Right, welcome to the second lecture on general philosophy.
This completes the sort of general survey of historical change in concepts, which is mainly occupying these first two lectures.
And I want to stress that I consider this history to be absolutely crucial to getting a proper understanding of
the topics that we cover in general philosophy that will become more evident as we go through the pictures here.
We've got Descartes, of course, on the left, then Thomas Hobbes, who enters the story today.
Isaac Newton, Charles Darwin and Albert Einstein.
Now you may well think that at least three of these are far better known as scientists than philosophers,
but their ideas are of profound significance for philosophical thinking about these things.
OK, first of all, a reminder, we came across Descartes last week.
He had a brilliant idea, a synthesis that brought together the ideal of mechanism with an explanation of one
of those these very puzzling phenomena the motion of the Moon around the Earth,
the planets around the Sun. He denied the Aristotelian idea that bodies in nature, like stones or planets,
are motivated by something like purposes striving to reach the centre of the universe or something like that matter for Descartes.
As for Galileo is simply passive.
His idea is that the essence of matter is extension extended ness in space, and that immediately means that space is a planet.
There is no empty space because wherever you have extended space, you've got matter.
It follows that the motion of matter can only go in vortices.
And therefore, you've got an explanation of the motion of the planets around the Sun and so forth.
As for mind, the essence of mind is quite distinct.
The essence of mind is thinking mind is not extended. Matter is so it's a completely distinct kind of substance.
And importantly for some, at least, as he presented at the beginning of the meditations, this makes room for immortality.
He's very keen to promote his text as suitable for teaching in religious seminaries and so on.
So making space for immortality is pretty crucial.
But actually, in many ways, the most important aspect of Descartes work was taking mind strivings and things out of physical science.
So we're going to be talking quite a bit today about physical ism.
And I want to, first of all, introduce that in contrast with Cartesian dualism named after Descartes.
So Cartesian dualism, you have physical bodies that consist of material substance.
You've got mines quite distinct, consisting of immaterial substance thinking stuff.
By contrast, materialism nowadays it tends to be called physical ism is the view that there's only one kind of substance,
namely material, substance or physical substance.
Notice, although I won't be saying much about this today, this is compatible with having a distinction between physical and mental properties.
So you could say we consist entirely of material substance, but amongst our properties are mental properties as well as physical properties.
So you can have a dualism of properties compatibly with being a materialist.
So Thomas Hobbs comes in as a notorious figure, better known today for his political theory.
He's still very, very prominent in reading lists on political theory, as many of you may know.
So we have his portraits in Hartford College because he went to Modelling Hall, which morphed into Hertford College.
So he's an Oxford man. He he was like Descartes, a pianist.
He believed that the world was full of material substance.
But he denied that mind is immaterial. So in corporeal substance, he claims, is just a contradiction in terms.
And you can see here he's making fun of Descartes when men make a name of two names whose signification is a contradictory and inconsistent.
The result is but insignificant sounds as this name and incorporeal body, all which is all one an incorporeal substance.
He's taking Descartes theory, and he's providing it in Leviathan as a paradigm example of an abuse of words.
Now, this was obviously very shocking. The obvious reason if you are a materialist, it makes it very hard to maintain either a belief in God.
I mean, it follows that God is a material substance, which for most people is going to be tantamount to denying that there is a God.
But also, it obviously seriously threatens immortality.
So in the 17th century, this is thought seriously disruptive to morality.
If you deny a future state, a heaven and [INAUDIBLE], then what motive is there for people being moral in this life?
So lots of philosophers, as you can see him, these are only the most prominent ones lined up to refute Hobbes.
The Leviathan came out in sixteen fifty one. We have a large number of responses to Leviathan attacking Hobbes materialism.
Now, the main argument against Hobbs, and this still resonates, by the way, in 21st century debates,
when people ask questions about whether computers could think or whether they could be conscious.
A common argument that comes out is that there is something inconsistent with
the idea of matter thinking and back in the 17th century and the 18th century.
Indeed, this went along with the idea that we have seen from science that matter is inert.
Aristotle was wrong. Galileo was right. Matter just keeps moving at the same speed in the same direction unless it's additive acted upon by a force.
