Presocratic Philosophy

okay so welcome to week two of my online philosophy course today what we're going to talk about are the pre excuse me the pre-socratic philosophers but before we do that I want to say something about the various ways that philosophers categorize the history of their subject because what we're gonna be talking about is called ancient philosophy but of course there are other periods so you recall this timeline from the first lecture we started talking about the origins of civilization with writing we talked about the origins of Western philosophy in particular with fail ease where they Lee's was interested in trying to discover by careful reasoning and observation the way that reality really worked are the rules which governed it and he postulated a single substance which was the source of everything else which underwent transformations and makanda things that we saw around us in the in the natural world but that underlying that was a single substance and of course he wasn't the first person ever to think that somehow underneath reality is composed of a single substance but he was the first person we know of to offer reasons for that based on observation of the natural world and what you might take to be contradictory so now I say that's the beginning of Western philosophy and usually we date the origins of ancient philosophy there as well and ancient philosophy typically extends sometime after year one by a few hundred years of course depending on who you talk to you're going to get different answers about when exactly this period ends some people date it with a certain particular philosopher other people data with a general event in the history back then so I say 500 years after year one here that's sort of the farthest out but there's people who goes earliest 303 forty-nine it depends on who you talk to but roughly we don't need to be real precise and and in an introductory course like this give you a rough sense of when the period of history is that people are talking about when they refer to ancient philosophy after ancient philosophy we enter the period which is known as medieval philosophy sometimes people think the word medieval sounds interesting and exciting but really it's just a fancy way of saying middle so this is before the modern period and after the ancient period and so just the middle period and that's where medieval comes from and so that's again some time after the end of the ancient period depending on who you talk to they date it to various places or to various thinkers or various events but sometime like 600 years after year 1 500 depending again on how you do this all the way up until roughly the fifteen hundreds when the Renaissance begins to begin and again different people will date this in different ways but then the next period is what we refer to as the modern period in philosophy and sometimes people find it a bit odd that modern philosophy begins in the 1600s or 1500s and extends only till the 1800s and that doesn't seem very modern to people when when you hear modern you might think you know 70s or 60s or 20s or depending on when how old you are but when we say modern in philosophy we mean stuff that happened roughly between 1600 and 1800 after year one and the reason for that is because this is really when modern science as we know it begins and our modern way of thinking about the world is really taking off and of course we've made a lot of progress on that way of thinking but that's where it starts and the reason why it's modern it's because it's throwing off the the way of thinking about the world which was developed in the ancient and medieval period so we're gonna go through this timeline here we'll start and spend 1/3 of the class in the ancient period and then we're gonna skip the medieval period and that's not because it's not interesting it's just because there's a lot of stuff to cover and something has to give and most scholars up until very recently actually have sort of viewed medieval period as merely the Christianizing or muslin izing of the ancients so that what you get is you know Plato interpreted through Christianity or Aristotle interpreted through Christianity and of course that attitude is probably not entirely correct and recently people have began to look back at the medieval period and have noticed striking similarities to what people are thinking about even currently so I think there's a rediscovery of this area but we're still going to give it a little bit of a short shrift in in this series of lectures although I do talk about people from this area more fully in my philosophy of religion course and that's again because you find a lot of people making the traditional arguments for the existence of God in dealing with the kinds of problems of philosophical theology so we won't really be discussing that in this class so then we'll go to the modern period and spend a lot of time there and then finally we'll end looking at the present period which comes after modern and depending on who you talk to it can be variously called the post modern period for people who are members of one tradition known as continental philosophies roughly if you look at the map of Europe and England is an island then the Continentals are those who were not on the island of England so for France and Germany mostly and the Continental thinkers have a certain view we won't be talking much about that because that's not my area of expertise I'm trained in the other area which is sometimes referred to as analytic philosophy and analytic philosophy has an emphasis on clear reasoning and logic and so often you'll notice that I tend to fall into that category but mostly we will refer to the present period as the contemporary period and that generally takes 1800s until current day and by the time we're done with these lectures we'll be looking at people who are currently alive or at least not to sound too morbid but they are alive at the recording of this lecture series okay so let's go ahead then that's a brief overview of the various periods the history of philosophy let's go ahead and look a little bit closer at the period that we're gonna be starting with which is the ancient period and really only the first 400 years of that as I said it goes on after this so until the year one and then even extending into the Common Era but we've already talked extensively about bailey's as the being getting credit at least for being the first Western philosophers first person to take this kind of approach to answering these questions so we won't really talk too much more about Bailey's I want to talk generally would give you some landmarks of where and the people we're gonna be talking about fall in the timeline so we're gonna spend some time talking about Parmenides who was a major influence in