2025-04-07 Within Reason #102 - You're Not Smarter Than a Caveman
Duration: 01:55:29
Transcript
Alex O’Connor
Are people, human beings, more clever today than they were 100,000 years ago?
David Deutsch
Of course, we have virtually no evidence about that, but going from first principles and from my feeling of what the situation has been, definitely not. They were definitely our equals in mental capacity and in anything physiological to do with thought or understanding. They were our equals. The difference between us and them is culture and technology. Those are beyond comparison different today, but they have only been beyond comparison different for a few hundred years, since the Enlightenment. Before that, people were much like they had been in prehistoric times.
Alex O’Connor
Well, this is the interesting thing. A lot of people will look to our ancestors and implicitly assume that they must have been pretty stupid. These fools running around just about working out how to use fire, didn’t invent the wheel for thousands, hundreds of thousands of years. They must have been pretty stupid. The question is, if our brain structures are essentially the same, evolution works on an unfathomably long stretch of time, we haven’t had enough time for our brains to significantly evolve since 10,000 years ago, 50,000 years ago. Why then in the last few hundred years in particular? I suppose in the last few thousand years, really, if we’re talking about society, have we managed to go from these helpless apes wandering around in about the middle of the food chain to just dominating the planet to the extent that I can know with a relative level of certainty about the chemical makeup of the interior of stars in galaxies that I can’t even see with the naked eye? How did that happen if not an increase in intelligence?
David Deutsch
I think it’s culture and technology, but there’s another thing to take into account, which is that our ability to do this thing that we do, which I call explanatory creativity, the ability to create new explanations of the world and of other things, that evolved. It’s fairly obvious just from the few data points that we’ve just discussed that it can’t possibly have evolved for what we now want to use it for. It can’t possibly have evolved for creating new explanations because so few new explanations were in fact discovered. A hundred thousand years ago, at that time, well, first of all, we know that they were capable of inventing radio telescopes and advanced theories because inventing campfires involves exactly the same logic and epistemology goal. That’s the same feat. Incidentally, learning human language, the subtleties of human language, is also a similar size feat. We all do that with just the attributes of early childhood. It can’t have evolved for the thing that we use it for now. That is the ability to use. The ability for the faculty for creative explanation can’t possibly have evolved for creative explanation. Otherwise, it would have done what it’s done recently. It would have caused exponential improvement. In fact, improvement in prehistoric times and right up to historic times has been so slow that a typical person did not experience any and never mind effect any. That means if a faculty isn’t used, then it can’t have exerted evolutionary pressure.
Alex O’Connor
Yeah. It can’t be the reason why it came about, but we’ve clearly got this faculty for, as you call it, creative explanation. To be clear, when you talk about creative explanation, maybe we should spell that out for people who are unfamiliar, but we’re kind of talking about the thing that occurs around about the time of the Enlightenment, which is tied up with the scientific method, the idea of looking at phenomena in the universe and trying to come up with an explanation for why it’s the case through things like science. The faculty to do this doesn’t just spring into existence. It must have been there in our brains 100,000 years ago, but because no one was doing it back then, that can’t be what it evolved for.
David Deutsch
Exactly. Exactly. Very few people with, few and rarely. Somebody had the idea to put the flaming branch on the ground and put other branches on top of it to drive off the predators. That sort of new idea was very rare, and so that’s why it didn’t exert any evolutionary pressure.
Alex O’Connor
The question that’s raised, of course, naturally is why does this faculty evolve in the first place?
David Deutsch
I think there’s only one reasonable answer to this, and that is that it evolved to learn culture. Somebody invented campfires, or each noticeable improvement in campfires was invented by someone, but it wouldn’t have been any use in history if someone had been unable to transmit it to other people. In fact, it seems that it wasn’t just campfires. It was a whole load of things, knowing which foods are poisonous and how to get nutrition out of foods that are hard to get at, which other species don’t have. They don’t have this general purpose facility to do that. It must have been extremely useful, but it depended much more on transmitting knowledge, or I should say receiving knowledge from one’s culture, than on creating knowledge in the first place. Knowledge was created in the first place extremely rarely, but it was passed on all the time. People will have grown up in a culture where their lives, their livelihood, their wellbeing depended on assimilating this cultural knowledge, but they had no writing. Initially, they had only very crude language. By the way, I don’t know what to call him, a paleontologist or language expert called Daniel Everett, who thinks that language evolved long, long before speech did. He thinks even two million years ago, there was language, but it was because language was so important that speech gradually evolved.
Alex O’Connor
That’s fascinating. Okay, so language of some other kind exists beforehand, something analogous to like sign language or communication of some kind.
