relieve us of anxiety and give us tranquility. Now, physics, they actually take to be the starting point of the philosophy, and ethics is the end of the philosophy, both in the pedagogical sense and in the sense of the point of doing physics. So in their view, there is no point in doing physics, and certainly no point of doing logic, which is a mere subdivision of physics, unless it has some positive ethical outcome. So look at these radical statements of Epicureans like this one. Empty is the argument of the philosopher by which no human disease is healed. And the word I've translated there, human disease, could, we could say human pathology or even just human suffering there. So empty is the argument of the philosopher by which no human suffering is relieved. Just as there is no benefit in medicine if it does not drive out bodily diseases, so there is no benefit in philosophy if it does not drive out the disease of the soul. So if getting into this logic and physics does not allow us to get rid of mental illnesses, suffering, pathology, human disease, and diseases of the mind, then it's worthless and should not be pursued. It's only if it does have such an ethical effect that it should be pursued. And specifically, with respect to physics, if our suspicions about meteorological and astronomical phenomena, suspicious, meaning things that we can become superstitious about and think that Zeus is causing thunderbolts and Poseidon is sending storms and things like that or that God created the whole universe or something like that, if we didn't have those kind of suspicions about those kind of phenomena and also death did not trouble us at all and was never anything to us. And if we already knew about the limits of pains and desires and we didn't need to figure that out through science, then we would have no need of natural science and there'd be no point in doing it. So we actually have a completely, as it were, instrumental view of why one should do natural science and why one should pursue physics. Essentially, to create human health, both the body, the health of the body, which we need to know about physics and know about the nature of our bodies and so forth in order to relieve diseases and suffering of it and also for the sake of the soul, which after all, according to this philosophy, is just another kind of body within a body and it also has associated sufferings and pathologies. And these are mostly connected to concerns we have about the natural world, what's caused it, whether it's got any message for us and that sort of thing. But if we didn't have concerns about that and we weren't worried and confused about these kind of things, there'd be no point in doing physics. But as it stands, we are plagued with worries about all of these things and confusions about the true nature of pleasure and so forth. And so we need to do some natural science. And at the beginning of the first letter that you read, or rather of the second letter that you read, he says, since this kind of method of investigating natural things is useful to all those who are concerned with the study of nature, I recommend constant activity in the study of nature and with this kind of activity, more than any, I bring calm to my life. So the object of the philosophy is to bring calm and tranquility and relieve yourself of this anxiety that's plaguing you. And according to Epicurus, studying physics is actually the best way to do that. Not just because it provides you a distraction so you don't think about those other things that bug you, but it tells you something about the nature of reality that's actually reassuring and allows you to avoid some confusions and superstitions that plague life and make it less enjoyable, okay? So that's about the overall division of the philosophy and what parts exist for the sake of others. Now, a little bit more about logic and I got one entire slide on logic only, which is about its relative significance in their philosophy. Logic or canonic, canonic the standard or measure which apprehends criteria that apply to basically three things. First, analysis of words in order to determine what if anything in reality they actually refer to. So for example, the word table, does it actually refer to anything? Well, well, suppose we can all agree it refers to this kind of thing, okay? So table isn't that controversial of a concept but what about things like body or empty or void or time or pleasure or glory or virtue or happiness? Some of these terms might not refer to anything that actually exists in the world in which case we should eliminate them not just from our vocabulary but from our minds entirely. In other cases, they do correspond to something but the objects that they correspond to are different than what we think they actually correspond to. And in some cases, they correspond exactly to what we think they do and their relationship is in a way evident or obvious. The second use of logic is to use our sensations and feelings that we all have immediate access to as a basis for distinguishing things that are evident from things that are not evident. So according to Epicurus, for example, it's evident that pleasure is a good thing if you're wondering if it's a good thing just feel some of it and you'll realize this is a good thing or it's even easier to demonstrate pain. You don't think pain's a bad thing? Let me show you how bad of a thing it is. But it's not evident whether something like glory or honor is that a good thing? Maybe that's actually a bad thing. It's not evident whether it is. It's certainly not as obvious as something like pleasure. And finally, we use logic to make an inference of what is not evident from what is evident. So for example, it's not evident that there is a bunch of empty space or void contained within this desk. But I can actually infer from things that are evident that there must actually be empty space in it because it's actually permeable