a very mysterious figure and you know there's a lot of debate about what he really meant but either way he's become very influential so he was born roughly in five hundred and ten years before year one and he lives to 450 so overlapping then with Socrates who of course is a very important figure in Western philosophy and so the week three is devoted entirely to Socrates so I won't talk too much about Socrates in these lectures now Socrates is most famous student was Plato and Plato lives from 427 to 347 so he would not have it's not possible for him to have met Parmenides but he's and Socrates had other students but plato was the most famous than them and we'll talk give a whole section a whole week devoted to the views of Plato and then Aristotle was the student of Plato and Plato again had many students but Aristotle wasn't the most famous of these and so in some sense the goal of this first section on ancient philosophy is to work our way up to understanding Aristotle's views because he comes to have enormous influence in the world in his way of thinking about the world become underwrites the way that learned persons thought the world operated for all the way till the modern period and in some sense might not be an over exaggeration to say that what's modern about the modern period is that it overthrows this earlier way of looking at the world that had come to dominate which was started by Aristotle so that's gonna be a kind of theme that we're gonna be working up to okay so let's go ahead and start now the period of philosophy that we're gonna be really focused on in this first lecture is what is known as the pre-socratic period in philosophy and I haven't really said why that is but you can see already that it must have something to do with Socrates and it's true because he's such an important figure in the narrative that his Western philosophy that we divide this period of time ancient philosophy into the classical thinkers who come after Socrates mostly historically at the time that's when this term was coined in the 60s and 70s that's what they thought and the pre-socratics now the pre-socratics are usually exemplified by fail ease and the other Ionian philosophers who were in my Letus if you recall from the first lecture so these Ionians over there had a certain way of thinking about the world and a certain approach but it also as you will see includes Italian philosophers such as Zeno and Parmenides who were not themselves Greeks but were from around the corner and had important contributions to make but also more interestingly we'll notice as well that some of the people who are termed pre Socratic were actually alive at the same time as Socrates so you could see from the timeline earlier Parmenides would have been very old when Socrates is very young and there's no reason to think that they met historically although there is a dialogue by Plato called the Parmenides where he relates a dialogue between a character named Harmony's and Socrates though it's widely agreed by people who work in this area that it doesn't actually reflect a real discussion had by Socrates it's at least excuse me it's at least possible that something like that could have happened given that Parmenides would have been very old when Socrates was very young so nonetheless though we refer to Parmenides as a pre-socratic philosopher even though he might have overlapped and we'll see other philosophers who overlap more fully with Socrates so the reason you had to do more with the style and the questions that are dealt with then being before or after Socrates okay so give you some now of course in an intro class like this we can't really go into as much detail and complexity about these pre-socratics as we would like to and you can take an entire course on this if you're interested but I want to give you some flavor of the kinds of ideas that were talked about and the arguments that were given for them give you some appreciation of the immense kind of intellectual fertility which was present amongst these early Greek thinkers so we'll start with a guy and of course I can't mention them all so I'll pick there's a there's an enormous range of people and personalities which are all interesting so I'll try to pick a few so Anaximander a very important one and you could see born in 610 dies in 546 it's rumored that he was a student of Baileys although again we're not a thousand percent sure that this is true but the the history of this era certainly linked these two guys to each other and he was also rumored to have been the teacher of Pythagoras although if you look at the actual dates involved he must have Anaximander must have been relatively old and permit excuse me Pythagoras must have been relatively young but it's nonetheless certainly possible that he was the teacher of Pythagoras and he again like the other my lesions and Ionian philosophers thought that there was a single substance from which everything else was made but rather than picking one of the elements which various other persons so for instance remember recall that they Lee's argued that it was water and that water underwent these state transformations and could become very compressed and be like wood and become very when it turns into vapor it's like water makes clouds and etc what Anaximander thought was something which he in the Greek called the aperian which we can sort of translate as the unbounded so what he thought of it as a kind of formless uber substance which could take on the attributes of anything in the physical world and which ultimately was used in the making of the things like earth and air and water and fire and then everything else was made out of that so that's a very interesting idea and very difficult idea so now we can mention mention another one and examinees who was the student of Anaximander so these guys all were in my latest arguing about what the most fundamental substance was that that everything else was made out of and an examinees associated the elements air with with life and you can kind of see why when people are living they breathe and they require oxygen and well they didn't wouldn't have called it oxygen obviously but you require air as they would have called it to stay alive and when you die that goes away and often people thought you have a dying breath and that was the last bit of air or soul coming out of you so an examinees identified air as the most divine of the substances and thought that it was the RK which means source or original principle out of which everything else derives so here you have the basic elements you have dailies claiming that water is the most basic you have and examinees claiming that air is and will meet other people who claim the fire is the most basic element because life is associate with heat a dead body is cold a