David Deutsch
Yes, anything symbolic. Some action or behavior that can be taken as symbolic of something else.
Alex O’Connor
That’s fascinating because I think the general picture or assumption is that the evolution of speech and language starts almost in the Wittgensteinian sense of someone sort of pointing at a slab and going, slab, and that evolves into language. But the idea that that language kind of already existed and just needed a vocalization to map onto is a really interesting thought. It does also raise the question, could it have been that we normalized in our evolutionary history on a different trajectory communicating through some other means? Communicating just with our hands, like sign language is the norm or something like that. I suppose vocals are probably the best way of doing it. I can’t imagine a more efficient way of getting information across, but that’s a really interesting way of thinking about it. We’ve got now this potential explanation for why, as you put it, creative explanations evolve in the human psyche, but they lay dormant because what they evolved for was passing on knowledge from society to society, how to start a campfire, this kind of stuff. Then something happened, and I don’t know if you date it to the Enlightenment or if you think that when society started to emerge much earlier than that, something also kind of went on.
David Deutsch
No, no, not that long ago.
Alex O’Connor
At some point something changes, right?
David Deutsch
Yeah, it’s the Scientific Revolution. Perhaps that was the first of the revolutions and there was the Enlightenment. The process of switching to this new kind of thinking has not finished. There are many aspects of our culture that are still of the old type.
Alex O’Connor
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David Deutsch
I don’t think those things changed us cognitively. It’s hard to find the right word because cognitively can apply to things in the brain and also things in culture. So I think what has changed since a hundred thousand years ago or whatever it is, is only culture. The changes in brain and anatomy are relatively trivial by comparison. And I don’t think that the advent of civilization, like four or five thousand years ago changed anything. It changed it only quantitatively. That is, after we had people living together and working together the whole time and trade and that kind of thing, then we needed more sophisticated language. We needed more sophisticated concepts and more sophisticated culture, which led to writing and so on. But I think the real change, the important change, is the change where improvements in culture happen on a timescale that’s noticeable to humans. Before that, it was really just dumb evolution. People may have contributed to it creatively, but then individuals have been creative right back to two million years ago or whatever it was. But people who notice change in society and then contribute to change in society, that is only a few hundred years old. And these landmarks like the scientific revolution, Galileo, and then the Renaissance, those things are quite recent. Though I do speculate in The Beginning of Infinity that it might have happened many times before. So that cultures, as it were, were trying to switch to this new mode but were destroyed for one reason or another. They failed to find a way of being stable under change. That seems to be the really new thing about our enlightenment. That we can have noticeable change all the time. We can complain about it all the time. We can fight against it and so on. But the society retains its coherence. No guarantee this will continue. But yeah, we can hope.
Alex O’Connor
For most of human history, if you asked somebody, what do you think life looks like in a hundred years from now? Like if you had to draw a picture, they would draw a picture of the world today. If you asked somebody a thousand years ago, draw something a hundred years from now, they would maybe say, well, I hope that my son has become a master in my trade or something like this. But there would be no new technology. Maybe if you said, what about a thousand years from now? They might imagine that cities are bigger and stuff like this. But today, if you ask somebody to predict what life might be like in 10 years, they’ll be talking about flying cars or invisibility cloaks or nuclear war or whatever it is. These unfathomable changes that happen in the blink of an eye. Now that to me is the difference. You spell this out quite illustratively, I think, and helpfully in pointing out that if you look at architectural movements, experts in architecture can look at a building from hundreds of years ago and say, it looks like it’s 14th century. They can sort of date it plus or minus a hundred years based on the shape of its windows or whatever. Today, you can look at an iPhone and date to within the year because the changes are happening so quickly. I don’t know if that’s a fair comparison because architecture even today probably doesn’t move quite so quickly. But it’s clear that things are speeding up. Now, to me, before considering what you have to say on this kind of stuff, I look at that and I think this is just the nature of exponential growth. It’s a bit like how the human species is growing in number and for thousands of years, there weren’t that many people in the thousands, millions. Then because of the nature of exponential growth, right now it seems like by the time I die, there might be 9, 10, 11 billion people on the planet. That’s a crazy growth, but that’s nothing special. That’s just because things grow exponentially. We just happen to be at the fastest bit of the exponential growth in technology so far. Isn’t it just that? Why do we have to posit that something significantly changed?
