1 Historical Introduction (General Philosophy 2018 - Peter Millican)

welcome to the first of eight lectures on general philosophy and in these first two lectures i'm going to be giving a historical background to a lot of the discussion that comes later in this first lecture some of the uh the figures we'll be considering well there's monty python's god at the far left then plato and aristotle galileo and renee descartes let's start by asking what general philosophy is well it's contrasted with ethics or moral philosophy it is focusing on theoretical questions and particularly some central questions of epistemology that's the question of what can we know and metaphysics what is the fundamental nature of things part of the point of this course is to illustrate how philosophy is done it will show you types of argument methods of inquiry that you can use more generally and the course as you'll have seen from the reading list has a historical focus the six topics are all introduced through the writings of great philosophers of the 17th and 18th centuries namely rene descartes john locke and david hume now it's worth spending a little time on the role of these lectures much of your learning in oxford will be structured around small tutorials typically in pairs so it'll be two of you and a tutor and this provides a wonderful opportunity for developing your philosophical skills normally you'll be asked to write an essay for a tutorial like that and the tutorial will be focused on critical discussion of your ideas that's something that you can only acquire in that way and it's a very valuable learning experience but tutorials are not expected to cover everything that you learn lectures are provided to give the context wider coverage to go through topics that you won't have time to do in all your tutorials showing how different topics link together within a broader framework so the kinds of skills that you acquire in your tutorials where you're being challenged on your own ideas where you're learning to think carefully and critically about those ideas those skills you can apply much more widely if you've acquired the general knowledge of the topic area through lectures now the topics that we consider in general philosophy are especially fundamental they draw on and they contribute to world views that go back to in antiquity and importantly they remain of tremendous interest in our lives today so i'm going to say a little bit about the role of history within this course one pragmatic point i'll note is that the examiners for general philosophy would like to see understanding of the primary texts they consider it a virtue that you should be able to show significant acquaintance with historical material it's an interesting question why should that be and i'll come to that in a moment specifically we've got six topics descartes is listed on the reading list for three of them hume is listed for four of them john locke is listed for personal identity and the particular works here are descartes meditations the an edition is shown at the top there on the right david hume's inquiry concerning human understanding and the chapter on personal identity from locke's essay the six topics all of them have a pretty wide linkage historically knowledge and skepticism will be coming across descartes skeptical arguments and his evil genius the veil of perception is associated with john locke and with actually a fair amount of early modern philosophy the idea that our perceptions don't give us immediate access to what's really there so how do we know what's there and we'll be seeing hume uh playing a large role with regard to skepticism he's an advocate of what he calls mitigated skepticism as we'll see in about the fourth lecture hume's argument concerning induction will play a large role in the third lecture god and evil we will come to towards the end of the lectures descartes famously argued for god's existence hume equally famously argues against it appealing particularly to the problem of evil free will is a topic that continues to be discussed often in much the same terms as it was in the early modern period thomas hobbes and david hume advocated compatibilism which is still a very popular view of free will and took a naturalistic view of man as part of nature which again has resonated down the centuries descartes is particularly associated with claims about mind and body and we'll be talking a bit in the next lecture and later on in the lecture series about the relation between mind and body and lock features in respect of personal identity he started out a discussion which is again continued down to the present day before going on i want to mention uh some previous lectures that i did these were recorded in 2009-10 you can see they're freely available and they're slightly different from the current lectures in in various ways there's obviously a fair bit of overlap but they include some topics that are not now in the syllabus perception and primary and secondary qualities they don't include material on god and evil which wasn't then in the syllabus and they give a little bit more detail to some of the historical background so the current lectures aim to complement those these lectures contain more thematic material drawing more connections between subjects and more links also with other oxford disciplines that you may be studying alongside philosophy okay let's go back now to that question of why we should bother with philosophy's history why does history play such a large role in our introduction to general philosophy if you want more detailed discussions uh in the tur centenary of hume's birth he was born in 1711 and in 2011 there were lots and lots of activities going on to celebrate his 300 years and i ended up giving quite a few talks that year as you can imagine and amongst those i was discussing precisely this