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 figures will be considering, well,
Monty Python's God at the far left, then Plato and Aristotle Galileo and Rene Descartes.
Let's start by asking what general philosophy is.
Well, it's contrasted with ethics or moral philosophy.
It is focussing 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 enquiry 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 Rennie 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 focussed 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 linked 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 worldviews that go back to 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, the 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. An addition is shown at the top there on the right.
David Hume's enquiry 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 scepticism will be coming across.
Descartes sceptical 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 playing a large role with regard to scepticism.
He's an advocate of what he calls mitigated scepticism, 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 the evil we will come to towards the end of the lectures. Uh, 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 Hobbs and David Hume advocated compatible ism,
which is still a very popular view of free will and took a naturalistic view of man is 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 some previous lectures that I did, these were recorded in two thousand and nine to 10.
You can see they're freely available and they're slightly different from the current lectures 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 golden 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 aimed to complement those.
These lectures contain more thematic material, drawing more connexions between subjects and more links.
Also with other Oxford disciplines that you may be studying alongside philosophy.
OK. Let's go back now to that question of why we should bother with philosophers history.
Why does history play such a large role in our introduction to general philosophy?
If you want more detailed discussions in the 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 there on the David Hume dot org website.
And incidentally, all of David Hume's philosophical works can be obtained free from David Hume dot org,
as well as lots of pictures 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 worldview that you get in the 1500s,
say, and the 17 and 18 hundreds 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 compatible ism.
So if you're discussing freewill, an important position is compatible ism, 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 Hobson Hume got their first.
Perhaps even more importantly,
these were very great minds that the people whose works you will be reading from the 17th and 18th centuries were absolute undisputed geniuses.
Moreover, they were addressing these problems for the 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 specialising in one particular area
of philosophy invariably find that their study links to lots of other areas.
Now, one problem with studying philosophy as it were in disciplinary silos like 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 focussing 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 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 specialised journal.
So by looking at the way that their ideas interlock in history, you get an appreciation of these wider connexions.
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.
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 well as students and ordinary people in the streets 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 how God functions in his system.
You shouldn't be saying, Oh, well, he's got different beliefs for 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 focussing, 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 focussing on there for 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,
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 contradistinction with the mediaeval and ancient world.
And although, 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,
et cetera. 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 combine degrees.
We have its 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 emphasise 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 favour 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 the when the Roman Empire became Christian.
Thanks to Constantine, a lot of ancient philosophical schools were basically stamped out.
So Plato's Academy, for example, have been going for eight hundred years.
And it just stopped. There we will be seeing that in the period that we are 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 the Christian background,
and then we'll see how problems emerged in the early modern period, which essentially brought about the birth of modern philosophy.
OK, well, most of you are probably familiar with the the Genesis story in the beginning,
God created the heavens 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 a man was created, he was 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.
OK. Genesis Chapter two 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 Tilly ology with purpose.
The world has been created by a God who's put us there in his image for a reason to do his works.
And you can see an 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 are most popular with early Christians Plato,
Neo, Plato and some have huge impact on the development of Christianity in the mediaeval 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 clear logically 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 water trees fall to provide shade?
What is rainfall 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 teleological.
So as I say, it's not surprising that the most influential early philosophies tended to be very teleological inform.
And just a couple of examples which match with this general idea, Plato, his famous theory of forms,
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.
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 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, prior to 16:00, the standard account was this 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 centre, 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 centre 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 a particular final ends.
So Aristotelian science, we've got these four terrestrial elements, as I've said, they naturally move to reach their 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, the heavenly bodies.
If you look up at the Moon and the stars and the sun and planets, they don't fall to Earth.
They must therefore be made of something different. And Aristotle called this Aether this fifth element.
And the reason why they move in circles. Why did they have any body to move in circles?
Because that's the closest they can get to the perfection of an eternal, eternal creator?
So again, we've got a purposive account of why things act as they do.
So here is is one image of Aristotle's universe.
You can see you've got water on Earth, air and fire, then the sphere of the Moon and everything beyond the sphere of the Moon is made
of Aether and you've got the planets moving on sort of crystalline spheres.
And the fix stalls 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 map on Monday from Hereford Cathedral.
So this map was dated around 13:00. And it's based on the writings of a pupil of Saint Augustine of Hippo.
And those writings go come from about 400. So we've got a work being produced in 13:00 based on an authority 900 years earlier.
And you can see that the map puts Jerusalem at the centre. I've marked Roman Hereford. and Noah's Ark and Eden and Babylon.