David Deutsch
I don’t think so. There certainly is a factor that the more people there are, the more thinking happens and that’s a good thing. I think that may well have contributed, especially recently. I don’t think it explains the technological takeoff at all in both directions. First of all, if you think back to antiquity, I speculate in the book that what Athens had before it lost the Peloponnesian War was a nascent enlightenment and it failed. Athens was like 10,000 citizens. It may have had 30,000, 50,000 inhabitants, but the people who were contributing to the culture that we now call Athenian culture were maybe 10,000 people. Even at the time, there were, I don’t know, a billion people in the world. The number of people was a factor, but it wasn’t a significant factor. It wasn’t a factor that increased the creative population of Athens by that much. It did a bit because Athens became great because it was a trading nation and so on. There were those factors, but the main thing is that it had a culture of what we would call human rights and democracy and pursuit of truth and freedom and so on. Pericles says in his funeral oration, he points to things that would have been very alien to every other culture at the time. He points to saying things like, well, our educational system is so much more lenient than everyone else’s. Good heavens, everyone else would have said our educational system is so much more harsh and called that a good thing. He says, we don’t care what people do in their own homes. Again, other cultures were conformist. It’s not that it was a perfect culture. Cultures that change are by definition not perfect. They start off worse than they become. Now, if you go over to the present day, the iPhone and so on, those changes are again being brought about by a small minority of people. It’s certainly more than 10,000 like in Athens, but it’s nowhere near the billions. For a start, it’s really only happening in the West. Then within the West, it’s mostly happening in the Anglosphere and so on. I could go on and offend more and more people, but I don’t think the current exponential growth in technology is being population driven.
Alex O’Connor
Well, I don’t mean to suggest just that it’s because of the population getting bigger. I mean that in the same way that populations naturally can exponentially increase, as an analogy, not as a causal explanation. Technology does the same thing. Somebody inventing an iPhone doesn’t have to work from scratch. They’ve got computers, they’ve got computer chips, they’ve got screen technology, and all they have to do is put it together. That’s still quite a big task, but the more that happens, the easier those kinds of inventions and developments become. It makes sense that at some point it gets off the ground and then exponential growth, not because of some shift in mindset, but just because we’ve got more technology to build upon that.
David Deutsch
Yes, but just because something could happen doesn’t mean usually that it does happen. When somebody invented that first campfire I was talking about, you could say, well, it won’t be long before somebody drops some food on it and finds that once it’s been on the fire for a while it tastes better. Yet that didn’t happen for 10,000, 20,000 years.
Alex O’Connor
Interesting, because it takes a kind of mindset of we want to go and find out stuff. We want to go and figure out how can we produce better food? Why is this healthy? Why is this unhealthy? That kind of stuff. That’s the attitude that is embodied in the Enlightenment.
David Deutsch
Exactly. Exactly.
Alex O’Connor
So we’ve mentioned the Enlightenment, and I know that you’re not a fan of defining terms. Neither am I in many respects. People generally have an idea of the Enlightenment as being something to do with the scientific revolution, something to do with some political movements that happen. Roughly speaking, when are we dating the Enlightenment to? What kind of thing are we talking about in a family resemblance style definition?
David Deutsch
I think you just defined it quite well when you said it was the idea that we can improve things, that we can go out into the world and find out how to make things better, that sort of thing. It didn’t happen…
Alex O’Connor
And when does this come about?
David Deutsch
Yeah. Well, Galileo had it, but probably most people in his day did not have it. So most people in his day were not thinking about the world in the way that he was. In fact, they were stigmatizing the way he thought about the world. He had trouble with the Inquisition. And Bronowski said that, and I don’t know whether this is historically accurate or not, but I trust Bronowski, he said that Galileo’s experience put a complete stop to scientific progress in the Mediterranean region. And it was only because progress moved to Northern Europe that what we call the Enlightenment continued if that hadn’t happened.
Alex O’Connor
Sorry, you mean what happened to Galileo put people off?
David Deutsch
Yes, specifically to Galileo.
Alex O’Connor
Yeah. So Galileo’s treatment by the Inquisition was sort of the thing that puts a stop to progress for a time because people see that this is what will happen.
David Deutsch
Yes. One can argue no doubt about what the historical forces were and so on, but it was either that or it was that kind of thing or it was that tendency. There certainly wasn’t the other tendency in society. When it then took shape more in especially the Netherlands and then in England and Scotland, it became more recognizably what you described.
Alex O’Connor
So when does that begin happening and at what point do we consider it? I’m talking on the scale decade here or whatever you like. When does it start to let’s say get off the ground? And also why? Is there something that happens that suddenly snaps people out of this thousands year long slumber into the Enlightenment?
