Aristotle 2: The Philosopher

okay so we're going to be continuing our discussion of Aristotle here focusing more on his philosophical views rather than his logic Aristotle is an incredibly important person to become familiar with since he was he has an enormous impact on Western society so often in the Middle Ages he was simply referred to as the philosopher capital T capital P and also sometimes as the master of those who know now this is a level a sign of the level of respect that people had for Aristotle's views during this period of time and most people thought that his views were for the most part absolutely correct they had to be tweaked in were there but there really was a feeling in the Western world and also in the eastern world to some extent that Aristotle had put his finger on the most important components of the natures of reality and the way that logic and rational thought work and the rest of everybody else's job was simply tidying up filling in the details making these things clearer and more elicited and so on and so if you had gone to college at this time you would have learned Aristotle's views not in a philosophy class where there was some debate we could talk about where there Ranna assembly as the truth now it's a very heavy and important thing to say so iris taught Ophir was the dis period that's over a thousand years of timer time mom was the Einstein the Newton of his day he was on what who people just I had absolutely nailed it so whether you think he's right or whether you think he's wrong it's important for us to get some kind of grip on what his actual thought about this stuff was so let's start with the basics talking about philosophy here for Aristotle so Aristotle divides philosophy up into two components there are the theoretical fields and in a theoretical field what you're aiming for is knowledge so physics is a theoretical branch of philosopher Aristotle biology what he calls first philosophy which is metaphysics and epistemology these areas aim for some abstract body of knowledge but these are distinguished from whatever sort of calls practical components of philosophy which don't aim at producing knowledge but aim at producing some kind of action and so for him then ethics is a practical science because the the goal of science the goal of ethics is not merely to know what the right and the good are but to produce the right actions into good persons so for Aristotle to politics would also be a practical science and those would be distinguished from the theoretically oriented branches of philosophy so what we've been calling natural philosophy which is philosophy the natural world as well as metaphysics are theoretical sciences ethics and politics would be practical sciences now we're going to be focusing here on the theoretical area and it didn't look at the ethics course for Arizona's views in the practical areas at least in ethics I don't really talk about his philosophy of politics now the goal for Aristotle in these branches these theoretical branches of science is to start with particular things figure out what those things have as their essential characteristics then to move to using these as premises in a syllogism so Aristotle thinks that the way you categorize things is by the way that they're the same and also they'll have a differential different differentiating quality which is their essential attributes so for instance take human beings human beings are animals just like dogs and cats and monkeys and zebras and so forth but there's something which distinguishes us from all of the other animals and that's being rational so we are the rational animal and rationality is essential to being a human being so an essential property is one that makes it the kind of thing that it is in which that thing can't lack without failing to be the kind of object that you're talking about an essential property is one that the object may or may not have for instance as a human being whether I have hair or not is not essential to being a human being whether I have a finger even or a toe or a leg isn't essential but what is essential to being a human being at least according to Aristotle is being rational so all things are categorized this way there's a a general species of which we belong and in some genus that differentiates us from those species so this is the way he would organize and categorize everything around us now he develops into a nice general method here so you can see that on the left-hand side you start with the general opinions of people who came before you and Aristotle always starts his his investigations with a canvassing of the views of his predecessors people who came before and this has been very useful to us because it's where we get a lot of information for instance about the pre-socratic philosophers they a lot of that information about Parmenides and Zeno etc come from Aristotle's work where he's taking stock of the problems that were left to him so then you engage in dialectic which is you know coming from the Socratic method so dialectic is involved is it's conversation this deep conversation where you're trying to get clear definitions and really get at the essential properties of objects and you distill out from those first principles now first principles are things like that are that distinguish the universal and necessary attributes of the things that you're interested in so for instance all dogs are mammals you knowing that a knowing that that's true is a first principle and that allows you to do whatever so called a demonstration a demonstration is simply a valid syllogism so the section on logic that we just covered is being put the use here that's one way that we come to know about the world so this kind of structure here is different than Aristotle's the excuse me then Plato's divided line we have a part where we're ascending upwards from opinions through dialectic to distilling out the first principles and then a portion what we're moving down from those first premise principles to conclusions about the way the world actually has to be now a demonstration isn't just any old kind of syllogism but it's a syllogism whose premises are necessarily true which premises can't be false