living body is warm so they were making these various associations trying to figure out what the most basic thing out of which everything else was built and then the interesting idea of Anaximander that it's some kind of a period or unbounded thing which then becomes the source of all the bounded things that we have and there are other host of interesting ideas that in arguments which these guys talked about so for instance an examinees is the first person actually talk about how it is that you can change one thing into another so he talked about compactification which actually and interestingly he was analogizing to the process of making felt which apparently felt is just taking wool and pressing it really hard compacting it and you get something which has completely unique properties which are very different from the wool so - and examinees argued much like that you can take air and compress it and you get first of all water and secondly earth and then finally something very hard stone and then when you go the other way when you rarefied thinning it out stretching it it becomes fire so that air could turn into these other basic elements according to an examinees so now this is into what we think and we don't think that any of these are true but there are all very interesting ideas and excuse me and notice that they are trying to support them with observations from the physical world and by reasoning about the basic structures which could give rise to other things all right so would that we could spend more time on those pre-socratics but I want to focus more fully on Parmenides who i've mentioned already and i'll contrast Parmenides with Heraclitus just to give the flavor so we'll say a bit more but the basic idea that Parmenides had was expressed in a poem so he didn't write essays he didn't write prose and his he wrote a story which was in complicated meter was called hexameter which actually has so if you think of poems they have definite structures and this was written in one poetic structure which related a goddess revealing to a mortal the way of truth and the way of mortals so there's making this distinction between what people sort of averagely thought and then what really is and this is an important idea in and of itself because what Parmenides is drawing our attention to is the distinction between the way the world appears to us and the way the world really is so what an appearance and reality distinction and this is one of the was already present obviously in the dailies and an accent and examinees and then I can enact samandar so they were already saying that the world which seems to be various is actually at a more fundamental level unified so that the way our appearance of the world doesn't really map the way it actually is so now Parmenides is bringing this out again and it was often tooken in in the ancient world and in by scholars that the point that Parmenides was trying to make was that the appearance of many things in the world as being many that there's trees tables chairs the moon the earth the stars people moving around was somehow an illusion and that at a deeper level everything was one and this is not a universally accepted interpretation of what Parmenides was up to but it's the one that helps to put this whole debate in the ancient world into some kind of context and Parmenides views are contrasted with Heraclitus who was a well-known figure in the ancient world but who's probably most well known for his views that the only thing which never changes is that things always change so people would say oh that's very interesting changes the only unchanging thing and you can see sort of what Heraclitus is trying to say which is that everything is in flux nothing is stable so famously for instance he says you cannot put your foot into the same river twice because the water is ever rushing on and on so in short you put your foot in the water you take it out by the time you put your foot back in there's new water there it's a different River it's not exactly the same River and so the world is like that on a massive scale everything is coming and going and nothing is standing still for very long and so the only thing that we could really know about the world was about everything was changing and Heraclitus had this idea that what we really needed to do was figure out what the rules were which governed those massive changes out there and of course he wasn't entirely consistent and people debate about what he meant but we can see a kind of contrast here between people who think that really at bottom all the changes which appear to us are unified as some more fundamental level by something which is unchanging and those on the other side who think well the world is just constantly in this flux and that's what really is real so we'll look at some of the arguments that Parmenides gave for this view and of course in the ancient world this was not widely well thought of the idea that changes an illusion and that in reality nothing really changes so we'll look at one of Parmenides students namely Zeno and we'll look at some famous paradoxes what Zeno allegedly reportedly came up with his work on this was lost sadly but we have reports of arguments of his which try to show there's something really seriously problematic and the idea that things change and then finally we'll end this section talking about another ancient pre-socratic named Democritus who is responsible for popularizing and making some arguments for the view that reality is composed of atoms so we'll look at ancient Greek atomism which is very different from the atom ism of our day so that's the plan now what I want to do though to begin with is kind of sum up some overarching themes that we've been talking about so the I think it really helps to understand this whole period if one is thinking in terms of the way that geometry works and I mentioned this in the first lecture but I think it's important to remind ourselves now remember what happens in geometry is you start with a certain basic set of axioms and then you use those axioms to work your way out to things which you didn't know before so for instance Daley's famously showed how you could use geometry to measure the height of very tall objects and he allegedly reportedly did this to the pyramids in Egypt so that if you know the Pythagorean theorem in its basics and if you wait until the time of day when the length of your shadow is equal to your own height then you can measure the shadow that the pyramids cast and then you can measure the angle at the base of the pyramid and then you can calculate actually what the height of the pyramid would be so that this using these basic knowable by reasoned propositions like the parallel postulate like shortest distance between two points is a straight line and