David Deutsch
It seems to have happened because of accidental reasons. When it happened in Florence, it was because previously there had been a fragmentation of polities and the growth of trade. So you’ve got these super rich people. The super rich people somehow got the idea that they made better buildings in antiquity. How come we can’t do that now? So they hired people like Michelangelo and Leonardo and said, can you do this? And they first did it and then they realized they could do it better. And once they realized they could do it better, the Renaissance took off. And then in Northern Europe, again, it was accidental circumstances like the Netherlands were a tiny country fighting the most powerful superpower, namely the Spanish and then the French. And how they survived is a miracle. And this miracle was caused by thinking about how to survive. And they had a society that had Protestants and Catholics and Jews and free thinkers. And they had to find a political setup where all those people could contribute positively rather than fighting against each other. I saw in a documentary once in the reign of Queen Elizabeth. The documentary was about Queen Elizabeth I, but one of the scenes was an ambassador from the Netherlands came and had some negotiation with Queen Elizabeth I. And he was the first commoner ever to have engaged in a negotiation with someone royal in Britain or maybe in Europe. I don’t know. And then in 1688, the Glorious Revolution, that culture, that political culture, but also to some extent the other things, philosophical and so on. But there was mostly political culture got shifted bodily to England and then a few decades later also Scotland needed a rationale that didn’t risk the destructive effects of monarchy. So they…
Alex O’Connor
What is the Glorious Revolution? 1688? But what happened? Can you- …
David Deutsch
Oh, so they kicked out the previous king or they claimed that he abdicated, but in fact, they kicked him out because he was conspiring with the Catholic superpowers. I think in his day, that was Louis XIV or someone, I’m not sure. But anyway, it sounds very anachronistic to say, oh, it was the Catholic danger. But the Catholic danger was like the jihadi danger today or rather, if there was a superpower in the world, if the major superpower in the world were jihadists, then somebody having a jihadist ideology was an existential danger to any kind of progressive society that was trying to form. So then they invited in the- not the king, but they invited in as king a Netherlands noble, William, who then became the King William. And they allowed him to be king on condition that he promised not to do a certain number of things, which the previous king had done to try to restrict the privileges of parliament and individual rights and so on. And that thing that they presented him with to sign was the English Bill of Rights, which was then copied a hundred years later by the Americans to make the American Bill of Rights as somewhat improved version. But it started off in England and that was where the concept of constitutional monarchy began. So he was the king, but for example, the succession could be determined by parliament if they so chose.
Alex O’Connor
And you’re beginning to see the creeping in of, for want of a better word, rationalistic approaches to things like government that had traditionally been the prerogative of these slightly mystical, authoritative, quasi-divine institutions. And the main thing that I think characterises the Enlightenment, for most people at least, is rejection of authority, or at least the legitimacy of questioning authority. So in the scientific world, it’s Galileo against the Catholic Church. In the artistic world, it’s new forms of painting or new forms of sculpture against the traditional way of doing things, although I think that’s a bit less radical, but still there. In political thought, it’s more design, more like upfront design in government rather than traditions that have evolved over time and authorities that are essentially based on those traditions. And this is what the Enlightenment starts to bring about. And interestingly, as you said a moment ago, a lot of this kind of happens by accident, but that’s not a surprise because that’s how evolution works. Like on a biological level, it’s accidental, by which I mean essentially random mutations, that when they happen to hit on something good for whatever reason, evolution just catches onto that and it begins to spread. And similar things happen in the world of ideas. So I was thinking about writing. Like where does writing come from? Well, most people think, most experts as far as I know, believe that it sort of evolves in Mesopotamia and that its first instances are probably economic. They probably invented ways of writing in order to keep their accounts, in order to make sure that the money was going into the right places. And so nobody is inventing writing with a view towards one day, increasing biblical literacy during the Protestant revolution. But obviously writing has had this revolutionary effect on our ability to communicate with each other and share ideas and stuff. And the people who hit upon that hit upon it for a completely different reason, but because it just so happened to be so good at doing this other thing, it stuck around. And it sounds like maybe the enlightenment sort of gets going for a similar accidental reason.
David Deutsch
I think it did. But with hindsight, we can usually see that it wasn’t an accident that this discovery could lead to something else. Not that it would, it need not have. And I think in most cases, it didn’t. But there was a reason why inventing writing later caused the Protestant Reformation. And there was a reason why the Protestant Reformation, which at the time, you might think it was an anti-enlightenment movement. It’s what we would today call fundamentalist religion. But it had in it this rejection of authority. And that was more important than any of its actual doctrines, because that rejection of authority led to other rejections of authority. With hindsight, we can see that. At the time, we probably couldn’t have.