by certain kinds of substances and so forth which could be demonstrated and those things could be observed and we could see those and the only way we could explain those is that there must be hollows or pores or something within the table. Even though it's not immediately obvious to me, I can infer it from things that must be. Okay, so let's start with the basic principles of the physics and you all were quite right to correct me on don't give us an atomistic picture of the universe like Descartes. It doesn't have any void in it because the universe consists of atoms and void according to that and those are the two basic principles of everything and so actually the best representation of the universe that I can find that most resembles this picture is the actual image of the cosmic background radiation of our own universe because after all it consists of a bunch of void space and a bunch of space filled with bodies in greater or lesser amounts of density. Okay, but the actual starting point of the reasoning about this stuff is just the principle that nothing can be generated out of nothing so nothing can just pop into existence out of nothing and nothing can be completely destroyed so that it entirely disappears. You can break things up maybe into smaller units but you can't break it up so much that all of the material basis for it completely disappears and that should be familiar to you is something like the law of conservation of matter in order to bring new things into existence we need pre-existing material rearranged in some way and in order to bring things out of existence we reduce it back to these two smaller parts before it was assembled but we never completely destroy anything and we never create anything new. Furthermore, we assume that the totality of the universe is the same now as it ever was and ever will be there's nothing outside of the universe so there's no place from which it could change or nothing that could cause it to change in any fundamental way. All that can happen is that the things that exist within it become rearranged and juxtaposed into new and different recombinations and this totality consists of bodies in motion through as I said void or empty space and there is an infinite amount of void space and an infinite number of atoms. Okay, so a little more about bodies and void the existence of bodies is evident through sense perception like you've got one yourself and you can perceive a bunch of other bodies in here and not just people's bodies but inorganic bodies so I can see I've got some kind of bodies here and it's resistant to my touch I can not just see it but I can hear it, I can feel it I won't do this but I can taste it if I wanted to and it's pretty obvious that there's a body there, yeah. I was back in the last slide I was wondering how do we know? Let me get to that in a second after I introduce these. Good questions and also how do we know the void is infinite and I'll come back to that in a minute but first of all how do we even know there's bodies or void and the point is that it is obvious or evident that there are bodies, to our very sensation we can tell there are bodies and every mode of sensation reveals there are bodies in fact sensation is just some sort of collision of bodies but the existence of void isn't evident we don't see void as it were it's just empty space but it can be inferred from the fact that there are bodies in motion if there wasn't any void then there wouldn't be any space for bodies to move in and so everything would be immobile but through our immediate sensation we see that things are moving so we know there must be void spaces that they're moving in therefore we have exactly two basic principles, body and void now go back to this slide why do I say there's an infinite amount of void space and an infinite number of atoms? Well, one way to get at this is that we could talk about how we would limit the amount of void or the amount of atoms and then how those two would exist together now suppose there were an infinite number of atoms but a limited amount of void space well then that infinite number of atoms couldn't fit into that limited void space if there was an infinite amount of void space but a limited number of atoms then in the fullness of time all of those atoms would become dispersed in that infinite space and none of them could combine into the kind of bodies that we see and that are visible so if the two options are that void is either limited or unlimited then it must be unlimited in order to accommodate atoms but the atoms themselves must be infinitely many or else eventually they would disperse in this infinite void space now we can also realize that there can't be any limit on the overall universe because the idea of a limit depends on the idea of a kind of boundary but a boundary only exists against some kind of backdrop and so that backdrop itself has to exist in a sense and if it exists then it's part of the universe so for example if I want to say the universe is limited let's just take a simple case where it's a circle or a sphere and then this is the limit of my universe but how do I know that's the limit of my universe? Well I said it was but then it's against this background so I can only see that that's a limit by realizing there's this background that it's set against but then this background must exist in order to apprehend that limit furthermore what happens if I travel to the limit of this universe and then throw a sphere in this direction well it either keeps going in which case there's more void for it to enter and I can apply that argument at any point at any further point and thus it must infinitely extend or it hits up against a wall but a wall is a three-dimensional object that there has to be a certain depth to and then back side to and that's either infinite or limited if it's infinite again the universe is infinite if it's limited then it must have some other extremity or