there are other ones obviously but these are sort of my slogan ones knowing those things you can then go on and know something about the way the world works you could know that the height of the pyramids was this high and that's something very exciting so what the philosopher then wants to do on this model is to search out some things which are like axioms for the real world in the way that the principles of geometry are and so here are a handful of them which I think underlie a lot of the arguments we'll be looking at in this section and these are supposed to be the kinds of things which you know directly and immediately by the use of reason in a way which the senses don't reveal so let's look at a couple of them so the first is this idea that opposites cannot exist in the same object at the same time think for instance about a square in a circle I've never seen all squares neither of you neither have you seen all circles but yet I'm fairly confident that there are no squares which are also at the very same time circles why do I think that for instance you might think well you know my fly to Jupiter and buried in the Jupiter sand they might dig up this object and the object might be something which was Square and circular maybe it's just you've never seen one before how do you know there aren't any anywhere well the idea is that well you can prove that from this because it follows from this more basic thing which is known about reality which is that you can't have opposites existing at the same place at the same time and if a subject were square and a circle it would have opposite properties for instance it would have four right angles and also no right angles circles have zero right angles and squares have four so the object would have to have both of those properties at the same time that's contradictory or again circles have the property of every point on the circumference being equidistant from the center point where squares don't have that property the corner of a square is further from the center than any point on the parallel lines there so these things don't exist and of course you can extend this to any kind of opposite properties like hot and cold you can't have an object which has both hot and cold and of course unless it's warm you can put sort of heat and cold in the same place and then you get this third thing warmth which is neither really hot nor cold but you can't have something which is extremely hot to the touch and also extremely cold to the touch at the very same place right you could be a bar that's hot on one end and cold on the other but not at one single place you can't have red and green at the same place at the same time and etc so now notice you can't really give an argument for this it's just that you can see with just by thinking that these things are contradictory and that's supposed to tell us something about the way the world operates so here's another one of these things oh I'm sorry I already said that so here's another one of these things and this is a very powerful idea that something can't come from nothing so think that the the basic reasoning behind this principle is fairly simple if there were some object which came from nothing something it would just have popped into existence from nowhere without anything being generating it then we can't explain where the stuff it's composed of showed up from right if it really if there really is nothing at all then you can't produce anything from it because to produce something requires that there is already some stuff there which can be produced and already you can see this kind of idea behind the thinking of people like Faye Lee's and Anaximander that there's got to be some stuff out of which everything around us is ultimately produced because you can't have this stuff just popping into existence without there being something which it's derived from this is principles appeal to over and over again in the ancient world now here's another very powerful idea which gets debated for centuries it turns out but let's just phrase it here in its most intuitive way this is the idea that nothing cannot be something and will in a second see that Parmenides makes a big deal out of this so what is it that they're trying to say here well the idea is supposed to be that emptiness isn't a real thing that if something doesn't exist then it's just not there it's it can't be a kind of entity in itself and of course you cannot sort of see where the contradiction comes from if the nothing existed then you would be forced to say that there was an object a something which was also a no thing and of course that doesn't make any sense now of course behind all of these axioms we can see an overarching uber axiom you might say another axiom which later becomes called becomes known by the name the principle of sufficient reason which is that anything that is out there has to have some kind of explanation for it and this is kind of the overarching background idea and this is something you can just see by reason there's got to be some explanation for it there it's got to be an explanation for why you can't have hot and cold at the same place for why it is that something can't come from nothing or why it is that nothingness can't exist so we have these various basic axioms I think it's helpful to pull them out and make them apparent because they get used and appeal to so now let's look actually look at some of the ways in which these things get applied so we'll start with Parmenides so people debate about what Parmenides actually meant as I've said already but it's generally in the ancient world and in a sort of historically when philosophers were looking back in this period it was widely thought that what he was arguing was that change is impossible and of course there are scholars who debate this and say you should interpret Parmenides this way or that way so this is not universally accepted but it's one way of taking what he said and it's a very standard way of taking what he said so why is change impossible according to him well because it leads to one of these two things it leads to a violation of one of our axioms which we know independently already can't be violated so what Parmenides was trying to show on this interpretation was that if change happens then either something from nothing or you're saying that nothing is something that nothingness exists and we want to deny both of those and you can't give a theory of how change works without violating these already known previously accepted axioms and therefore even though it seems counterintuitive change is merely an illusion it doesn't really happen now before I actually run through this argument it's important to stop for a second and make something very evident Parmenides cannot be refuted by pointing out that you walked to