Alex O’Connor
Yes. And that’s one of the big sort of Catholic qualms with Protestants. And I mean, at the time, as well as I suppose now, with a historical lens on, it’s not just the theological disputes, although there is that. There is also this underlying current of like, if you’re able to just waltz in and say that these books aren’t canonical, then how on earth do you know that the books you have in the Bible right now are canonical? And that question, you either ask that question and go, yeah, you’re right. We shouldn’t question that. You’re right. Or you go, yeah, you’re right. We should question that. Let’s find out why these books are canonical. And the Enlightenment spirit is the latter of those. And of course, it’s accidental that people stumble upon writing as an effective means for communication. But it’s no mystery why once that accident has been stumbled upon, it then will of course lead to all of these kinds of wonderful benefits, similar to like the invention of electricity or something. I think when Benjamin Franklin is going around with his key and kite and thinking, this is kind of cool, he probably has some idea that the energy could be harnessed or something, but there’s no way that he has in mind, one day I’ll be able to FaceTime my grandmother from halfway across the globe. But it is easy to see how that naturally comes about because of that. But it means that the shift in mindset of the Enlightenment, I guess we’re painting it here, not so much as a bunch of people getting fed up with living in an authoritarian state and going, we’re going to champion reason and change the world. It’s a slightly more historically accidental movement that just happens to hit upon something good.
David Deutsch
Yes, usually people wanted to solve specific problems, not change the environment for solving problems in general. Usually, I mean, sometimes, they had grandiose ideas.
Alex O’Connor
It’s only recently that we start thinking in those terms. These days, we’re constantly talking about technologies that will improve the world for our children because we’ve developed a mindset where that kind of thing is possible. Whereas it’s hard to emphasize to people now that if you were living in the Middle Ages, there is no like, let’s create a better world for our children. It’s the same world, like nothing changes. There’s nothing new under the sun. Which is a quotation from someone making that very point in the Bible.
David Deutsch
Yes, from Ecclesiastes, that nothing ever changes.
Alex O’Connor
If only the author of Ecclesiastes had access to the iPhone.
David Deutsch
Most of the time, certainly before the Enlightenment, but I think even since, people had in their hands the means of creating the universal something universal, and they didn’t. They failed. Writing was invented, and then alphabetic writing was invented, which made writing many times more efficient and didn’t require professional scribes and so on. It didn’t spread. Similarly, numbers were invented. The placeholder system was invented with the zero and so on, and that didn’t spread. When it did spread from Mesopotamia to India, and then to the Muslim world, and only then to Europe, like basically after the Renaissance. Then it was resisted. The argument that, look, this is much more efficient and easy and so on, that didn’t speak to people because, as you just said, they didn’t have a conception of the world improving, especially improving by a small change whose consequences you can’t predict in advance. That, again, was not just, oh, it’s better, wasn’t an argument. We’ve always done it this way.
Alex O’Connor
So it sounds a little bit to us now when we hear of an old society or a king going, no, no, no, we can’t allow this. It sounds like to us, like, gosh, he’s suppressing progress, but you’ve got to remember the mindset. Today, we have this idea that the world will change radically within the next hundred years, and so our decision is, how is it going to change? We better be engaged in figuring out, of all the possible options, which one we want. In those days, it wasn’t like, well, the world’s going to change in a hundred years. Let’s look for which solution is best. It was like, the world isn’t going to change, and here’s someone coming along, not presenting the best option, but just something new. They’re injecting themselves into a society that is thought of as stable. It’s totally understandable to me why a ruler would look at that and go, whoa, no thanks. We’ve been doing this for hundreds of years, thousands of years, and it works. We can’t have this radical interference. It’s only today with our mindset that change is inevitable, that we’re so much more comfortable with exploring these ideas, I think.
David Deutsch
Yes. This ancient king you’re thinking of would have said, look, I’ve got enough troubles as it is without introducing something new and unpredictable. Yes. I’ve got enough troubles of the old type. Yeah, and there is something that …
Alex O’Connor
Comes along as well with the scientific revolution and afterwards, that people kind of start to care about truth for its own sake. I don’t mean truth of the kind where Jesus is the way, the truth, and the life, but truths of the kind of metaphysical truths, like what is an atom? What is it made of? Why are the planets in orbit outside of divine prerogative? The thing that strikes me is that, as you write about, it’s not like our apish ancestors weren’t looking at the stars at night and also wondering, what are those things? What are they made of? Why are they there? Why aren’t they falling down to the earth? So what is it that has allowed us to start answering those questions more sufficiently? You’ve said that one of the defining characteristics of the Enlightenment, maybe the defining characteristic of the Enlightenment, is not so much rejection of authority or science, whatever that is, but specifically seeking good explanations.