limiting point and the same considerations apply so it's just a matter of there's no sufficient way to limit the cosmos or limit the universe cosmos is a different story worlds are a different story but there's no way to limit the totality of everything yeah so do they think that the soul was just naturally occurring thing that yes they did but we're a long ways from talking about the soul because we haven't even talked about how atoms get combined to form anything or how much less how a living thing could be understood to be a collection or a composite of atoms so we're not we're just not there yet we're we're still just talking about the very basic the most basic principles that must exist anywhere in the in the universe so I haven't talked about how worlds, how heavenly bodies, how stars, how suns, how plants humans animals minerals, I haven't gotten into how any of that exists these are just the basic principles that will be necessary in order to explain any of that stuff yeah the first and the last points sound sort of contradictory to me because you have an infinite number of atoms but you can also say that nothing is created out of nothing they're not they're not created right they're not created but they're not created but there's an infinite number of them yes they well where do they come from they they come you mean like where do these atoms come from right they came from some other part of the cosmos that they that they flowed into and they they've always the presupposition is that there's always been an infinite number they've always been in constant motion in this infinite void that's going to be our basis for explaining everything else and so it's a good question well where did those come from right but the answer is that those didn't come from anywhere everything else comes from them you see not everything can have a cause and that's because some things have to be causes okay and so atoms and void don't have a cause that brought them into existence everything else that comes into existence is a result of their being in existence and there being a recombination of these if we always had to say that everything that came into being always has some prior cause that this will be a vicious infinite regression where we'll never be able to explain anything whereas this is not a vicious infinite regression we're just pausing there's an infinite number of entities and there's no reason to limit them but they give us a handle on causal explanations so I will in theory be able to explain how worlds, how heavenly bodies, how plants, animals and humans come into existence by talking about recombinations of these principles atoms and void okay but they do not come into or go out of existence and so they do not violate this law of conservation of matter there's always exactly the same number of them an infinite number and there's always exactly the same amount of void an infinite number no new void comes into existence which it might be the case that new voids do come into existence like this crazy idea about the expansion of the universe which is actually a standard idea now the epicurians are wrong the whole universe is expanding which means there's more space between everything like there's more space between you and me right now than there was a minute ago that space has itself expanded I mean it's too little for it to make much difference to us now but in 100 billion years even if we just remain stationary space itself would increase and we would end up further apart according to this crazy modern period now that doesn't happen according to epicureanism new void doesn't come doesn't come in new atoms don't come in they might come into a specific isolated world but they don't come into the universe as a whole alright other questions? I'm delighted with these these questions this is what you should be asking now the void doesn't have any properties whatsoever except unless you want to call a property that it always yields to a body passing through it so it offers no resistance whatsoever to bodies and atoms only have a couple of intrinsic properties size, shape, hardness which just means they cannot be divided they can't be cut up any further if they could they could be destroyed and then you could destroy things into nothing but that's impossible so at some point you destroy things into nothing you get down to the atoms or the indivisible entities that it consists of and those atoms themselves only have size, shape and weight basically does void have movement or is it just atoms that have movement? it's just atoms that have movement through the void the void is a condition for their for their moving but it doesn't exert influence or something on them now there is I did notice this morning re-reading this on the bus there's a strange where he says they move because of the void which makes it sound like somehow the void is providing a motive power for them to move but that's not what he means he means the void makes it possible for there to be motion for there to be space in which they they move okay now according to Epicurus and he differs go ahead how do they come up with all these shapes of the atoms do they know that atoms like fire atoms are trying this? well this goes back to democratists as well who speculated about this but for example fire is able to break up other bodies and very much more efficiently than other things so it must be it must have these points be very pointed and then so that it can take even small objects and drive them further apart and create larger voids between them so then it must have the most pointed shape that's essentially a pyramidal shape whereas atoms of other things like of smooth things or rapidly moving things must have a shape that is not immobile like a cube but is more like a sphere because spheres move much more quickly whereas immobile things like earth or stone or something must be made primarily of atoms that are sort of like