Of course, that's a major plank of Newton's theory that will come along later so that if matter is inert,
then it can't have active powers like thinking. And in that case, it follows that the world cannot be purely material.
We cannot be purely material indeed. But notice that this argument assumes that we can understand the powers of matter a priori.
Now it's worth clarifying this term a priori, it's a very important one.
It crops up a lot in philosophy. So I'm going to give you a dictionary definition of it here.
A belief or claim is said to be justified a priori. If it's epistemic justification,
the reasonable warrant for thinking it to be true does not depend at all on sensory or introspective or other sorts of experience.
Whereas if it's justification does depend, at least in part on such experience, it is said to be justified a posteriori or empirically.
This specific distinction has to do only with the justification of the belief and not at all with how the constituent concepts are required.
OK, that last sentence is very important. So a standard example of an API where I truth is all bachelors are unmarried.
OK, we define a bachelor as an unmarried man, so we can know a priori that all bachelors are unmarried.
Now, clearly, we cannot get the concept of a bachelor except through experience.
If you didn't have any experience, you wouldn't have the concept of a man. You certainly wouldn't have the concept of marriage.
But the crucial point what makes it a priority is that having acquired those concepts,
you don't then need to consult experience to find out whether it's true or false that all bachelors are unmarried.
You can just see by examining the concept that that's the case. OK.
So an API where I truth is something that you can know to be true without any justification from experience.
And this argument against jobs that matter could not possibly think is relying on an April right claim because it's not saying look by experience,
we can tell that matter doesn't think. And that's no good because jobs is going to say.
On the contrary, we know by experience that matter can think because I'm a matter and I can think so.
This argument is based on an a priori claim about the powers of matter, and we'll see that that's a problem.
We'll come back to that a little bit later. So Robert Boyle, a very, very influential scientist in the 17th century,
and he was actually a pioneer of chemistry, and he was very much a champion of the mechanical philosophy.
But unlike Descartes and Hobbes, he was not a plainest.
He did not think that the universe is completely filled up with matter.
He thought there was stuff called universal matter formed into corpuscles what we would think of as atoms.
But the word atom in those days was associated with Greek atom ism, which was notoriously atheist.
So he preferred the word corpus Galarian ism. So you've got corpuscles little think of them as atoms made of stuff, universal matter.
But they are inside a void. So the universe as a whole is empty,
except where you have these material corpuscles and every thing that we see in the world is the result of interactions of these little corpuscles.
And clearly that the kind of corpuscles that make up gold are going to be different from the corpuscles that make up LED.
Maybe a different size, maybe a different shape, maybe put together in a different order.
But essentially, you've got something like an atomic theory. But importantly, a distinction between empty space and matter.
Another bit of the scientific story, which we'll see this all comes together very shortly.
So a chuckle, Tycho Brahimi, a Danish astronomer,
had built an observatory on an island and he was a nobleman, and he created astronomical instruments.
Naked eye that were far, far more accurate than any that had previously been devised.
And over many years, he plotted the paths of the planets and then Yohannes Kepler, who started out as brought his assistant, inherited all that data,
but did some very clever mathematics and discovered that the data were actually most
consistent with the hypothesis that the planets move around the Sun not in circles,
but in ellipses. With the Sun at one focus of the ellipse, I've drawn a little image of something what it's like now.
Kepler published tables, astronomical tables based on his calculations, predicting where the planets would be in the sky at any particular time.
Now, prior to this, the tables that have been published based on Aristotle's theory and later on,
Copernicus, which was sort of it's still fundamentally based on circles, were only of limited accuracy.
And sometimes you might look look up in the sky. You see a planet in roughly the right place, but maybe it's five degrees out.
Kepler's tables were more than a thousand times more accurate.
They were phenomenally accurate. And you've got to remember that this was done without the aid of telescopes.
Quite remarkable. Now over time.
As people became aware that these tables were so fantastically accurate,
it became accepted that actually the planets were moving in ellipses around the Sun, not circles.
I mean, Galileo had already done for the Aristotelian theory.
What Kepler did was show that the astronomical bodies do not move in circles, but ellipses.