class or that you used to be 5 feet tall and now you're 5 foot 4 in other words you can't refute Parmenides by simply saying things change look around because what Parmenides is is arguing is that there's an illusion of change and to make this vivid think about magic so when you go see David Copperfield and he gets his assistant in a box and saws the box and a half and then splits the box and the top half of the lady is in one place and the bottom half of the lady is in the other place and her feet are moving you cannot and then someone says ah he didn't really cut her in half it's merely an illusion it's not a response to that argument to say but look don't you see there's her feet there's her head so when per minute he says that change is an illusion what he means is that of course it appears to us as though you are a separate thing from the rest of reality or it appears to you as though you walked around in your house today but all the things all of these things are mere illusions mere appearances and he really is taken in this way as denying any kind of change change in place that's movement change in quantity that's amount so you can't be taller than you were that's an illusion it's in some way change in quality so things can't change from hot to cold from red to green and change from destruction or creation that's also a kind of change what they what Aristotle calls generation making something in corruption or it's going out of existence at some point so Parmenides is should be interpreted as denying all of these things as being real so here's the basics of his argument so just take any kind of example of change say that you have a piece of iron that's been heated up and it's glowing red-hot and now it's turned it an hour later it's cold so one mole at one time it's burning red-hot and another time it's cold to the touch what's going on there well we already know that when it was burning red-hot there's no coldness which is existing in the poker and of course you can deduce that from the axiom which we've already accepted that opposites can't exist at the same place so if there's really heat in the poker then the cold can't be in there as well right that would just that just follows from the axiom so cold is non-existent there's nothing in there which is cold but now the trap is sprung because where does the cold come from how does it come into existence if it is non-existence that really was supposed to be the force if it if it if it's non-existent at one point and then it's there the next time well it looks like you got something from nothing because there is nothing there and now you have the something but on the other hand we can't even if you want to say well it didn't come from nowhere there was cold in some sense somewhere already but since we've already agreed that it doesn't exist in the hot object then it looks like you're saying that nothing is something that the coldness is something even when it's not in the object and that doesn't seem to make any sense so it looks like we're led by careful reasoning about what could make change real to the rejection that change is possible now of course there's another way of thinking about Parmenides which is I think a more contemporary way of thinking about what his point was as a purely kind of logical point that well for instance what contemporary philosophers would call the puzzle of non existent objects so I think that Smurfs don't exist or one of my favorite non existent objects it's a vampiric unicorn so unicorns are pretty horses which print surrounds vampires are filthy blood sucking creatures and no one's ever written a story or had a cartoon about a vampiric unicorn but I often think it would be funny because it would be the last thing that you would expect so vampiric unicorns don't exist but if we were right that nothing can't be something then how can I even think about that which isn't that which doesn't exist but clearly I'm thinking about a vampiric unicorn so some people are led to call this the puzzle of non-existent objects which is that in order for us to even say that they don't exist they've got to be there in some sense and this can be sort of summed up by a joke so when someone says vampiric unicorns don't exist someone might respond by saying wait a minute what doesn't exist well vampiric unicorns of course ah but now you're talking about this thing and it seems as though you're referring to it you're thinking about it and so it's got to be out there in some sense so how do we make sense of this without saying that nothing is something that there are these non-existent objects which we talked about so that's a puzzle and it can it follows naturally out of thinking about what Parmenides is talking about here and of course we'll see these ideas sort of ramify through the pre-socratic and ancient world okay so we'll talk about Zeno's paradoxes now and as I've already said Xena was the most famous student of Parmenides and what he did was try to develop several paradoxes to show that motion was impossible and this because he was trying to defend the views of his teacher Parmenides now of course the average person on the street in ancient Greece and in ancient Italy would not have thought that Parmenides views were very serious so they would have thought well look things change my son used to be 10 and now he's 20 so clearly the years have progressed he used to be 3 foot tall now he's 6 foot tall clearly the amount has changed there and he used to have blond hair now he has dark hair so something has changed about his quality the colors and the seasons changed and that the world has just changed so the Heraclitus view would have been the more common sense view but what Zeno wanted to do was to try to argue that it's actually the reverse that the common sense view is full of paradoxes and contradictions so that really we must accept the the view the Parmenides had so he has several of these and he was alleged to have read a book the paradoxes of the plurality as they were sometimes called on the paradoxes of there being many things and we don't have that book it was lost to us but his argument survived there reported by other people and talked about most famously by Aristotle so we'll go through those only a couple of them there are several others and he's famous a story of the hair of Achilles and the hair which gets dramatized in various Bugs Bunny cartoons as The Tortoise and the hare right so the first paradox is that if objects moved says Zeno they would have to cover an infinite distance and this is because well you've taken e2 points say here in the door and there's 10 feet of space in between me and the door you can always have that distance in half so it's a theorem of geometry that you can always divide the space divide a number in half so there's