and that's how you get knowledge about the world according to Aristotle as you start you employ this method okay so what he's interested in is an explanation and an explanation for Aristotle really takes the form of a deductively valid syllogism and that's because it doesn't merely tell us that something is the case but it has to tell us why it has to be that case so Aristotle's theory of science and philosophy is that we mind necessary and universally true facts about reality and then you're able to explain why reality has to be that way so to really understand it to really know it we must be able to give the reasons why that thing has to be the way that it is and these explanations usually take the form of valid syllogisms which as we've discussed in the previous section are arguments with two premise in a conclusion so just as an example here suppose that you knew that copper conducts electricity now Aristotle wouldn't have known that but we know it so what explains that fact about copper why does copper conduct electricity well copper is a metal and it's an essential component of metals that they conduct electricity so now you can put this in a form of syllogism all metals conduct electricity all copper is a metal so all copper conducts electricity now you've deduced the fact that copper conducts electricity from these other facts namely from the essential attributes of metals as they're being conduits for electricity and from knowing that copper is in fact a metal now you understand according to Aristotle why copper has to behave in the way that it does so the goal of philosophy is to arrive at these kinds of syllogisms where we deduce the nature of reality from things which we already know to be true now first principles of a science are known directly by reason in a way that does that does not need any further proof and again this is exactly like geometry and the the heavy emphasis on the geometrical sciences that we've already seen in the work of every pre-socratic philosopher in the work of Socrates and in a work of Plato so for instance take the theorem of geometry that the shortest distance between two points is a straight line you can't give any evidence for that that's the kind of thing which you have to just think about and then you can see that it must be true how could it possibly be the case that there's a shorter distance than a straight line that's knowable just by thinking about it it's noble immediately and intuitively and doesn't need any further support that thing can then be used to support other things and so it could be used in a demonstration in a valid syllogism now so for instance less geometrically and more logically Aristotle thinks that the law of non-contradiction is something that's immediately known by reason and can't be given any proof for so the law of non-contradiction is the claim that no sentence or no fact can be both true and false at the same time notice Parmenides was talking about this Zeno uses this idea Socrates uses it when he talks about Euthyphro and this theory of Justice with rheticus Plato uses these ideas this is something that have been percolating in Greek thought for some time and Aristotle distills it very precisely gives it a name the law of non-contradiction reality is such that no contradictions are true now you can't give an argument for that claim Aristotle says you don't need any evidence for it it doesn't need any support except itself once you understand the words nothing can be both true and false at the same time then you can think about it and see that it just has to be true and that's of course what all of the logic that we were just discussing in the previous his lectures was based on because if you deny the law of non-contradiction then validity as we defined it simply goes away if some sentence can be true and false at the same time then knowing that the premises are true and the conclusion is false doesn't tell you the argument is invalid because the conclusion might also be true so it's only this law of non-contradiction which tells you you can't have true and false that allows us to build the system of logic which we were exploring all logic is based on this idea so the law of non-contradiction according to aristotle is supposed to be a necessary truth about reality so what that means is that it's impossible for it to be false and notice that it has two interpretations a metaphysical interpretation whereby no object can have contradictory properties and also a logical interpretation whereby no sentence can be have contradictory truth values these are very different obviously related and Aristotle thinks that they are related and that the logical interpretation follows from the view about the nature of reality now once you have this you have a very powerful way of arguing which Aristotle calls a reductio ad absurdum which simply means in Latin reducing something to the absurd so if you wanted to show that something was false or that something was true what you could do is try to show that a contradiction results from it so for instance if you want to show that X is true to assume that X and then try to show that that leads to a contradiction thereby concluding that the original thing which led to the contradiction contradiction cannot be true now this argument form is employed a lot of times well you say that P will assume that P is true P leads to a contradiction so P can't be true that's a very powerful way to argue now of course this is what I'm sleeping under the carpet here something which we should talk about which is that you need another basic printing which Aristotle calls the law of the excluded middle now what the excluded middle says is that every sentence is either true or false and there's no third alternative so every sentence is either true or false and there's no third alternative like not the like non determinant everything has a determinate truth value and this gets Aristotle into some trouble for instance thinking about sentences about the future there's a very famous example where Aristotle is considering the sentence there will be a sea battle tomorrow if you accept this law of excluded middle that like the death sentence either true or false