And this is where Isaac Newton comes in, because what Newton did was to show that if you have a force between bodies which is proportional
to their mass and inversely proportional to the square of the distance between them.
And if you have one very large body and one very much smaller body,
the smaller body will move under the action of that force in an ellipse around the larger body with the larger body.
That's a focus of the ellipse that's on the assumption that force equals mass times acceleration.
Moreover,
he showed that the same equations with the same constants worked for cannonballs on Earth and worked for the Moon and worked for the planets.
Another thing he showed. This is all in his famous Principia Mathematica.
He showed that a vortex cannot generate elliptical motion.
So Descartes theory is in the vein. Now, all this might seem some distance from philosophy, but think back to that important argument against Hobbs.
And as I say, that's an argument that still resonates today in discussions of mind and consciousness.
Newton has postulated a force, he's got very strong evidence for it, too.
It fits with the data brilliantly.
He's postulated a force that acts as a distant at a distance between bodies with no intermediate mechanical connexion.
But this seems completely unintelligible. OK, Descartes, in arguing against the Aristotelian CID, said this this idea of strivings,
you know, a body striving to reach the centre of the Earth is ridiculous. The body would have to be conscious.
It would have to know where the centre of the Earth is, what exactly the same applies to gravity.
If you've got two bodies in space, how can this one be attracted to this one unless it somehow knows where it is?
If you've got no mechanical interaction between them, how would you explain gravity?
Now, the real problem here is it's not so much.
OK, well, we just have to accept this unknown for this strange force gravity.
You know, we have evidence that it exists, but we've no idea how.
What's the problem with that? Well, the problem is that if matter can have an active force like gravity,
why couldn't it have an active power like thinking once you allow that matter can have all sorts of properties that we can't understand.
Materialism is far harder to attack.
So Newton famously said hypotheses non thing go that can be interpreted in various ways, but he seems to be saying my equations work.
I'm not going to worry about what the mechanism is, how it all works until I've got some data to base that on.
But as I say, it has a real consequence for the argument about materialism.
So one thing I want to really emphasise here is that scientific progress over the early modern period
systematically pushed us progressively away from a natural and intuitive understanding of things.
And this is carried on in later science. So Aristotle started from the very natural nice idea that we can understand the way things in nature work,
both on the assumption that they've been designed intelligently and that they are crazy, intelligent themselves.
They strive to achieve certain purposes. Galileo refuted that Descartes tried to get a theory which was compatible with simple mechanism,
whereby things work in intelligible ways by one piece of matter,
pushing on another in vortices and so we can understand where we feel that's intelligible.
And then we get Keppler and Newton showing that that's that just seems to be wrong.
OK, the mathematics just doesn't work with empirical observation,
so we end up having to have this gravitational force, which seems completely unintelligible.
I mean, we can understand it, understand it inverted commas to the extent of calculating what its upshot is.
But we've no idea at all where it comes from or how matter generates it.
And I'm not going to describe this in any detail, but we see the same in 20th century physics.
All right, general relativity, we get the idea of space being linked intimately with time and somehow being curved,
which most of us find extraordinarily difficult to get our heads around quantum mechanics.
Fundamental particles will all be particles. They're very weird.
Their behaviour is describable, but it's not really intelligible.
So although physics retains the goal of accurate prediction and explanation of a sort, it seems somehow it's how to give up on making sense of things.
So just spell it out. In science, we often talk about explaining something when we have formulae that generate the observation and we can say,
Oh, that observation is consistent with our theory because look, we've done this calculation and it works out.
We've explained it. That's not the same as rendering it intelligible.
If the equations that we're using are ones that seem deeply unintuitive to us, then we may resist the idea that we really understand what's going on.
And obviously, philosophers can ask serious questions about this notion of understanding.
I'm not going to have time to go into that deeply now. I just want to illustrate for those of you who might not know about it.
And here is a simulation of the two slit experiment.
So Thomas Young devised this experiment, and what he found was that if you take a source of light, by the way, it's monochromatic light.
I'll explain the colours in a moment. You've got a single source of light there, and the light is hitting a screen which has two slits in it.
A man at the back of the apparatus, there's another another screen and.
What you get if you shine light through like that, as you can see at the top.
You end up with bands of light.