David Deutsch
What does that mean and why is that? I think that encompasses the other kinds of thing, like rejecting authority and so on, because a good explanation is you can’t tell if an explanation is good until you criticize it, until you find out whether it solves the problem it’s intended to solve. You can’t find a good explanation without criticizing it with a view to changing it if it turns out not to meet the criteria that you want. So I define a good explanation as an idea which is hard to change without losing the property that it explains or it purports to explain. But it purports to account for if we want to put it in a non-circular way.
Alex O’Connor
Sure, like how the explanation of why the planets are in orbit is because the angels are holding them up. That’s an explanation, but it’s a bad explanation because you could just change that explanation without really affecting what it essentially predicts. Maybe the angels are pulling instead of pushing or if we then discover that the planets are actually they sometimes crash into each other in other solar systems, we say, well, sometimes the angels go for lunch or we could just literally come up with some explanation as we go along. It needs to be something that is, well, it sounds to me like a good explanation therefore needs to be falsifiable, but I don’t think that’s quite the right word.
David Deutsch
No, because falsifiable where it applies, it only applies in science. So this doesn’t tell you what makes a philosophical explanation, for example, good or bad. And even in science, it really only addresses the predictive part of a theory. And so like we were talking about last time, if somebody has a theory that’s philosophically nonsense and it makes the same predictions, then it can’t be distinguished from another theory. It’s a better explanation. But what will happen is that if somebody or if the scientific culture becomes committed to the bad explanation, then it will prevent further progress because further progress is always at the level of the explanation. Somebody thinks of a new thing that could be happening, a new unseen thing that could account for the seen things. The explanation in science is always accounting for the seen in terms of the unseen.
Alex O’Connor
Yes, and this happens in science, like the idea of authority, you’re kind of imagining the scientist versus the Catholic Church. But I mean, famously, Einstein’s greatest blunder, as he described it himself, his greatest blunder was that his calculations, his equations of relativity, and I’m not a scientist, so forgive me for butchering this, but they essentially predicted a finite universe or an expanding universe. And Einstein was like, well, the universe can’t be expanding because the universe is infinite. And so he adds in this constant, the so-called cosmological constant into his equation in order to square his theory of relativity with the infinite universe. And then- …
David Deutsch
It’s not actually the infinite part that was the problem. The expanding part. Yeah, the expanding and contracting.
Alex O’Connor
Sure. Okay, so- …
David Deutsch
He wanted the universe to- …
Alex O’Connor
To be static. Yes. Yes, so Einstein thinks the universe has to be static for various reasons. It doesn’t make any sense for the universe to be constantly expanding or whatever. It has to be static. And since his calculations said that the universe is expanding, he’s like, oh, well, we need to rectify this problem. So he adds in the cosmological constant to make the universe static again. And then as it begins to emerge experimentally, that the universe is in fact expanding, he removes this cosmological constant and calls it his greatest blunder because he did not add in that constant because he needed to explain some experimental data or because it logically didn’t make sense without it, but because he had an assumption about the way the universe worked and just had to make his theory fit that assumption. Yes. And Einstein did that. This isn’t some fool. This is Einstein.
David Deutsch
Yes, yes. And curiously, one of the main people that made progress in this area was not only a mathematician, but a Catholic priest at the same time. So some things had changed even there.
Alex O’Connor
Yeah, Georges Lemaître, I think his name. Yeah, Lemaître, yes. I’m thinking of the right guy. Yeah. And he- That’s right. Is he the man who- No, he didn’t coin the term Big Bang, but he was one of the first people to sort of be talking about it as a scientific theory. Was it Fred Hoyle?
David Deutsch
Fred Hoyle coined the term disparagingly. Yeah, like on a radio show, he was like…
Alex O’Connor
Oh, this silly Big Bang theory. And fast forward a few hundred years and that will be what he’s mostly remembered for.