already even before the sea battle has occurred and that leads to some interesting things which we may come back to later but we'll set that aside for right now okay so one thing that we want to do is make sure that we understand Aristotle's attack on Plato so Aristotle did not agree with Plato about the theory of the forms he was very very very clear that he thought that plato was misguided in positing an eternal realm of non-physical eternal and unchanging objects Aristotle thought that all that there was was the physical world around us so let's go ahead and try to understand what Aristotle's point is here so Plato attempted to do what Aristotle was interested in Plato attempted to try to give explanations for why the things must be the way they are so for instance suppose you want to know why is that thing a human being why isn't it a dog well Plato says its thing participates in the form of human being the form is eternal perfect and unchanging it's the essence of what it means to be a human being or in other words it's the perfect human being and it's this relationship of participation in some sense by resembling the perfect human being which explains why I have to be human as in a why I can't be a dog now Aristotle is very unhappy with this notion of participation it's extremely unclear and in fact what I wants to try to show is that it really doesn't explain anything at all so we can look at this picture here this is Plato's picture we have the visible world which is physical finite and constantly changing the world of becoming and then we have for Plato the intelligible world which is non-physical eternal and unchanging the realm of being and every human being in the visible world is related to some form the form of human being in a star relationship which explains why those things are human so Aristotle says well basically what we have here is a principle that for every group of objects there's a form which explains what that group has in common but now if we think about the form of human being itself and ask the question is that thing a human being it seems like Plato's answer has to be yes it's the perfect human being it's the flawless human being it's that way forever unchanging but of course it's our resembling that thing which makes us human but if that's the case then we have a larger group the group of all physical humans and the form and Aristotle wants to know what is that group have in common well it seems like there must be some third form the form which unites all of these things but you can repeat this process as many times as you want and it seems like you lead to an infinite regress so we can put this in words as follows the form is supposed to explain why it is that we call some things by the same name but that name must also apply it to the form itself and that's because it's the thing that all instances of the form have in common so it's sometimes easier to think about colors here so if you think about all the blue things in the world Plato says those things are blue because they resemble the perfect blue what is the perfect blue itself blue oh yeah has the example of blue but if that's the case then you can create a new group all of the physical instances of blue together along with the form of perfect blue now what explains what those things have in common well it's got to be this third form this other form the form of what unites those things but then you can create a group out of that physical objects the form and the form which explains what they have in common and now you need to know what those that group has in common so you can do this for anything which is a form all of the objects and the form they must have something in common and so on and so on and so on so this generates what Aristotle calls an infinite regress which means that you never get to the end it just goes on forever you can make bigger and bigger groups and always ask what those things have in common so since there's no end we never really get an explanation of why humans differ from dogs we are simply told they resemble the form which resembles something else which resembles something else which was something else so this is what has through history become known as Plato excuse me Aristotle's third man argument the third man argument is supposed to show that the theory of forms as developed by Plato doesn't accomplish its goal so Aristotle rejects the theory of forms as developed by Plato he also rejects Adam ISM which we discussed in the lecture on the priests toddles very disturbed by some of the central tenets of atomism so the idea of void is contradictory remember we've already discussed that a little bit because it implies that what does not exist in fact does exist in Aristotle just denies that that's the case he says that's a contradiction that which doesn't exist can't exist so there can't be void he asserts that everything is filled at every point so just as the space between you and and your friend or the competitor is filled with air so to every space is filled with something whether we can see it or not and also Aristotle rejects atomism because if it were true then the world would not be explainable in his sense because we couldn't say why the stuff around us must be the way that it is since according to Adam ISM everything is ultimately the result of chance so you can't say why a dog has to be a dog can't say there's some particular essence that dogs have horse a day is well randomly some atoms came together and they formed those things over there and soon those will disperse and that's the end of that so Aristotle's deeply disturbed by this view what she thinks is at odds with the way the world actually works for Aristotle the world is ordered the world is law governed and it works according to necessary laws which describe the way the world must be at any given time as opposed to the atom is who said oh you know it's all just chance there's things but atoms W together some stuff forums some stuff disintegrates that's just the way that it goes okay so Aristotle has to start over and he's starting over involves him giving an alternative explanation medicine metaphysical system which we're going to look at which is known as the