OK, now that was taken to be very strong evidence for a wave theory of light.
And now, by the way, the colours are indicating where we are through a wavelength, so we kind of going round the colour spectrum each wavelength.
And so they enable me to highlight the interference and the brighter they are, the the bigger the amplitude.
So what's going on here is if you imagine dropping two pebbles into a pond some distance apart.
Each of the pebbles will cause a wave moving out from where you've dropped it.
And if you've got waves from this pebble and waves from this pebble, then when they interact, they can either do so destructively.
So this wave is high up and this one's in a trough and they kind of cancel out.
Well, sometimes you can have a trough in this wave and a trough in this one and you end up with a deeper trough.
So the kind of pattern you get from this interference is like that, and you can see it nicely explains where we get light on the screen at the back,
that's where the the two light sources are constructively interfering rather than destructively interfering.
OK, well, that's very nice. But then it was discovered early 20th century that a light kind of comes in particles.
You can you cannot get less than a certain amount of any particular wavelength of light light particles called photons, the sort of packages of light.
And whenever you try to detect light, you only ever detect it in terms of these photons.
So if you take a a faint enough light, you will only ever detect it at one particular place.
Now, once that's discovered, we can rethink our experiment and we send the light through the apparatus.
One photon at a time. In other words, we make sure that the light is so weak that at any particular time, we only detect this at one point.
If we put detectors there. And what's rather surprising is that we still get an interference pattern.
Now, that's weird, right, because we're only sending the light out one photon at a time.
It can only go through one slit at most. And yet somehow we're still getting an interference pattern.
That seems spooky. All right, well, let's add detectors to the.
Two slits.
So now we're sending individual films through the apparatus, but we've added detectors so that we can tell which slit the photon is going through.
And sure enough, it only ever goes through one. But now, as you can see, the interference pattern disappears.
So it's very odd you try to think of photons of light as particles or you try to think of them as waves.
And either way, I'm afraid our natural understanding fails to do it.
If you have to think of them as some strange mixture of particles and waves, something very unfamiliar to our experience,
we can do the mathematics, by the way, where we show probability distribution.
You get a different. So we can work out. We can do the mathematics to explain what will happen.
Of course, that maths is built into this computer programme, but trying to get an intuitive understanding of it,
trying to think of it in terms of either waves in water or little billiard balls or whatever, just completely fails.
So. That's a very important lesson, as science has developed.
It's actually shown serious limitations to our intuitive understanding to explain how the world fundamentally is.
OK. Let's now go back to physical ism.
So the kind of physical ism that Thomas Hobbs adopted, materialism, 17th century materialism seemed very straightforward.
Everything that exists consists of matter and matter is spatially extended uniform.
Solid stuff. Whose causal interactions are purely mechanical.
OK, so people like Descartes and Hobbes knew what they meant by matter.
Then along came Newton, and matter becomes a bit more complicated.
Now we've got forces acting on it. Forces like gravity, where we can't really render intelligible how that works.
We can produce equations, but we can't give any commonsensical understanding of why one body attracts another across millions of miles.
Of course, after Newton with modern physics, we find that matter isn't any solid, uniform material stuff.
It's not like Boyle thought you haven't got corpuscles made of universal matter, differing only in their shape, size and texture.
Actually, you've got a variety of fundamental particles.
Some of them are mass slits. Some of them seem point like they have properties like charge and spin, even strangeness.
And they operate within a space time continuum relativity, which seems from quantum mechanics to be in deterministic.
So the Commons, when we think of matter now, when we discuss physical ism, you know, 10 physical stuff produce mind.
We're asking a different kind of question from what Hobbes was asking because we've got such a different concept of matter.
And this leads to something like hemp, something called Hemphill's dilemma.
So take the claim everything in the universe is physical.
There is no non-physical stuff in the universe. And what does that claim mean?
Does it mean everything is physical in the sense that we currently understand physical?
Well, that's probably false because our current physics is probably false, at least in part,
not least because general relativity and quantum mechanics have not yet been rendered consistent.
So it's very unlikely that everything is physical in a way that conforms to our current physical theory.
On the other hand, if we mean everything is physical in the sense of conforming to what the ideal eventual perfect physical theory will be.