issue why are philosophers so interested in the history of philosophy and there's a couple of papers there on the web you're very welcome to go and look at them you'll see on there on the davidhume.org website and incidentally all of david hume's philosophical works can be obtained free from davidhume.org as well as lots of papers that i've written so here briefly are some responses well first of all the agenda got set by these people many of the problems that we're looking at are problems that arose for the first time in a discernibly modern guys in the 17th and 18th centuries that's not a coincidence right the reason they arose then was because that was when the scientific revolution was happening and the modern world view came about over that time so there's a very very big difference between the world view that you get in the 1500 say and the 17 and 1800s and a lot of problems that beset us now arose then and not surprisingly those problems got raised for the first time and in a very vivid form by some of the best writers and thinkers of that period now as a result the labels that we attach to various prominent positions within those debates naturally carry the names of the philosophers involved for example cartesian dualism is the form of dualism advocated by descartes it's named after him human compatibilism so if you're discussing free will an important position is compatibilism and there are various varieties of that one of them is associated with thomas hobbs a slightly different version with david hume many modern philosophers may have exactly similar views in various ways but we don't name them after them because hobbs and hume got there first perhaps even more importantly these were very great minds the the people whose works you will be reading from the 17th and 18th centuries were absolute you know undisputed geniuses moreover they were addressing these problems for a general public they weren't writing for academic philosophers and as a result their work is accessible much more so than many modern discussions that you'd have another point about historical perspective philosophical ideas have very broad very deep interconnections i've said already that even people who are specializing in one particular area of philosophy invariably find that their study links to lots of other areas now um one problem with studying philosophy as it were in disciplinary silos like in when you come to do your final honours papers for example is that you don't get time to see all of these links inevitably if you're focusing in on one particular area say moral philosophy you're not going to be discussing at the same time links that there may be with say philosophy of religion or epistemology or metaphysics but but there are very large links there and often those links are easiest to see in the writings of older philosophers because people like descartes and hume were trying to develop comprehensive philosophical views taking account of lots and lots of different areas they weren't as it were academic philosophers trying to publish in some specialized journal so by looking at the way that their ideas interlock in history you get an appreciation of these wider connections now another point a very important point is that a lot of the same themes recur throughout history sometimes these aren't so obvious but i've come across cases recently where discussion say in the philosophy of mind you know issues about artificial intelligence can machines think some of the issues that are raised there some of the arguments that are given there are ever so similar to arguments that were given in the 17th century and important responses were given in the 17th and 18th centuries and often now people will discuss these things in complete ignorance of the prior discussion um finally we have to be aware of our own historical blinkers we all come to our studies with particular preconceptions and this is true of academics as you know well as students and ordinary people in the street as it were it's really healthy to be looking at philosophical views from very alien times so for example you may well be an atheist and you may read descartes and think it's strange that he relies so much on god but actually you can learn a lot from seeing how he does and what how god functions in his system you shouldn't be saying oh well he's got different beliefs from me therefore i'm going to take no account of it because often looking at a worldview that's profoundly different from our own can highlight things about our view now in general philosophy we're going to be focusing particularly on ways of understanding the world and our place in it so this is if you like theoretical philosophy so this course could equally have been called introduction to theoretical philosophy and that's contrasted with practical philosophy so practical philosophy in particular would be ethics and political theory questions about how we should behave now obviously i'm going to be focusing on therefore the history of epistemology and metaphysics there is an equally important story to be told on the practical side and i'm not going to be saying very much of that um but you will see from today's lecture and next week's lecture that philosophical thinking has had an absolutely profound effect on the world i think it's entirely plausible that philosophy more than any other discipline brought about the modern world in contra distinction with the medieval and ancient world and although i'm as i say not going to be talking about the practical aspect of that that is also obviously extremely important the fact that now we don't believe in the divine right of kings now we believe that government legitimate government comes from a democratic mandate etc so from time to time in these lectures i'm going to be saying things that link with particular other disciplines that are