David Deutsch
And an even bigger picture, which includes things other than science, it includes philosophy and mathematics and interpersonal relationships and every other application of knowledge to the human condition, it existed from the beginning until now. There’s a conflict between, as I said at the beginning, the faculty of creative explanation evolved not for making creative explanations, but for preserving existing knowledge, preserving existing culture. And ever since then, there has been an inherent conflict in the human condition, both individually and in society, between the need to preserve existing knowledge and the need to create new knowledge. And for most of human history, preserving existing knowledge trumped any kind of attempt to improve knowledge because attempts to improve knowledge risk error, or rather, to be exact, it risks error that has never occurred before. There were plenty of errors that had occurred before. Like I said, plenty of kings got overthrown because they couldn’t solve the problem of how to fend off the enemy. But they were in familiar territory conceptually, and they were afraid of changing culture. And this fear of changing culture was built into culture. And this conflict exists to this day. We have the most extreme example known to me in the West, anyway, is the conflict in education between preserving existing knowledge and creating new knowledge. Even today, education theory is conceived as the theory of how to decant existing knowledge from the brains that already know it to the brains that do not yet know it. And that’s, Popper calls that the bucket theory of the mind, that the mind is a bucket and knowledge is a fluid. And what he stressed and what I always also want to stress is that not only is that a mischaracterization of knowledge and of the use of knowledge, but it is the wrong way around as a practical matter. Even right back two million years ago, the transmission of cultural knowledge was not something done by the transmitter. It was something done by the receiver. The transmitter did things like light a fire and hit the younger person when he didn’t put the branches on straight. You can’t transmit knowledge that way. Knowledge there just isn’t enough bandwidth. To transmit the actual knowledge, the receiver has to guess what each particular action is for. And even if the one’s language had evolved, even if the transmitter of the knowledge actually tells him what it’s for, you have to leave gaps so that the air can get in. That’s not going to mean anything to the receiver unless the receiver can guess the picture that is in the other person’s mind, the picture of the flame being nourished by air coming in and the air being able to rush in through the holes and so on. If you try to explain something without a purpose to somebody, you’ll see that they don’t get in mind the same picture you do.
David Deutsch
It’s only when they’ve understood what you’re trying to say, then they can be accurate. And even then, even with modern language and culture so tightly knit, again, I put this example into the book. If you tell somebody directions, like first left, second right, they want to find the nearest garage and say first left, second right, then turn right again at the church or something, usually that won’t work. Usually, there’s enough leeway in the concept of first left and second right and at the church to mean that there’s too much chance of them getting lost until they understand what you’re saying, that you’re trying to tell them how to avoid the part of town that has the side streets and you want to get onto the part of town that has the main road. Once they’ve understood that you’re trying to tell them that, then they can understand the first left, second right bit.
Alex O’Connor
Yeah, so we’re now talking about, to be clear, the way that people learn things and the way that education works. And there is this idea, as Popper calls it, the bucket theory of the mind where the transmitter just says stuff. I say, Professor Deutsch, here is how you make a fire. And you go, thanks, Alex. And you’ve learned something. Whereas the idea that Popper has and that you have is that’s not how it works. Instead, you have to take a guess yourself. You have to just conjure up a guess as to how something works and then sort of, I guess, like test it against reality.
David Deutsch
Exactly, test it, criticise it.
Alex O’Connor
And the immediate thought I had with the fire thing is that now that we have language, if I explain to you how a fire works, now, of course, you’ll already have had to sort of learn language and know what wood is and stuff, but suppose that’s the world we’re in now. Like you and me, imagine that I just didn’t know how to make a fire, which, to be honest, if you stuck me in a forest with no, like, anything, maybe I wouldn’t know how to start a fire, to be honest. Something to do with flint. Or there’s something, it’s like you put a bit of string on a stick and then you sort of rub it back and forth, something like that, right? So I don’t know. So someone’s going to come along and they’re going to say, well, actually, Alex, what you need to do is take some tinder and put it on the floor and then get a bit of flint and this kind of thing. And they sort of show me how to do it. The feeling I get is that they have just told me something. I’ve learned because I’m a big bucket. They’ve taken that information. They’ve put it into my mind.
David Deutsch
Where am I going wrong there? The wrong theory of epistemology is quite intuitive. It’s, there’s lots of facts about knowledge that are not intuitive because most of what is happening is happening unconsciously. What’s happening in your mind is happening unconsciously. If you think, especially if you think that it must be the case, after all, first he knew it and I didn’t, and then at the end I knew it and he still knew it. So something has been transferred, but not by the mechanical means. It is transferred by means that absolutely depend on what the receiver does and what the receiver wants. So you can be, many people have been taught how to make fire and can’t make one. And on the other hand, many people have learned how to make fire just by watching somebody making it. The historic chess grandmaster, Capablanca, learned how to play chess at the age of four, just by watching, never having been told the moves. And the first that his father knew about it was when he told his father he’d made an illegal move. So he learned, he wanted to learn and he was forming conceptions and theories in his mind about what this, why these people were sitting at that board with bits of wood and moving them around and taking it so seriously. He got that idea in his mind that this was interesting and he thought about it and his first series will certainly have been wrong. But he criticized them by further watching. And if they had told him, that would have played exactly the same role. If he had been told some of the rules, then again, he would have tested his existing conception of what the rules were against what they were saying. And sometimes they would have been saying something ambiguous and he would have had to resolve the ambiguity by testing his theory against like, what were they trying to say? Oh, they were trying to say you do that when you have moved your pawns. Okay. You can’t move the rook until you move your pawn. That’s what they mean. Or you might have an idea that’s wrong. And again, you test it against what they’re saying. And that is the role of the other person.