no smallest number you can always divide them into smaller and smaller numbers and so we seem to arrive at this contradiction so here's a common-sense way of putting it in order for me to walk a hundred feet I first have to walk 50 feet but in order to do that I would first have to walk 25 feet but again in order to do that I would first have to walk the 12 and a half feet to the middle there and so on and so on forever so we can kind of dramatize this here there's the distance you're trying to walk between you and the end of the screen there and if you're gonna make it all of that way you first got to get to the half point but of course you can't get to the half point because first you have to get to the halfway point from there and etc and etc and etc so we can kind of put this in the following way there's an infinite distance in between any two given points because the total distance is the sum of all of those infinitely small distances so it's the sum of all the various halves added up together and of course it seems impossible for a finite amount of time to be enough time to accomplish an infinite task so there's doesn't seem if every step that you take is really you crossing an infinite distance then it doesn't seem as though taking one step is enough time to do that and so motion seems to be an illusion here okay so here's the second paradox which is known as the paradox of the arrow and this is very interesting so look at this arrow here and observe so now you saw the arrow move across the screen and let me ask you do the arrow move across the screen now you might think well that's a trick question I just saw the arrow move across the screen but if you know anything about computer graphics you know that you did not see an arrow move across the screen what you saw was unique arrows being flashed briefly at different positions on the screen in a quick enough succession so that you are tricked into thinking it's one object which is moving across the screen as opposed to several different objects which are being flashed and this is the same principle behind the way a movie works a movie is a series of still images which are shown at a certain speed and so when you're sitting in the theater certainly appears as though people are moving around on the screen but no one is moving it's just still images being flashed at an appropriate speed and so the paradox of the arrow is roughly analogous to this way of thinking about reality so if we think about the time between the take a real arrow now not this computer-generated one but an actual arrow and you shoot it at some target it takes a certain amount of time 10 seconds let's say and you can think about that period of time and divide it up into its smallest moments instance the smallest unit of time we can think of time as having these discrete units that you can't get any smaller than and if you do that well then it becomes problematic because at each individual instant of time the arrows in only one location it's either it's never halfway in between two locations it's always at one determinate location an object can't to be partially at a location or partially here and partially there it's got to be right here as xeno puts it it occupies an area which is defined by its outer boundaries it just is in that arrow shaped area of space at any particular instant but now you generate the paradox if at any particular instant the arrow is motionless then how does it move what you have seems to be like in the computer in case a series of still things which over time somehow give you the illusion of motion but they can't really be moving underneath so this we can put it in words at each moment during the arrows flight the arrow itself a stationary much like the end of the vigil frames that make up a motion picture so again what we perceive our best continuous motion is an illusion now notice kind of summing up here both Parmenides and Zeno think that illusionism prevalent and that motion and things we take for granted fall under this category they're not the first thinkers to think that there are various other views of the world as underlying so the world of appearance is some static unitary unchanging stuff but these are the first people to actually try to give arguments which are centered on the avoidance of contradiction on using reason to try to ferret out the way the world really is and this is a theme of this kind of work is that the senses give us the impression of these various things the senses can be mislead reason doesn't get mislead and it tells us the way things really really are now of course apart from that what Zeno's paradox brings up is the very interesting question of whether or not time is continuous or discrete so we often think of time as like a river is it flowing instead of being above these discrete moments but oh it's not exactly clear what the right way to think about time is and one central issue and contemporary philosophical work is trying to get clear on which model of time is right the time of it as the model of it as being continuous of not having smallest parts or the idea of it have being discrete instance which take up no time themselves but which comprise the passage of time now again we're not gonna resolve these issues but I merely bring them up as a way of getting you to think about what these ancient pre-socratic philosophers were interested in now one thing I will mention is that it's often said that modern physics has solved this problem and that even though at each discrete discrete instantaneous moment the arrow is stationary at the next moment it either is in the same place or not and based on what happens next we can assign the arrow at an individual time something which is called instantaneous velocity so and that's just an indication that at the next unit of time the arrow will be in a different position and that instantaneous velocity gives you some way of in determining how far away from its current position the next position will be or to put it more colloquially how fast it's moving so even though at each instant it's stationary we can still say that it's moving but you can't say of any given object that is moving at an instant you have to have a whole series of instants over time in order to be able to say whether an object is moving or not because it is true that each moment it's stationary now that's the kind of modern or contemporary calculus based answer to Zeno's paradox and again I don't think we're gonna resolve these issues but I merely bring this kind of stuff up as a way to try to show that when people were developing calculus when Newton and other people who developed these ideas were working on them what they were they saw themselves as trying to model how change works mathematically and that was something that had been a