studied together with philosophy in oxford as you know we have no single honours philosophy degree amongst the combined degrees we have is philosophy and theology and these are intimately connected if we go back into history most philosophical thought across most of history has been intimately connected with religion religion seems to be pretty much universal in at least ancient human societies religion and philosophy have many positive but also some negative links one issue here is that religions typically emphasize orthodoxy you've got to believe the right thing if you're going to be in the club if you're going to achieve salvation if you're going to be in favor with religious leaders and so on and that means that in periods when religion or a particular view of religion has been dominant that's often been rather bad for philosophical variety and this happened hugely in when the roman empire became christian uh thanks to constantine a lot of ancient philosophical schools were basically stamped out so plato's academy for example have been going for 800 years and it just stopped there we'll be seeing that in the period that we're looking at the early modern period some of these ancient influences actually came back and so i'm going to now take a detour through looking at some of the uh the christian background and then we'll see how uh problems emerged in the early modern period which essentially brought about the birth of modern philosophy okay well most of you are probably familiar with the the genesis story uh in the beginning god created the heaven and the earth and he did it in this order you might find it a little bit strange that the earth got created before the sun and the birds got created before land animals but there you are what i'd want to draw attention to is that when man was created let us make humankind in our image according to our likeness says god let them have dominion over all the animals so god created humankind in his image in the image of god he created them male and female he created them okay genesis chapter 2 you actually get a different order of creation and here it is very clear that humans are being given dominion over the earth eve is being created out of adam's rib as a helper for him you can see very much we are in the image of god the world is being made for us what sort of philosophical view does that suggest well it suggests that the world is going to be something with which we are intimately connected of which we can learn using our god-given faculties in a pretty direct way it also suggests that the world is going to be infused with teleology with purpose the world has been created by a god who's put us there in his image for a reason to do uh his works and you can see in ancient philosophy links with these views and in particular the philosophies of plato and aristotle in various ways fitted quite nicely with this general view of the world and it's not surprising therefore that these were the philosophers who were most popular with early christians plato neoplatonism had huge impact on the development of christianity in the medieval period aristotle became taken on board particularly through the influence of thomas aquinas now what i want to suggest is this is a very natural way of thinking about the world and there are psychological experiments that back up that we very naturally think about things teleologically in terms of purposes so suppose you take a young child and you say why do you think mountains exist is it to give animals a place to climb or is it because volcanoes cooled into lumps and young children overwhelmingly prefer the teleological answer they'll say mountains are there to give animals a place to climb why is the sun in the sky to keep us warm what are trees for to provide shade what is rain for to give us water for drinking always the teleological answer now interesting recent experiments with patients with alzheimer's have shown that they do the same so it seems that naturally we are inclined to judge things in terms of purposes we learn through our education particularly through science education that that's not actually the best explanation of lots of things in the world but then if unfortunately we suffer from alzheimer's disease and we lose our memories we lose what science scientific education has given us we go back to thinking teleologically so as i say it's not surprising that the most influential early philosophies tended to be very teleological in form um and just a couple of examples uh which match with this general idea plato his famous theory of forms uh this links with the idea that the world has been created for us that if we use our reason we can be in tune for it for tune with it we can discern how things really are if we want to understand the essential nature of things we don't do it primarily by empirical observation we do it by reason aristotle too he's got a theory of perception where when we see things the form of what we see the perceptible form of it somehow imprints itself on our organs so we see directly what's there because our sense organs become similar to what we are perceiving and you'll see that this is a huge contrast with what we get in the early modern period another point and this brings us towards accounts of physics is to do with uh how physical things behave so suppose i take a stone imagine that's a stone and i let go of it it falls why does it fall well uh prior to 1600 the standard account was this uh that there are four elements in the universe below the moon earth water air and fire and they all have their natural place in the universe earth at the center water around that air around that fire around that and so if you take something that's primarily made of earth like a stone that will naturally strive to reach its place in the universe the center of the earth and that's why when you let