Well, then it begins to look kind of true by definition that everything is physical because maybe in that true theory,
you know, everything will be in there, including minds, by the way.
And why not? So it's very, very difficult to put the thesis of materialism or physical ism in a way that doesn't beg questions.
We think we understand what we're saying when we say that everything is physical, but actually it's not so clear that we do.
OK, we'll return to this important question Mind-Body physical exam in a later lecture.
I now want to talk. About our understanding of our own place in the world and here, Charles Darwin is the key figure.
Now you may think find it odd having quite a lot on evolution in a lecture about general philosophy.
But I want to suggest to you that actually all six of the topics concerning general philosophy can be illuminated by thinking in terms of evolution.
Because with all of these topics, we are applying our intelligence to try to understand difficult problems.
And if our intelligence is itself the result of an evolutionary process.
Then that sheds light on how far we can expect it to be able to get to the bottom of these things.
And there are some more thus far more specific Connexions that I'll complete.
OK. So there are obvious similarities between humans and animals, people that obviously recognise these forever.
But before Darwin, humans and animals were thought to be radically distinct.
Man is made in the image of God. Animals are lower down in the ladder, according to Aristotle.
Man is uniquely a rational animal that sets us apart from all the rest,
and this kind of idea was systematised in the great chain of being, of which there is an image there.
So this is Aristotle's ladder of nature systematised by a later philosopher near Neo Platon.
It's called Platini's. And you can see that that there's the hierarchy in which he puts things all fitting neatly into the divine world order.
Descartes again, thought that was a radical distinction between humans and animals.
The beasts have no reason at all. They have no intelligence at all. Animals lack reason, perhaps even thought.
But nevertheless, physically, they're similar to us in certain respects, the physical bodies act in many ways.
Similarly, but they don't have the immaterial mind.
Now along comes Darwin, and I want to give credit here also to Alfred Russel Wallace,
who came up with the theory of natural selection up more or less at the same time as Darwin, actually a bit later.
But he was quick to get it out, whereas Darwin had been pondering this for years and years and years, collecting loads of data but not publishing.
Darwin was reluctant to publish because he could see that his work would be
extremely controversial and dreamily troublesome for those who are religious,
including in his own family. But along came Wallace, he wrote to Russell.
Sorry. Along came Wallace, he wrote to Darwin, said, Here's my theory.
Darwin realised it was the same as his. And they presented together the theory of natural selection.
So kind of joint discovers both of them, interestingly, had been inspired by a clergyman,
Thomas Malthus and Thomas Malthus wrote an essay on the principle of population,
basically pointing out that animals the the the pace at which a population increases will generally be a geometric series.
In other words, the more the larger population is, if it continues to breed at the same rate, then you will get an exponential increase in population.
Now, that means that even if you somehow manage to increase the food supply by a constant amount year on year.
Eventually, the population is going to outrun the food available.
Now, I think it's quite hard to appreciate just what exponential growth does.
So I've got here a little simulation.
So imagine a population of rabbits and that population of rabbits is just a hundred of them and they are bang in the middle of the globe,
you see there. OK, now we've got it so that these rabbits breed at what's actually a fairly modest rate for rabbits.
If you've come across the habits of rabbits.
They're growing at the population is growing at a rate of 10 percent per generation, just 10 percent with two months per generation 60 days.
OK. And let's see what happens when we set this running.
One thing about these rabbits, they have no predators. They don't get disease and they can spread around the world quite quickly.
The only constraint on them is you cannot have more than one rabbit per square foot or if your metric about nine per square metre.
Okay, so here's here we go. Right.
That took fifty two point four years. Now that's exponential growth for you.
Now, one way you can think about evolution is that unchecked, pretty much any biological species is going to do that.
So you've got immense competition, only a tiny proportion of the possible offspring or the possible offspring of offspring or offspring of offspring,
offspring of offspring and so on. Only a tiny proportion will survive.
Now, if that so. What's going to determine which one survive, is it going to be me a chance?
Well, there'll be a lot of chumps in it, of course. But when you've got that much selection taking place.
Any factor which biases the chance is going overtime to have a very big effect.