cubicle or something and that don't have a tendency to move so they make extrapolations about what shapes what various shapes they must have now the most general thing they must say about shapes of atoms is that they they have such different shapes that they can become interlaced with each other and combined and connected with each other if they were all spheres that might not be possible there's no way that they could become entangled and so there wouldn't end up being any compounds but since there are compounds of these they must have to some extent interlocking shapes or an ability to interlock and so the main thing we need is hooked atoms that these hooks can interact with eyelid features on other kinds of atoms so that they become intertwined but we make inferences from sensible qualities things like speed and smoothness and roughness and so forth to the kinds of atoms that the bodies are made out of and democrat has said there's an infinite variation in the shapes but epicurus changed the doctrine slightly and said there's an innumerable or uncountable many variations of shapes but they aren't infinite because he thought if you have an infinite variety of shapes then you would have to have an infinite sizes because you would get there's only so many combinations that can fit into one size and then so you would need bigger and bigger atoms and eventually you would have if you have infinitely many you would have atoms that are the size of whole worlds or you would have at least visible atoms and the atoms themselves aren't visible so a little bit more about compounds so among bodies some are compounds some are simple the simple ones the indivisible entities so compounds consist of combinations of atoms and so they are divisible and we can break up these compounds because we can break them up into their atoms and we can assume degrees of complexity not just atoms but combining atoms into like molecular like structures and molecular like structures into larger and larger structures and more and more complex structures compounds include everything we see in the world all the artifacts like tables and chairs all the plants animals etc are compounds of atoms and void again atoms can't be destroyed because if they could be destroyed then everything could be destroyed and in the fullness of time nothing would exist and we would violate the laws of conservation of matter by the way that diagram there is a bit hard to read the description but was scientists taking an atom taking some iron and differentiating the taking some composite of a metal and then determining actual ratio of atom of iron and platinum atoms within it and making a sort of map of a compound of a chunk of metal consisting of those atomic elements and actually being able to diagram out how they recombined something Epicureans certainly could not do ok now I've already said the universe is unlimited or infinite in extension given the reason for that limitation implies extremity etc I've already said that the universe consists of infinite number of atoms in an infinite void and how there would be problems if you tried to limit either of those so the universe is infinite everything else is limited and there are an infinite plurality of worlds or cosmos of cosmos within the universe all a world is is a temporary of some atoms in a void space and again this can happen on any number of levels we can have micro a micro cosmos or a micro world on a very small level we can have very large and complex things that include entire say solar systems galaxies super clusters of galaxies and possibly even larger structures and they speculate that some of these worlds are very similar to ours some are very different some of them are lifeless some of them have other living things some of them have living things but not intelligent living things others of them have intelligent living things in fact others of them will have things that look like humans in fact others of them will have things that look like humans a lot like us humans sitting in a classroom studying something a lot like Epicureanism and that's because since there's an infinite number of these worlds every possible combination does occur somewhere and then every possible variation on it must occur somewhere so if you think it's really a bad problem that you're sitting here right now you're actually sitting here with an infinite number of other worlds as well but you're also doing an infinite number of other things in other places at other times so if that's consolation for you then good these worlds come into being and then go out of being like every other compound right our world just happens to be this temporary envelopment and juxtaposition of atoms came into being at a certain point of time the star that we're circling around came into being at a certain point of time this planet came into being at a certain point in time the moon came into being at a certain point in time animal life came into being on the planet at a certain point in time and just as surely all of it will be broken up and disappear and dissipate into other regions of the universe and then recombine in other ways now talking about basic causes of motion yeah how did the view of time well they basically neither they have an extremely presentist view of time so only what exists right now in whatever period now is which presents some difficulties should have asked Blythe about this but they things in the past and the future don't as such exist so only present things really exist there's a lot more to be said about their theory of time but in order to explain it I have to explain the theory of motion because time is related to their account of motion so again everybody's trying to jump ahead to explain how the world works and how consciousness works and how plants and animals work but I haven't even explained to you how atoms move in this void yet so let's let's comprehend that so one cause of their