it go it falls it is striving to reach its natural place so the point i'm making here is that not only is the world designed by a purposive creator for us but also physical things in the world act according to something like purposes strivings they are trying to achieve particular final ends so aristotelian science we've got these four terrestrial elements as i've said they naturally move to reach their uh place heavier things that contain more earth are going to fall faster towards their natural place in proportion to their weight nature abhors a vacuum we'll come to that a little bit later there are some things of course that don't fall towards the earth their heavenly bodies if you look up at the moon and the stars and the sun and the planets they don't fall to earth they must therefore be made of something different and aristotle called this ether this fifth element and the reason why they move in circles why do they have anybody to move in circles because that's the closest they can get to the perfection of an eternal creator so again we've got a purposive account of why things act as they do and so here is uh is one image of aristotle's universe you can see you've got water and earth air and fire then the sphere of the moon and everything beyond the sphere of the moon is made of ether you've got the planets moving on sort of crystalline spheres and the fixed stars around the outside now this sort of general view of the world lasted a long time and i think one vivid way of making this clear is to look at the mapamundi from hereford cathedral so this map was dated around 1300 and it's based on the writings of a pupil of saint augustine of hippo and uh those writings go come from about 400. so we've got a work being produced in 1300 based on all on an authority 900 years earlier and you can see that the map puts jerusalem at the center i've marked rome and hereford and noah's ark and eden and babylon that's the world as it looks in 1300 and it hasn't changed much for 900 years now an awful lot changed in the period between the medieval world and the period we're going to be looking at mainly the 17th and 18th centuries all sorts of things uh started creating cracks in this edifice an edifice which was last largely based on the bible and aristotle population grew there was lots of trade there was discovery of the new world so the trips to america obviously columbus in 1492 but lots of others there was lots of economic disruption in the new world lots of silver was discovered lots of gold actually was brought back from various parts of africa and this caused a lot of economic disruption the realization that ancient maps were wrong i mean imagine if you've been brought up to think that that gives a correct account of the geography of the world and then somebody sails off and discovers a completely new land and suppose they discover that people there have quite different religions inevitably that is going to give you pause about your own if you've been brought up thinking that a certain set of beliefs is pretty much incontestably correct and then you find that there's another group of people somewhere else who've been brought up with quite different beliefs it's very natural to ask yourself how confident can i be that the beliefs that i was given as a child are in fact correct there were a lot of technological changes i mean gunpowder came to the west and had a huge impact with regard to the centralization of power it also had a major impact uh in bringing about for example the fall of constantinople so a lot of political impacts work came about because of technological developments and finally here some heretical classical texts that i mentioned were suppressed under the christianization of the roman empire were rediscovered and those had a profound effect in philosophy then along came the reformation so in 1517 luther famously rebelled against the church of rome from the point of view of the university of oxford actually this was slightly unfortunate one of the things that luther really didn't like was the sale of indulgences the fact that the roman catholic church had a doctrine of purgatory that is if you die and you've been sinful but god doesn't want to contem you to eternal hell hellfire then you go to a rather nasty place called purgatory and how long you spend in purgatory depends on how good or bad you've been but crucially crucially you can buy yourself less time in purgatory by donating to the church or of course to universities so this was a very useful doctrine from the point of view of the development funds of the university of oxford but luther thought this was a bad thing a lot of europe especially northern europe became protestant of course luther's wasn't the only variety of uh protestantism uh jean calvin for example was extremely influential and a lot of others but in general a lot of northern europe became protestant and this provoked a counter-reformation from roman catholics for example the inquisition basically there were a lot of very heated uh doctrinal disputes and this gave rise to armed conflict so there were a lot of wars around europe arising from religious differences and these were differences between different groups of christians and we see this nowadays i mean particularly in the muslim world where you say see sunnis and shias apparently you know killing each other with abandoned simply because they have a different variety of islam well in the 17th century there was lots of that amongst christians the 30 years war raged mainly across germany was um particularly horrible uh that went on from 1618 to 1648. we in england saw the civil war and these all fundamentally arose from differences in religious doctrine in 1648 the peace of west failure came about not through any real decision of the war and certainly not any agreement on doctrine but basically uh it was