That's the world as it looks in 13:00, and it hasn't changed much for 900 years.
Now, an awful lot changed in the period between the mediaeval world and the period we're going to be looking at mainly the 17th and 18th centuries.
All sorts of things started creating cracks in this edifice, an edifice which was lost 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 fourteen, ninety two, 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 realisation that ancient maps were wrong, I mean,
imagine if you've been brought up to think 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 are a lot of technological changes. I mean, gunpowder came to the West and had a huge impact with regard to the centralisation of power.
It also had a major impact 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 Christian ization of the Roman Empire were rediscovered,
and those had a profound effect in philosophy. Then along came the Reformation.
So in 15 17, 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 condemn them,
you to eternal 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 because Luther's wasn't the only variety of Protestantism.
John 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 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 killing each other with abandon simply because they have a different variety of Islam.
Well, in the 17th century, there was lots of that amongst Christians.
The thirty years war, which raged mainly across Germany, was particularly horrible.
That went on from 16 18 to 16 48. However, we in England saw the Civil War, and these all fundamentally arose from differences in religious doctrine.
In 16 48, the peace of Westphalia came about not through any real decision of the war and certainly not any agreement on doctrine,
but basically it was described as a piece of exhaustion.
The war had so decimated so much 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 print stems 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.
OK. So in those last few slides, I've explained why over this period,
from about fifteen hundred for the next 100 150 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 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, and 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, 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 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, on its orbit because Mars is outside the Earth.
And therefore, as that overtaking is taking place, Mars move 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 to another interesting point is that Venus never appears in the sky more than about 45 degrees.
I think the maximum is 47 seven 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 epic cycles. Now here's an example with Venus.
Imagine that Venus is travelling 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 is circle is itself rotating around the Earth.
So we we have an epic cycle 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 round the Earth,
but sometimes moving backwards. Interestingly, the AP cycles for the outer planets tend to have a duration of 365 days.
Interesting coincidence. Now, Galileo in 16 09 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.
He saw that the Moon did not seem to be the perfect body that had previously been thought.
This aethereal 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 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 AP cycle itself,
going around 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.
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 centre 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 centre of the universe.
If the Earth is no longer the centre 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 realised was that there were lots of other things that Galileo did.
Aristotle could not explain, like the flight of a cannonball.
So ancient accounts had cannonballs firing up under the 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, whereas Galileo realised that actually cannonballs fly more or less in a parabola.
A sledge sliding on flat ice, imagine that you're on a flat 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 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 in a very small ball from the top of the leaning tower of Pisa, and they fell at pretty much the same speed.
I mean, that's probably apocryphal.
It's 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, an 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 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 purpose of explanation. And Moliere in the Mallard, 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 dormant virtue whose nature is to make the senses soporific.
Hopeless. Why does opium make you sleep? Because it contains something that 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 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 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 significantly better in various ways.
We actually get what looked 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 matter doesn't strive left to itself, it's just inert material,
things like billiard balls will just carry on moving in a uniform direction.
It's 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 the Moon orbits the Earth?
Why do the planet's 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 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 sceptical arguments, the rediscovered sceptical arguments from those manuscripts,
I mentioned those heretical manuscripts raising all sorts of sceptical 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 sceptical arguments,
and hence I'm not going to agree 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 in a moment. He also famously makes the mind so Descartes is the original Cartesian duellist.
He thinks that matter and mind are quite distinct, and they have different laws apply to those.
Now we often think today of Descartes as being a philosopher.
You might describe as a spookiest 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.
He was the 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 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 to just very quickly here.
I'm not going to go through this in detail, but when you look, 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 arguments sufficiently strong to refute the sceptics. 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, too, 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 extended in space, unlike our minds, which are on extended.
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 matter is just extended stuff, it follows, as Galileo had claimed that bodies are just passive.
They simply act on are acted on by all the 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 the Moon orbits the Earth and that the planet's 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 planet. There is no empty space because it's the essence of matter is simple spatial extension.
And as I've said, wherever you have spatial spatial extension, you have matter.
Now what follows? Imagine that you have a very large soup tureen.
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 suit behind comes in to fill the space.
And that has to happen. If your tureen is absolutely full of soup and you are stirring it, then pushing it.
Any place has to force the the whole lot round so that it fills in the space.
So all motion in within this soup tureen 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 extended ness 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 vortices and lots and lots of other little vortices which make up our own bodies and the wider world.
And there I will stop. Thank you very much.