four causes so he agrees that we want knowledge of essences remember that's what Plato was after the forms are essences and in fact even confusingly for us when word form for these essences with a little F instead of a capital F but the forms of Aristotle are not separate from the objects around us so he agrees that there is some property which all and only dogs have and which is responsible for their being a dog it's just that he doesn't think that that form is somehow separate from the object each object for Aristotle is composed of two parts the matter out of which it's constructed and the form which shapes so to speak that matter so a dog is composed of a particular dog my dog your dog is composed of some material formed or informed by the form of a dog so the form is somehow what makes that material be a dog but the form is in there it Aristotle argues that these two things the form in the matter are separate able in thoughts but not in reality so this is where Plato went wrong according to Aristotle he confused what we can do with the mind with the way reality has to be so we can look at some object and separate out the property of being read and the property of being a ball so we have a red ball we can say ah there's the one thing which is the redness of the Valen thing being the ball but it's a mistake to think that the redness can exist independently of the ball according to Aristotle the property of being red is located inside the object the form of red is in the object not outside of the object but in which it stands in some relation so Aristotle thinks that each red object has the very same form of redness inside of it that's what they all have in common the same now this leads to some difficulties because he is forced to say it's the very same thing which is simultaneously located all over the place now that sounds a bit strange to people but Aristotle's fine with it so again for each red object we can separate the redness the form of red from the material but it's a mistake to think that those things can really exist apart they can only exist together so it was known as eros high-level morphism and that's just a fan word for saying that there are two things here the form and the material now even though this things can't exist you have to have every material has some form and every form has to be in some material but even so the form is separate from the material it's real it's a real thing it's just in the material it exists as part of the object now this is part of is in response to Parmenides how change is possible it's going to argue that change consists in a material coming to have a form that it did not have before and this is going to solve a lot of problems but we're going to wait a bit to talk about that so remember from before that to really know something Aristotle thinks that you have to be able to explain why the thing has to be the way that it is and cannot be some other way that is what we need to do is to be able to give the reasons why the change happened or why the thing is that way now the word that aerosol actually uses idea is translated as cause that's a little bit misleading for modern people because really what he means is the reasons that explain why the thing happened the way that it did or is the way that it is so really he's interested in the reasons so let's consider some sculpture so here you can see a picture of a sculpture of Socrates there is a snub nose and his brows as we discussed earlier not an attractive person so what are the reasons why this particular sculpture is the way that it is well sculpture is the result of a process and Aristotle thinks that there are four causes each of which partially explains why it is and all together fully explain the way that it is so for instance part of the answer is that this is made from a certain material in this case let's say marble if it was made for gold it would have different properties if it was made from concrete it would have different properties if it was made from mashed potatoes to shaving cream it would have even different properties so part of the answer is the material that is made out of right they can already tell material is important now the other part is the shape that it has the statue is the way that it is because it's shaped like this in a Socrates shape if it were shaped differently in an Aristotle shape it would be a sculpture someone else so the shape in this case that's the form partially explains why the statue is the way that it is but of course part of the answer also involves a person who sculpted it in order to achieve the end product the sculpture so actually there are four distinct reasons why the thing is the way that it is these causes Aristotle calls the material formal the efficient in the final causes now a easy way to try to figure out which is which is by thinking about them in a particular way so if you want to identify the material you have to look for the thing which stays the same during the process so in every instance of change there is some object which is the same as it undergoes the change and that's very clear to see in this case when the sculpture is making wearer is making this sculpture the marble stays the same through the process it's not as though by sculpting it you change it into spaghetti or change it in the shaving cream it's still marble at the end so there's something that's undergoing this process that's the marble whatever it is that's undergoing the process is the material costs now the formal cause is the thing which actually changes it's the difference so the ring which is the same and then the thing which is different so in this case the marble is the same but its shape is different it no longer has the same shape that it did before so now we know that the formal cause in this case is the shape of the statue now the efficient cause is just the thing which initiates the process nothing just starts by itself Aristotle things there's always got to be some thing which initiates the change that thing which initiates the change is the efficient cause in this case the efficient cause is the sculptor the artist that's the thing which is making the change happen so to speak and then finally no