described as a piece of exhaustion the war had so decimated so much uh of the land that it was decided that the best thing to do was for the the various parts of germany to be divided into appropriate princeton's or whatever and if your prince was a catholic then you had to be a catholic if your prince was a protestant you had to be a protestant that brought an end to the war not very satisfactory from a philosophical point of view but very satisfactory from a practical point of view okay so in those last few slides i've explained why over this period from about 1500 for the next 150 years there was a huge amount of tumult across europe a lot of questioning of established orthodoxies and you can imagine that if you've got get lots of debate between different religious groups even if there are all sorts of things that they agree on that's naturally going to raise all sorts of epistemological worries that is worries about what we can know i mean suppose for example that i'm a catholic uh and i believe in the eucharist i believe that in the eucharist service the bread and wine become literally the body and blood of christ and i am faced with protestants who argue against that and i am debating with them not only might that make me doubt whether i've been told the truth about the eucharist or whether i can be confident in what the really religious leaders have told me about that it might naturally shake my confidence about other things too i mean if different people have different beliefs but apparently on a similar basis namely that they've been told it by their parents and by the religious authorities but those beliefs all conflict then it's clear that that isn't a universally reliable source of authority but a particular cause for the scientific revolution was quite different and that was nothing to do with politics it was to do with astronomy now astronomical motions have been of interest to mankind for thousands of years uh partly of course the calendar ways of identifying times of year by when the stars come round but also astrology now from this point of view the planets are particularly interesting the stars just rotate around the world in a in a very uh regular form but amongst these stars there are these bright objects we call planets that move relative to the other stars and they don't just move in straightforward circles around the earth sometimes they exhibit retrograde motion so although mars say may appear to be moving in a steady direction night after night there come times when mars seems to move backwards in the sky not in the direction that you would expect now nowadays we we can explain that quite easily it's because the earth is as it were overtaking mars on the inside uh on its orbit because mars is outside the earth and therefore as that overtaking is taking place mars moves to seems to move backwards relative to the earth and the earth seems to move backwards relative to mars so if you were standing on mars you'd see the earth changing direction too another interesting point is that venus never appears in the sky more than about 45 degrees i think the maximum is 47 away from the sun so the venus is known as the morning or the evening star because we only ever see it in the morning or the evening never dead of night it's never opposite the sun in the sky now aristotle had taught that the planets move in circles so how does that make sense how can we get an account which explains these retrograde motions and these facts about the motion of venus well essentially they brought in epicycles now here's an example with venus imagine that venus is traveling around the earth on the solid circle but it it's moving around a point on that solid circle on its own smaller circle so the point of rotation of venus's circle is itself rotating around the earth so we we have an epicycle that is a circle within a circle and you'll notice that with this model venus will never be too far away from the sun in the sky so by fixing the appropriate geometry you can get something close to the truth that we observe through our telescopes or indeed with our eyes in the case of mars and the outer planets by the way what you have is a large circle around the earth and then another circle circling around that so that mars is going around the earth but sometimes moving backwards interestingly the epicycles for the outer planets tend to have a duration of 365 days interesting coincidence now galileo in 1609 built a telescope the telescope had been invented the previous year in holland he developed a more accurate telescope and he had the bright idea of turning it up to the sky and what he saw completely decimated the previous astronomical orthodoxy i've listed various things that galileo saw uh he saw that the moon did not seem to be the perfect body that had previously been thought this uh ethereal perfection no it seemed to have mountains and valleys it looked like it was a rocky body like the earth he saw moons orbiting around jupiter loads and loads of stars apparently giving the impression that they weren't we didn't just have a fixed range of stars around uh some celestial globe there were more and more as far as you could see and he saw phases of venus now i just want to explain that suppose we have a model like this suppose that venus is indeed orbiting around an epicycle itself going round a circuit between the earth and the sun what is the largest amount of venus that we will ever see well we will see the part of venus only that is illuminated by the sun and i've put venus there on the on the diagram about as far as it can be in terms of our seeing it you'll see if we look from the earth towards venus what we will see is a crescent so i've shown the kind of present you might expect to see there because the only bit we're seeing is the part that's illuminated by the sun and which simultaneously is in