motion is the fact that they have weight or gravity and this is an extremely problematic notion actually as it is for us nobody's figured out what gravity is yet but it's some kind of cause that makes bodies fall downwards and fall straight downwards and you can observe this sensibly by doing things like dropping stones or dropping your pen and watching it travel straight in a downward line that's the natural direction that everything tends to travel another cause of motion is that when atoms collide or combine then they rebound and redound in different directions based on based on the speed that they're moving and the shapes of the atoms involved and the angles of their collision then they go off in all sorts of directions and collide but there's a problem if all bodies are naturally moving straight downwards then they're all moving in parallel lines and so how could they ever combine and if they don't ever combine then no compounds are formed and so no worlds no planets no living things no humans but we can see that all these things exist so they must combine somehow but how do they combine the motion of everything is just to move straight downwards when we drop a pen we don't ever see it float upwards or sideways or something so how do we get these we have to posit that there's some other cause of motion and this we call the swerve that there's some kind of random or indeterminate motion that atoms make that we can't account for occasionally one just swerves off this directly trajectory so that it can collide with other atoms so that those atoms can become interlaced and so that compounds can arise so we have to posit that again we can't explain the swerve if you say what's the principle of something swerving I can't I have to posit it in order to explain other phenomena like compound bodies and so on okay so those are the three basic causes of motion they have some sort of natural motion in a certain direction which we conventionally call downwards they have the various kinds of motion they make due to trajectories that happen as a result of them colliding and then in order to get collisions off the ground we have to posit that there's some indeterminacy in this whole system so that we can't always predict the trajectory of an atom and we have to suppose that there is occasionally a swerve of atoms now there must be questions about that point the scandalous swerve this uncaused motion that seems totally unreasonable it doesn't make any sense and we would never believe anything like that there's indeterminacy in atomic motions right we couldn't accept that that was possible you must always be able to determine the space of an atom if you know enough about its direction and its shape and trajectory and so forth right well no it turns out there's this is actually this actually turns out to be a thesis in our own contemporary physics and quantum mechanics that there is indeterminacy in any given physical system now it is not clear for epicureanism how often swerves have to happen one and almost every answer is defended in the scholarly literature so in according to one theory you only need one swerve to have ever happened in the entire history of the universe that was enough to cause a chain reaction of colliding events that got the whole compound of atoms going another possibility is that swerves happen all the time they're constantly happening in fact every time a human decision or something is made there must be a swerve taking a body off of its straight trajectory but that's a complexity we'll get into later yeah what the advent of quantum computing aren't we able to go to simulated environments to answer these theoretical questions like aren't we doing things now that are better able to validate from a more scientific more actionable manner well I hope so I hope that after 25 years 2500 years we can do it a little bit better yeah so the answer is yes I think we do have a better more sophisticated theory of atomism but we still have the a principle of quantum mechanics called indeterminacy and no we're not advanced enough that we've gotten over that so we still essentially have a swerve in our atomic theory we can't explain it it's a phenomenon that must exist but we can't we can't explain it in fact we use it to explain other things but yes these are all real pictures that's a picture of an atomic collision a simulation of an atomic collision happening in a particle accelerator this is actually a map of atoms in an actual piece of metal Epicureans didn't have anything like this they had words written down on paper based on just speculation about these things they didn't have they didn't even have microscopes or telescopes okay so the theory that there's something outside of the visible world that we can see Aristotle looks out at it and says oh it's bounded by that set of fixed stars that always stays in the same relation to each other there's nothing outside of that can't see anything outside of that be totally irrational to think there's anything outside of that well according to Epicureans reasoning a bit differently well could it really be limited what would be on the other side of it what would happen if I went to the edge of it of this sphere and so forth reasoned that it must be infinite okay now by the way the verdict on that still out is it infinite or is it limited did it come into being in a certain point of time or didn't it like none of that has been definitively answered so I mean of course our physics has advanced and I think it's advanced largely along these lines of Epicurean physics but it hasn't what's astounding is how much of this original version of the theory persists within the system like unbelievably much and so that it seems incredible that this could have been speculated about in antiquity and yet it was so we finally get to the burning question that everybody's having how do we get living things out of this and the Greek form of that question