problem for a very long time so these are very interesting issues and even if you disagree with Parmenides in xeno their ideas help to focus or bring out the requirements for successfully giving a theory of how things change or how motion is possible okay so as an example of that let's look at early Greek atomism because I think it's quite astonishing that the Greeks had something called atomism and modern people when they find this out go oh wow so they knew about the protons and electrons and of course that's not right they have a different version of atomism but it goes the influence goes the other way when modern scientists postulated discovered empirically something that they thought were the basic elements which made stuff up they thought they had discovered what the Greeks called atoms and so there was a resurgence of atomism in the fifteen in 1600s and we'll look a little bit at that as we go through but it's still very different from our version of it but of course it leads to it so it's interesting to see this now well look at one of the main early defenders of atomism a guy named Democritus who had a teacher named Lucius and we sort of give short shrift to poor Lucia Pez and focus on the work of Democritus he's born about 460 and dies about 370 and just to give you some frame of reference Socrates is executed and we'll talk about that in Week three but he's executed in three 99 so Democritus would have been a contemporary of Socrates now the word atom itself comes from the Greek a Tomos and a means not as an asexual not sexual and Tomos means splittable or cuttable so in a Tomos an atom is literally something that is indivisible something that cannot be cut or divided in any further away and the atomists were fond of saying that there were in reality only two things that existed atoms and the void so atoms are hard and what they mean by calling them hard is simply that they do not form a blob when they bump into each other so there are some things which like drops of water if we take two drops of water and smush them into each other they become a bigger drop of water but an atom is not like that it bumps off of the other atom much like a billiard ball a pool ball will bump off another ball now they move around in the void which the model as empty space and so already there's a controversy here because Democritus does assert that nothing is something and he very self-consciously says look the void has to exist and he thinks that it's the only way that motion could be possible so how could anything move if there was an empty space in between the little atoms so the idea that Democritus has is you can sort of picture it metaphorically like this imagine a bunch of legos and they're just flying around in space bumping into each other these legos have little joints and hooks and parts and of course they fit together in various ways and over time a massive milling about these things will form clumps and then they'll form bigger clumps and there's an endless number of them and ultimately everything around us is composed out of those tiny little LEGO pieces which are every size and shape and orientation and flying around in an endless endless cycle now atoms are themselves unchangeable so any given particular atom is always that way it always was that way according to Democritus atoms are never created and never destroyed and notice that this is similar but different from the views of Thalys and the other my lesions since they argued that there was a basic stuff out of which everything else came from but they thought of that basic stuff as something like an elements like water or fire whereas Democritus is here claiming that fire is itself made up out of atoms a special kind of atom and so is water and so is Earth and so is air and so is the human body and so is the spirit and everything around us the Stars the moon all of those things are actually made up of these tiny indivisible unchangeable undestroyed ball things buzzing around forever okay so now why would you think that well first of all here's a thought experiment so it's suggested by Aristotle that Democritus thought well you know suppose that you thought that matter was infinitely divisible then you could carry that out there does seem to be an assumption on this part that you could complete an infinite task and that this made sense the question then for him was what would be left over when you were done and often it was thought well you know matter was ultimately devised about forever and that what was left over was something it was kind of like a fine dust but I had to be something couldn't be nothing right because if you could chop it up into small enough parts and eventually get to the point where there was nothing then you would be saying that all the objects around us are made of nothing ultimately that there at the bottom nothing there's got to be something that's left over but of course if it's left over it's not divisible because we've already stipulated that you divided it as much as possible so there seems to be a kind of conceptual argument that there's got to be something which is at the bottom which can't be any smaller some basic physical element attributes what just nothing can be smaller than that and that's called the Adham for this for these guys but of course there's also a more practical argument which is simply points out that complex things around us are often made of smaller things and one prime example is the alphabet so this is Aristotle's example what she talks about attributing it to Democritus and these other Adam ist's so here we have letters and from the point of view of a language letters can be thought of as atoms they are basic elements which cannot be chopped up any smaller and of course you can take an A and cut it in half but the thing that you end up with is not a letter so of course they're not really real atoms because it can be chopped physically into smaller segments but from the point of view of a language they are atoms in that you cannot have a smaller element of a language that still counts as itself part of a language so given that you can sort of give an analogy here a and n as letters differ only in their shapes whereas a n and na differ only in their arrangement and other things differ only in their position so this font isn't the best for seeing it but if you take an eye in an H you can and you write them a capital I is kind of an H turned sideways and and so on so that's merely the position which they're oriented and of course another example be n + Z Z is kind of a sideways in and then of course they vary in size so we have little a's and big a's and those signify things now given a basic set of elements which only differ in these set ways we can generate an infinite number of sentences which are infinitely complex in