OK? There will be some which stand a slightly better chance of surviving because they're faster
or stronger or more immune to certain poisons or able to digest more things or whatever.
And when you've got that level of competition, those advantages are going to tell.
So. This is what natural selection is.
If animals or plants have these features, the characteristics are largely inherited with some random variation.
So obviously, you can't invariably predict that taller parents will have taller kids.
It doesn't always work that way. But by and large, the taller the parents are.
That's all of the kids are going to be right. Some of these characteristics are relevant to survival and reproduction.
That's obvious out there in nature, where gazelles are being chased by cheetahs and so forth,
being a little bit faster as a gazelle gives you a much better chance of survival.
If you can outrun the other one, you're less likely to be caught.
And if you're a cheetah, being a little bit faster can enable you to catch a mule where otherwise you wouldn't.
They live in a competitive environment.
Well, the moral of the programme I've just shown you is that more or less everything in nature lives in a competitive environment.
There is no way that you can have pure stability and no competition.
Not in practise. And then natural selection is pretty much inevitable.
It's pretty much inevitable that as the generations go on, proportionately more will will have what we now call the genes we the inherited the
code that creates the inherited characteristics that are more conducive to survival.
Now, some things can hugely speed this up. I've given the example of cheetahs and gazelles and where you get co-evolution.
But this process can go really, really fast if you've got gazelles competing against cheetahs.
Then if you're a gazelle and you are slower than usual, nature is going to have its effect on you very quickly in the form of a fast cheetah.
Unlike wise, the fast cheetahs are going to get a pretty quick reward for being faster.
So evolution will run really fast. And again, one can simulate this with computer programmes,
and it's very apparent how introducing this element of competition between two competing species radically can speed things up.
Sexual selection is also well worth introducing here.
If you have sexually reproducing species, then typically you've got an asymmetry between females and males.
Males are capable of having lots of offspring, females far fewer, and therefore females tend to be much more selective.
And if females choose their mate according to particular characteristics,
and the obvious example is pigeons choosing peacocks with impressive tails that can drive a runaway process.
Basically, if you're a peacock or a pigeon, if you well.
More or less, any person is going to be able to mate, but amongst the peacocks, some will do very well,
and some, I'm afraid, will end up without a partner because the hens are being selective.
So the competition is far more amongst the males than amongst the females.
And as a result, you can get this, you know, the absurdity of a peacock tail, which must hinder the peacocking getting away from prey.
But because it's so effective in attracting P hens that over balances and any negatives.
OK, so evolution is a very sophisticated theory, there's the I've only mentioned a few of the parts of it.
It's a very powerful. It explains a huge amount.
I'm going to spend a fair bit of this lecture now just outlining some of the evidence for evolution and drawing a moral from this.
I think it's well worth knowing this because there's a lot of misinformation about this.
People like to say, Oh, evolution is only a theory. I talk about as though it's less than certain.
Even when Darwin wrote of the origin of species, the the evidence he had was very, very strong.
But the evidence we now have is absolutely overwhelming because we have found so much that fits in perfectly with the evolutionary story.
We've got the fossil record, we've got vestiges that is evidence from the bodies of creatures that now exist.
Which features that don't make any sense in terms of how they now live, but make perfect sense when seen as inherited from previous species.
Got evidence from embryology and development the way in which foetuses develop, which to some extent recapitulate an evolutionary history.
We've got evidence of biogeography where the animals and plants are distributed around the world, and most recently, we've got evidence of genetics.
So basically, once once DNA was discovered and once people started analysing the genetic sequences,
all lo and behold, it all fitted perfectly with an evolutionary story.
So you can. There's lots of sources for this. I'm just going to mention a couple of them.
One of them is obviously Wikipedia.
The other one, I think this is an excellent book, and the authors kindly gave me some images for me to use in this lecture.
So the images here, unfortunately, won't be able to get much from them on the handout.
But the important thing is is the page numbers. If you if you want to follow this up, go and look at the book.
You can see where these things are. So there are lots of transitional forms, when Darwin wrote.
People were able to say of him. Hang on.
If you're right, there should be lots of intermediate forms of animals intermediate between the ones that we now see.
Well, those have since been discovered. Here's one example Tiktaalik discovered in 2004.