pun intended we have the final cause Aristotle says the final cause is that for the sake of which the change is done so Aristotle is very teleologically oriented where Telos from the Greek word means goal or purpose and so he thinks that everything that happens happens for some purpose nothing that happens is completely random and as aristotle is fond to say what we call chance is just ignorance of the actual causes so if we really knew what was going on we when we would see that there is no chance or randomness in the universe Aristotle thinks everything happens for a reason now here the final cause is the image or picture a finished product that the sculptor has in his mind so for instance a famous sculptor once said that when they looked at a block of marble they could see the statue trapped inside of it and all they were doing was trying to free it and that's a sort of way of talking about this idea final cause the sculptor has an image of what the finished product is supposed to look like and in their action by chiseling by hammering at the piece of marble they are trans that image into the material of the marble and this metaphor here is central to Aristotle's way of thinking in every case of change what you have is some material which is receiving some form which is being transmitted or put there by some agent in order to achieve the purpose of having the final product now that sounds a bit confusing but we'll look at several examples and try to get and a hang of it so now just to sum up though to give an example to excuse me to give an explanation of change Aristotle things you need to specify all of these causes so we've just done that for the sculpture why does the sculpture exist why is it the way that it is well because it was made out of a certain stuff because it has a certain shape because an artist did it in order to get a statue with that shape now it's important though to realize that the sculpture example can be a bit misleading so when we think about the sculpture example we can be led to think that material is simply stuff like marble wood gold etc we can be misled to think that form Assembly shape and that efficient causes are always persons but this is extremely misleading because Aristotle thinks that these categories apply to every process of change including such things that objects following the planets moving people walking etc any process or change needs to be explained in terms of these four causes so for instance and what the causes are depends on what you're trying to explain so notice that what we were earlier trying to explain was why the statute is the way that it is suppose that we were trying to explain why the statue was red as opposed to simply why it exists well in we're going to get a different set of four causes so the material in this case is the statue itself the statue is the thing which is the same it's not as though painting a statue red changes a statue from it to a non statue so we don't talk about marble when we're trying to explain why the statue is red we explain that by saying that the statue under process so the statue is itself the material in general Aristotle counts a substance as any kind of thing which we can attribute properties to statues are substances persons or substances cows or substances couches etc now the shape excuse me now the formal cause of this is nothing to do a shape so what's different have before and after the painting well the difference is the color of the statue so here what we have is the form of red being transmitted into the material the statue now of course there's got to be an efficient cause and we're assuming that someone is doing the painting so whoever is doing the painting is the efficient cause but of course statues can become red for other reasons as well so suppose that the statue is made of marble and it's sitting on water dripping on it it may become discolored over time due to the water interacting with the statute so the statute there would be acquiring a new form the form of this color the formal cause would be whatever color it's acquiring but the efficient cause in this case would not be an age in a person it would be this process of dripping now the final cause in this case is again related to the purpose which the process happens for so if it's a person painting then the purpose is what's ever envisioned as the goal by the person to paint the statue red and in general there's a very close connection between the formal cause and the final cause the formal cause tells you what property the thing acquires the final cause tells you why it occurs why it acquires that property and there's a tight Kingdom between them so if you know what the formal cause is then it's very easy to identify what the final cause is okay so I understand that this is all very new so let's go through a couple of more examples let's suppose that we have a pan and we're heating the pan up and we want to explain how the pan goes from cold to hot we have a pan it's on a fire so what's the material cause here well we want to know what thing is the same in what would be the pan itself it's this frying pan which is undergoing the change so in this case the pan is the substance it is the material which is acquiring the new form it would be wrong to say that the material is iron or steel or whatever the pan is made out of that would explain a different fact that would explain why the pan is the way that it is it wouldn't explain why this pan is heating up the pan itself as a pan is the thing which is undergoing the change okay so now the formal cause is that thing which is different so we have a cold and then after the process we have a hot pan what's the difference well the heat is actually the difference in Aristotle would say that the form of heat has been transmitted into the material of the pan now of course there's always got to be something which does this transmitting the efficient cause and in this case it would have to be something which has the form of heat already the form of heat just doesn't pop into the pan from nothing there's got to be something hot which transmits the form of heat into the pan now of course poor Aristotle doesn't know about chemistry and so he