our line of sight importantly if this model is true we will never see anything like a full venus we will only ever see a crescent now what galileo saw you can't tell with the naked eye venus is so bright you just see this point of light but what galileo saw is that although venus is often a crescent uh it isn't always sometimes we do see pretty much a full venus never completely full of course because for that it would have to be the other side of the sun and we would not be able to see it because the sun's too bright but we do see venus with most of it illuminated by the sun which implies that venus is on the other side of the sun so basically the aristotelian model simply can't work now that's actually quite a profound discovery it not only implies that the earth is not the center of the universe because we are orbiting around the sun but it also implies that aristotle's physics must be incorrect because aristotle has said that the reason stones fall is that they're trying to reach their natural place in the center of the universe if the earth is no longer the center of the universe then that account is out of the window we've got to have a new physics and once you start looking in detail at the aristotelian picture what galileo realized was that there were lots of other things that galileo that aristotle could not explain like the flight of a cannonball so ancient accounts had cannonballs firing up under the uh the force of the cannon more or less straight and then when the force of the cannon gave out they would fall vertically so cannonballs supposedly flew like that uh whereas galileo realized that actually cannonballs fly more or less in a parabola a sledge sliding on flat ice imagine that you're on a flat a pond iced over and you push a sledge on the aristotelian account it's rather odd that the sledge keeps going after you let go of it because the natural motion of the sledge is downwards not along and once the force of the push has gone how does it keep going well some theorists reckoned it was to do with vortices in the air keeping it going but essentially the physics doesn't work and as we saw aristotle claimed that heavier bodies uh fall faster in proportion to their weight galileo showed that that was incorrect and supposedly he did so by dropping a cannonball a large cannonball and a very small ball from the top of the leaning tower of pisa and they fell at pretty much the same speed i mean it that's probably apocryphal it's pr he probably didn't actually conduct that experiment but a very similar experiment was conducted on the moon by apollo astronaut david scott and sure enough a feather and a hammer fell at the same speed so let's contrast the aristotelian science with galileo's replacement in aristotelian science things work according to their purposes in galileo's new science heavenly matter and earthly matter are the same kind of thing the moon is made of the same kind of thing as the earth and things don't behave as they do because they have intrinsic purposes but rather they work as they do because causes act on them matter according to galileo is inert it's not active and how it behaves depends on the causes that act on it rather than its attempt to reach some final situation so here's a nice uh illustration of aristotelian explanation and how in the 17th century it was being rejected so imagine you've got a siphon pipe like you have at school there's water in the top beaker and that's rising up the siphon pipe and falling down into the bottom beaker how does that work well the aristotelian explanation was that we get water falling down on the right hand side of the pipe because it's trying to reach its natural place closer to the earth that would leave a vacuum a gap at the top of the tube but nature abhors a vacuum nature does not like there to be vacuums and therefore water rises up the left hand side to avoid there being a vacuum so you can see it's a purposive explanation and mollier in le malade imagineer ridicules this kind of explanation so a doctor is asked why does opium make one sleep and the answer is because it contains a dormative virtue whose nature is to make the senses sorry hopeless why does opium make you sleep because it contains something that's sleep inducing right it's not any kind of explanation in the same way nature abhors a vacuum what does that mean it just means vacuums don't occur it's not telling you it's not giving any explanatory account of why so in place of this kind of teleological physics where we say oh nature is trying to achieve a particular kind of thing and we just have to take that as a given thinkers from galileo onto newton uh instead saw the paradigm of scientific explanation in terms of causal explanation where you explain what's pushing the thing on its way rather than looking in terms of the end point to which it's going and the paradigm of such causation is mechanical contact and motions become calculable mathematically and this seems um significantly better in various ways we actually get what look like genuine explanations as to how things behave we get laws of motion which are quantitative where we can calculate where we can see that things really do behave in the way that's expected it's not just an arbitrary supposition that such and such will happen we can see why it happens it seems intelligible if you think in terms of mechanical contact when say one billiard ball bashes into another billiard ball we think we can understand why that makes the other one move it's not that the second ball is trying to achieve any purpose it's rather that the first one is pushing it along that seems genuinely intelligible and as i say it's precisely predictive and testable so lots of scientific advantages but notice that we do have a problem here galileo was claiming that mata doesn't strive left to itself it's just inert material