is how do you get a psyche out of that psyche meaning a principle that differentiates between a lifeless body like a stone and a living body like a plant or an animal and the answer is that souls are just kinds of bodies certain configuration of extremely small interlaced atoms there is some material recombination of things within a body which will animate that particular body and so there's no you know sort of spirit or ghost or something that's within these bodies because those don't exist there's only atoms and void and so ultimately the brain and everything else in the body if we analyze it enough when we break it up into its simpler components ultimately we're just going to reach these atoms or subatomic particles or whatever but eventually we're going to reach indivisible entities and living things are just really complex recombinations of those so complex that Epicureanism doesn't have that much more of a story to tell about how we get living things out of that but then again neither does our physics still remains a problem we can't exactly answer how do we get life out of inorganic entities so we've been trying to do it for a long time in fact there's lots of great research on this going on here at UCSD can we simulate environments that existed 3 billion years ago on earth when life started evolving here and so we put all these organic and inorganic or we put these inorganic molecules together and we add electricity and so forth we still can't do it we still can't produce living things out of it we can't explain how that happened we have theories about how it happened about how biogenesis happened and they all are theories along Epicurean lines that certain kinds of atoms or complexes of atoms called molecules RNA and so forth combined in these primordial suits and eventually produce something living but we are still unable to confirm that that is how life came into existence and part of the problem is that the only place we've found that it ever existed is on this one particular planet so until we find it on some other one we don't have anything to compare it to and it will be hard to say or it will be hard to say that it didn't say originate in some other part of the of the cosmos and just travel to here 3 billion years ago travel either randomly because some comet or something brought it or deliberately that some other advanced civilizations sent the basic biological material to our world that has enabled it to evolve since then sounds crazy and I wish I could rule one of those theories out and say here's exactly how life comes into being out of lifeless atoms but we don't have that explanation there isn't a satisfactory scientific explanation for that but nevertheless we assume that something like that happened something like the Epicurean story must be on to the right unless you want to think that it's through this panspermia scenario that it originated elsewhere in the cosmos of course the Epicurean line of reasoning about that is suppose it did originate somewhere else in the cosmos well let's go there and then ask how it originated there how did it get started there presumably through some kind of recombination of inorganic atoms in primordial super whatever otherwise it got there because intelligent people put it together but then the question is how did they get there and they must have got there through recombination of things that already existed and so on and so that answer that it originated somewhere else may or may not be true but it doesn't get us to the basic question of where does it come from and why is it there instead of not being there now one thing about living things and about the soul the principle that makes some bodies alive and others not is that soul atoms can affect other bodily atoms and bodily atoms can affect soul atoms and that is why they must all be conceived as some kind of body because only bodies can affect other bodies so I can affect these bodies in my hand by moving my hand and so I'm moving bodies by doing this I can also be affected by other moving bodies like they can collide with me and that's actually what's happening in sensation individual atoms of course aren't complex enough that they can be alive or they can sense these are very complex compounds of them but when these complexes are destroyed or die this is the reason you can't go on to sense anything after you die because you don't have the right configuration or pattern of these atoms that make it possible either to be alive or to sense plants and animals they have got an account that contains some elements of a theory of evolution living things are just recombinations of these more complex parts these atoms combine to form these molecules these inorganic molecules combine to form these organic molecules the organic molecules combine in various ways that give rise to other things in fact things capable themselves of reproducing complex structures and taking other things like food from the environment and converting it into things by means of which they can grow, reproduce, etc and according to their theory basically they again have this combinatorial theory every combination happens that it's possible has happened in our world but only some of these combinations are actually viable and able to survive and among the combinations that are viable and able to survive are the plants and animals that have survived and are around so it's just by virtue of the fact that we are more able to survive in the environment that happens to have been created that just because we have organs that happen to be adapted to allowing us to survive and the ones that weren't able to survive went extinct that makes it look like somebody designed us to be very well adapted for this environment but the fact of the matter is that we just got lucky that our combinations are able to survive in this environment and many other almost infinitely many other combinations that weren't able to survive