doesn't know about chemical reactions whereby heat is seemingly generated without something hot being around already and so this might be a kind of challenge to his view so this might be a kind of challenge to his view but we'll leave that aside for now so for now we'll just say there's got to be something which possesses the form already and is able to transmit it into the material now of course the final cause is related to the formal cause as previously discussed and here the final cause is to have the form of heat in the material right half the hot pan now this is an important point that we need to stop and dwell on for a second Aristotle introduces a distinct between something actually being a certain way and it's potentially being a certain way so when the pan is actually cold Aristotle will say that it is potentially hot now what that means is that the pan is able to receive the form of heat so potentiality for Aristotle is determined by the kinds of forms which a material is able to accept so for instance the pants is not potentially an eagle because the the pan cannot accept the form of an eagle and then be an eagle the pan is an inanimate object and cannot be turned into an eagle by transmitting a form of Eagle into it so there are many things the pan is not the pan is not potentially walking new pan can walk the pan is not potentially speaking English to pay is not potentially a mEagle it's not potentially the queen of Elizabeth the third is potentially not the moon and etc etc but yet there is a vast range of potentials that the pan has all determined by the material itself the kind of thing that it is and which forms that material is receptive to so the pan is potentially hot it's cold it's warm it's black it's blue it's orange it has all of these various potentials which are again determined by the kind of material that it is now in order to become actually hot as previous previously mentioned the material needs to come into contact with something that is itself already actually hot so in Aristotle's terminology the thing must possess the form of heat already and what that thing does is transmit or transfer the form to the material so notice that in our previous in this example of heating up the pan it's the fire which is the officious the fire is the thing which is transmitting the form of heat into the pan it's not a person doing it you aren't transmitting the form of heat into the pan it's whatever hot thing is around which has the form of heat already is putting that into the pan so already we have an example where the efficient cause is not a person the efficient cause is something in the natural world fire so in a sense then we can conclude Aristotle says yeah you know properties do exist in the same object except as actuals and potentials when the pan is actually cold it's potentially hot when the pan is potentially hot it's actually cold and vice versa when it's actually hot is potentially cold when it's actually blue is potentially red and etc and etc and etc now this solves the puzzle that we were discussing from before of how it is that you could explain how something changes and changes a nothing is not the case that the heat came from nowhere it came from the fire which had heat and is transmitting it into the pan and that he was already there in a sense in the pan and the form of a potential which means that the pan could accept the form of heat so you don't get something from nothing it's not the case that opposites really exist at the same place at the same time except as one is an actual and one as a potential okay so let's do another one suppose that we have syndicates you drop it and it moves in a straight line down to the ground well what explains this again Aristotle thinks the four causes explain it so we want to identify the thing which is remaining the same through the course of this change and that will give us the material so we have this rock we let go of the rock it moves in a straight line down to the ground when it gets to the ground is still a rock so the change is that it was moving check change location but the thing is still the same so in this case the material is the rock the material is the rock and in fact Aristotle defines earth as objects which move in a straight line down to the ground all things which move in a straight line down to the ground when they're dropped are composed of earth so this thing fall a rock now it's important that we stop here for a second and remind ourselves that Aristotle rejects atomism and he endorses the older view that reality is composed of the five elements which have these sets of complementary properties so earth is cold and dry water is cold and wet air is hot and wet and fire is hot and dry and then there's ether which is a divine substance which nothing on earth is made out of but all the heavenly planets are made out of very different view than what the atom is held or what we ourselves hold today so now it's earth as something which is cold and dry has adds its essential property moving down towards the center and all of these are in there so to speak in that they occupy a characteristic place in reality so you have earth at the bottom you have water on top of that air on top of that fire on top of that and there's common-sense reasons for thinking that this is true so for instance earth it should be at the bottom because earth will move through other things it moves through air and moves through it'll move through fire but those things cannot move through earth so water should be on top of that for the very same reasons and air on top of that and fire of course at the top because the natural movement of fire is upwards so for Aristotle each kind of thing in the world has a natural kind of movement something which it possesses by its nature earth moves down fire moves up and this of course you can just observe things are made of Earth will fall downwards when dropped but fire is moving upwards when it burns so then we can say that the material here is earth and the formal cause is something which Eversole calls the heavy and the heavy is simply the form of moving towards the center of the universe which is what he thought was going on here the efficient