things like billiard balls will just carry on moving in a uniform direction at a uniform speed unless they're acted upon by a force that's why when you push the sledge on the lake it will just continue going until it's acted on by a force for example air resistance friction it will eventually stop and the heavenly bodies are according to galileo made from exactly the same kind of stuff as earth but then we have a real problem why is it then that the moon orbits the earth why do the planets orbit the sun you may get a nice explanation of things like billiard balls but the heavens still seem to remain a significant problem and this is way where descartes comes in and he will occupy a fair bit of time in what we do in in these lectures he's obviously he's known as the father of modern philosophy but just now i'm going to focus on the physics so descartes uses some of the skeptical arguments the rediscovered skeptical arguments from those manuscripts i mentioned those heretical manuscripts raising all sorts of skeptical worries that had been suppressed for centuries in the west but then were rediscovered and he used these arguments to attack the aristotelian orthodoxy he basically said i'm only going to accept a theory that can stand up against skeptical arguments and hence i'm not going to expl to accept a theory whose only support is tradition and authority he goes along with galileo the mechanical philosophy but he gives a grounding for it in a theory of matters essence i'll explain that in a moment he also famously makes room for mind so descartes is the original cartesian dualist he thinks that matter and mind are quite distinct and they are different laws apply to those now we often think today of descartes as being a philosopher who you might describe as a spookist he believes in spooky things these non-material minds actually at the time the biggest impact of descartes was that he was taking mind out of physical science he was saying that the physical things do not have anything like a mind in them they are not moved by purposes and so forth so in terms of the physical science the more important point about dividing matter from mind is to separate them and remove mind from the domain of physical science uh he was a main major natural philosopher this isn't so well known we tend to think of descartes as a a conventional philosopher now but his focus was just as much on the physical world uh as on the arguments for which he's so well known now in the meditations one thing you may have come across the coordinates you learn at school the x and y coordinates they're called cartesian coordinates that's because descartes who was a great mathematician invented them you can see that he made various other discoveries too just very quickly here i'm not going to go through this in detail but when you're looking when you're reading the meditations as i hope you will it's on your reading list here are some sort of highlights as you go through he's looking for a basis for philosophy that is not appealing to authority as i've said he wants argument sufficiently strong to refute the skeptics he famously comes up with the statement i think therefore i am the one thing i can be absolutely certain of is my own existence very importantly two he goes on to say by pondering physical objects and he gives the example of a piece of wax i can see that by through my mind i am able to understand its nature and the nature of matter he says is simple geometrical extension what makes something matter is that it's extended in space unlike our minds which are unextended and then he goes on to prove the existence of god to say that since he's created by god he can ultimately trust his faculties but i want to come i want to focus more on this issue of matter as geometrical extension he thinks that because mata is just extended stuff it follows as galileo had claimed that bodies are just passive they simply act on are acted on by other things they have no intrinsic purposes they are simply passive or inert but fascinatingly and importantly this gives an explanation of that puzzle that we were left with how is it that uh the moon orbits the earth and that the planets orbit the sun well if the essence of matter is extension if matter is just extended stuff extended in space it follows that wherever you have extension in space you have matter it immediately follows that the universe is a plenum there is no empty space because if the essence of matter is simple spatial extension then as i've said wherever you have expat spatial extension you have matter now what follows imagine that you have a very large soup turin it's absolutely full of soup and you're stirring it then as you push on your spoon it pushes the soup here does it leave an empty space no because the soup behind comes in to fill the space and that has to happen if your turin is absolutely full of soup and you are stirring it then pushing in any place has to uh force the the whole lot round so that it fills in the space so all motion in within this soup terrine will take the form of vortices whirlpools so if space is completely full of matter which it must be because the essence of matter is just extended extendedness and therefore where you have extension you have matter it immediately follows that all motion in the universe all physical motion must take the form of vortices and if that is so then it's no longer difficult to explain why you have the moon moving around the earth in a vortex the planets moving around the sun in uh vortices and lots and lots of other little vortices which make up uh our own bodies and the wider world and there i will stop thank you very much

Channel: Philosophy Overdose

Views: 1,780

Rating: 5 out of 5

Keywords: Philosophy, History of Philosophy, Descartes

Id: ssEOfnemJ_M

Length: 53min 47sec (3227 seconds)

Published: Wed Nov 18 2020