various ways so for instance take a few were letters combine them in the words those words make sentences those sentences make paragraphs those paragraphs make chapters or chapters make books and etc and etc most of the sentences which people have uttered we're new and not produced by people previously so of course you can use stereotype language and you can say hey what's up and how's it going but you can also say sentences like the stripe giraffe sat on the pillar and mocks the surrounding elephants now of course probably no one has ever said but the point is that given this basic set we can make these infinitely new variety complex things so maybe the world works like that maybe the world is simply like a complex paragraph composed out of these smaller parts now this struck many people has quite bizarre because here is Democritus who's arguing that the world around us is the product of chance the way things work given atoms at enough time anything that could be built out of atoms eventually would be built out of atoms they're just bumping into each other and so any possible arrangement of atoms would eventually come to be arranged in that way and so the fact that we exist that human beings are here that the earth is here that the Sun is here that the universe exists all those things are just merely the product of this accidental process of atoms bumping into each other and eventually this world will dissolve in new world worlds will form and Democritus had this idea that it was just this is the way it went there could be many worlds different places where life existed they would go out of existence new ones would form and it was this endless cycle of things coming into being and going out of existence sort of like Heraclitus thoughts but at the bottom is this world of unchangeable little parts which are just constantly being arranged so he's combining elements of the view that per minute he's had that something has to be stable and unchangeable with the view that the world of appearances is constantly changing but it's not an illusion it's real now how could all this complexity they'll come from some random mindless process well interestingly enough Democritus appealed to other mindless random processes which resulted in a kind of order so famously he said look if you go down to the shore and see pebbles arranged by the tide heavier pebbles are further away from the water lighter ones are closer to it and it looks like there's a kind of ordering process there of someone coming and placing smaller ones here bigger ones there but of course that's an accidents a byproduct of this now actual process of this randomness where the heavier things are just carried less distances and lighter ones are carried further away so it looks like they're ordered further lighter things further away but really there's no ordering there it's this random kind of process so that was the view that Parmenides had and it very creative thinker thought well maybe even the gods are like this and the way we perceive is that objects emit these kind of films of atoms that are like kind of like little translucent bubble things and that explains why that they travel through the air they become smaller until the point they can enter your eye that explains how we have visual contact with the world around this by they're emitting these kind of atoms and they affect our eye atoms and you really thought that the soul was made of atoms that human beings were completely physical and that this only thing special about soul atoms was that they were cylindrical so that they could slip around and so he's really a thoroughgoing materialist things there's nothing non-physical about the world nothing mysterious and very interesting how he gets there and we'll see later on that Aristotle really just cannot handle this view and rejects it and and it's rejected until rediscovered empirically much longer okay but so summing all this up then we can see how atom ism is as a development a theoretical point of view gives an answer to the problems that Parmenides and Zeno challenged so per-minute e says look how is this hot thing cold later on something must have come from nothing or nothing must be something and Parmenides presents this as a challenge saying show to me how this can happen without one of the two of these things occurring and Democritus can now answer that challenge he says look nothing I agree with you that something can't come from nothing but really what you have is just a different arrangement of atoms so the same stuff is there but rearranged so you don't get something from nothing it's the same stuff just arranged in a different way just like you can take the word dog and rearrange it and get the word God you haven't got something from nothing you have all the same parts just arranged in a different way and that explains how it is that change could be real in knots and illusion so there's no problem now of course you do have to accept the void that nothing exists and this is something which Parmenides denied was excuse me denied was acceptable and we'll see this is one of the sticking points that Aristotle has as well that he just thinks that nature could not be such that it contained void and that's part of his reason for rejecting atomism but if you accept the void you don't have this problem with change and you don't also have and you also don't have xenos problem as well so Zeno says look you can divide the distances in between any two points infinitely and Democritus says well actually no you can't because there's a smallest element the atom which can't be divided any further so you don't get this weird paradox all you get is that there's a large number of points in between here and there but not an infinite number of points so geometry doesn't really model these that this idea that we can sort of arbitrarily divide as small as we want turns out not to model the way physical reality is according to Democritus that physical reality has a smallest element a smallest unit which can't even not even conceptually can't be divided or cut up any further and so atom ISM is an interesting view as developed as a response to the challenge of Parmenides in Zino and one that doesn't have its day for about a thousand years when people actually invents mechanisms which allow them to see that there are parts around them and develop more powerful theories so we're going to put out a minute um on hold and we'll revisit it when we get to Descartes and look at that stuff but for now I will say thank you and I look forward to seeing you at the next week's lecture

Channel: Richard Brown

Views: 88,002

Rating: 4.8510346 out of 5

Keywords: philosophy, pre-spcratic, thales, zeno, democritus, Zeno Of Citium

Id: zfLgRotdcKI

Length: 62min 1sec (3721 seconds)

Published: Tue Sep 06 2011