cause is that so this this form this rock possesses within sight itself the ability to move itself in a straight the four person center of the universe fire possesses within itself the ability to move upwards in a straight line away from the center of the universe so these things according to Aristotle are not inner objects they are things which possess abilities they are doing something and of course the final cause then is to be at the center of universe that's where the process stops that's the final goal of the rock is to be down there now of course it sounds weird to us modern people to say that the rock has a purpose when it's falling and that the purpose of that falling is to be at the center of the universe but when Aristotle looks at the rock he sees something purposeful he sees something acting in a kind of manner in order to achieve a goal the goal of being at the center of the universe very different from the way that we think about rocks in their movement okay so it is the nature of earth to move downward now water moves downward also though not as much and I've already said why rocks fall through water but nothing falls through a rock air moves up and you can think about carbonation as it moves up through the water little bubbles moving up and carbonation is a natural phenomenon and would not have been unknown to the Greeks and of course fire moves upwards most of all now Aristotle actually thought that everything else is composed of these elements so for instance table it would must be composed of earth and air it's got to be composed of earth because when you drop it it moves in a straight line down to the ground but it's also got to have some component of air in it because when you put it on water it doesn't sink it floats so that must be the upward movement of the air so I ever thought all things out well there must be a ratio in there of more earth - less air such that it's not enough air for it to flow upwards but it is enough erred and sinking in the water and this is he goes through and actually tries to figure out the ratios of various things for parts earth one part air well that will give you would three parts earth two parts air well that might give you blood something like that and all of the various things around us are composed of these basic elements again a very alien view to our modern people okay so I have to stress this because it's so weird for us the pen is not being moved by anything external to it so Aristotle thinks excuse me the rock is not being moved by anything external to it Aristotle things that the pen moves itself what it means to say that earth is heavy is that it has this power it has this ability what it means to say that something is fire is to say that it has the power to move itself upwards so this is what Aristotle calls a natural process because the efficient cause is something which is internal to the rock process is one where the efficient cause is external to the source of change so the sculptor example that's an artificial process you kicking a rock that's an artificial process but a rock falling or an apple falling from a tree and hitting the ground that's a natural process because the principle of movement is somehow contained within the actual object itself alright so just to sum up this stuff Aristotle also gives several he describes the way things fall and move around here and they're all geometrically based so one of his claims is that heavier bodies fall faster than lighter bodies so for instance he thinks that if you dropped a hundred pound weight and if you dropped a 10-pound weight the 100 pound weight would hit the ground first that's a common-sense kind of thing well you see it's heavier so it's going to be falling faster and of course it's sort of a verified by our common sense everyday experience if you drop a bowling a better the bowling ball hits the ground first draw the piece of paper and a pen pen hits the ground first common-sense observation so again Aristotle thinks that the speed of an object is in direct proportion to the force applied to it so he thinks that the natural the natural position of objects is at rest and that's because when you look around objects are at rest unless you force them to move nothing no inanimate object moves itself place of an object and even when you drop something and only move so far and then stops so objects don't move unless a force is applied to them and those objects stop moving when the force is removed from them now the last thing we'll note here is that the speed of an object is inversely proportional to the density of the medium it falls through so for instance the denser the medium the slower the object is if you drop a rock into water the density of the water will slow the rock down but of course you to molasses the density of the molasses really slows that rock down so it's inversely proportional the more dense the slower it goes then the finally summing up Aristotle's physics here the motion of the planets why do they move in circles is due to them being composed of ether ether Aristotle thinks is a heavenly divine substance whose essential attribute is movement in circles present tense is made of this weird stuff is not made of earth if the moon were made of earth they would move in a straight line down towards the center of the earth it wouldn't fall on us and crush us so the fact that it doesn't fall on us Aristotle thinks shows that it's made of ether a special kind of substance which is found nowhere on earth and which nothing on earth is made of because nothing on earth has as its natural movement circular motion so this is a very alien worldview one we find so far removed from what we think as to really wonder who could Aristotle have taken it seriously the answer is yes people thought these views were true all the way up until the time of Galileo Descartes and Newton and they started people started breaking with this Aristotelian tradition tradition and that's what we're going to be exploring in the next set of lectures

Channel: Richard Brown

Views: 23,466

Rating: 4.8499999 out of 5

Keywords: Aristotle The Philosopher, 4 causes

Id: -sxRsHIC1f4

Length: 50min 24sec (3024 seconds)

Published: Mon Oct 10 2011