It seems to be a genuine intermediate between a fish and an amphibian.
And the year after Darwin wrote Archaeopteryx, famously intermediate between a small dinosaur and a modern bird.
There are lots of others. Here's one example in the highest and sort of ancient pig like animal.
And the modern whale and intermediates have been discovered all the way through.
And this makes sense of why the whale has a vestigial pelvis and hind limb wouldn't make any sense if the whale was a fish.
But explaining the whale as evolved from an animal somewhat like a pig does explain it.
Humans and apes again in Darwin's time. There wasn't this richness of intermediate forms.
Now there are. And you can see at the top left you got Homo sapiens, that's us at the bottom right, you've got the chimp.
And there are a load of intermediates. I mean, the the story of human evolution is a complicated one, the seem to be lots of different species,
and it's not absolutely clear, you know, which descended from what. And so on.
What is clear is that there are lots of intermediates. Biogeography, well, there's lots of evidence for continental drift from Earth Sciences.
I mean, for example, ocean rifts where you get spreading, where the magnetic bands on each side of the Rift are kind of match up and.
The theory of continental drift became very well-accepted in the 60s and 70s before that had been extremely controversial.
But if you put that evidence together with biogeography where fossils are to be found,
where different kinds of trees are to be found, it makes lots of sense of what would otherwise be senseless.
Instances of bad design. This is really vestiges, this is cases where we find that modern animals, including ourselves,
have certain aspects which wouldn't make very good sense from the point of view of an intelligent designer.
And one famous example is the blind spot in the eye.
I mean, another is how humans give birth, which is notoriously painful and difficult and potentially carrying a risk of death in nature.
But in another, a particularly vivid one is this nerve, the the left recurrent laryngeal nerve, which goes all the way down and back again.
And that doesn't make any sense at all. From a design point of view, but it does make sense if you see as is being evolved ultimately from fishes.
OK. I've not gone in detail through DNA evidence, but that I think is also tremendously important.
So I just want to point out here an important consequence of all this.
You will find people who want to deny evolution. Typically, they want to do so on religious grounds.
But here is why I think if if you are religious, you should not be going that way.
I don't actually think that evolution shows religion to be false.
It doesn't show that there's no God. It may show that certain rather narrow fundamentalist views on religion are false ones that claim,
for example, that Genesis gives an accurate story of the creation.
But then, since there's more than one story in Genesis, that's fairly easy to conclude anyway.
But here's the problem if you think there is a God who did not operate by evolution, but yet gave us all this evidence of evolution in the rocks,
in the fossils, in the distribution of plants in our own DNA, then you have to believe in a creator who actually is deliberately deceiving us.
Because why else would all that false evidence be there? And if you believe in a creator who can deceive us,
then you've got no reason to believe that holy book on which you are basing your denial of evolution.
You can't have it both ways. The evidence is there. If that was put there by a designer, then it was put there by a designer who was lying to us.
In which case you could lie in other respects as well. Okay, so I want to explain why I think evolution is completely incontrovertible.
All right. This is not a controversial view amongst people who know the evidence.
What's the significance of it?
Well, if we are continuous with animals and if our faculties have evolved in response to selective pressures over the multitudinous generations?
Then that tells us something about our rational connexion with the world.
And when we ask questions like, what can we know, how are we able to predict things about the world?
What is the nature of personal identity? What is the nature of freedom or mind and body?
If we bear in mind that the brains with which we are trying to get to the bottom of these things are evolved organs.
Then we shouldn't be so surprised that sometimes our intuitive judgements about
things may prove to be radically at odds with the real nature of things.
Why be surprised that quantum particles act in ways that we find completely counterintuitive?
That's exactly what you'd expect, because in the evolutionary scenario, an ability to understand quantum particles played no role at all.
What was important was to be good with medium sized objects like rocks or spears.
Being good with quantum particles would have been of no use to you at all.
It would just be a waste of brain space. And this goes for a lot of these different topics.
So I'm from the next lecture, we'll be focussing very specifically on these various topics,
but I hope as we go through that you will bear in mind some of the lessons we've seen from these first two lectures,
which I think very importantly on every single one of the six topics. Thank you.