Alex O’Connor
So then just forgive me if this is naive, but suppose somebody just burst into this room right now, came up to me and said that, I don’t know, the definition of a bachelor is someone who’s unmarried and then they left. And suppose I didn’t know what a bachelor was before that. And okay, I now, I suppose you also have to assume that the person who burst in is someone knowledgeable. Let’s say that it’s my friend in the next room who’s writing a dictionary. They’re a lexicographer and they sort of burst into the room and they go, Alex, a bachelor is a word, meaning someone who’s unmarried. And then they leave the room. I feel like I’ve just learned something. Like I’ve just been educated in some respect. I don’t feel like I’ve brought really anything to the table there. I feel like someone has just like placed that into the bucket and now I know it. But how would you characterize that specific instance of learning in a way that …
David Deutsch
Indicates my role as the learner? So you’ve chosen a situation in which both of you have a huge amount of shared knowledge to begin with. You know that he’s a lexicographer and he’s trying to investigate the meaning of words and so on. Then he rushes in. I don’t know why he thinks you don’t know what a bachelor is, but perhaps you happen to not know. And he tells you it’s someone who’s unmarried. That’s wrong. It’s a man who’s unmarried. So you will then criticize that theory that you think he told you. He thought that he was telling you only about the unmarried part and you already knew about the man part. Perhaps because of the previous context or even a previous conversation, you had been wondering about the exact meaning of bachelor. And now he comes in and he tells you from his point of view, he’s telling you the thing that we were both missing before. But you hearing it think that he’s telling you the full definition and he wasn’t. And those things were not stated. They were guessed. Both of you guessed something and it so happens you guessed incompatible things, only one of which was right. But a more realistic scene would have you both being wrong initially because it would usually continue along the lines of, are you saying that so and so? And then he would say, no, no, I’m actually saying so and so. And then you would say, ah, I see, you’re trying to solve the problem of this. And he’d be saying, yeah, and so on. So there’d be a two and three.
Alex O’Connor
Yeah, like, oh, there’s a great irony in the fact that I actually just mistook the definition in my example. You know, oh, a bachelor is someone who’s unmarried. Oh, really? So like my sister’s a bachelor. Oh, no, no, no, it’s only men who are unmarried. It’s like, oh, you know, my granddad died a couple of years ago. So he must be a bachelor now because he’s dead. So he’s not married. No, that’s not quite what I mean either. And like the only reason why you escape those kinds of conversations is because you’ve already taken a guess at the fact that he’s not referring to dead people and that when he says men, he means living men and he means…
David Deutsch
Yes, fully grown men as well.
Alex O’Connor
Yeah, right, quite. And so there are assumptions that one brings to the table, I suppose, is what we’re talking about here. And what we’re talking about here as well is me and the way that I develop beliefs, right? Education, again, naively, is the means through which knowledge is passed on from one person to another. We’ve just demonstrated the fact that a lot of the time in this transmission of knowledge, there are mistakes, there is guesswork, there’s all kinds of stuff going on. So without trying to sound too sort of pseudo profound, what is knowledge? Like I’ve talked about it before, famously, philosophers have tried to define knowledge and found it very, very difficult. And I’m not necessarily looking for a precise definition, but suppose I have a belief, I believe that it’s raining outside and suppose that tomorrow I know that it’s raining outside. What is the difference between those two mental states?
David Deutsch
Yes, well, incidentally, and we can come back to this, I don’t think there really is such a thing as belief or if there is, then it’s a very irrational state. But to answer your question, first of all, knowledge is a type of information. It’s a subset of information and it’s specifically the kind of information that can have a causal effect. So I can buy a lottery ticket with a serial number on it and then I can tell you the serial number. And so I’ve passed on a bit of information that doesn’t have a causal effect in itself because it could have been any other number I told you and it would have no different effect on you than that other number. It’s only relevant if it’s going to have an effect on somebody like the people running the lottery. If it has an effect on them, then I can tell you. But then it’s not enough that I tell you the number. I have to tell you this is the winning number of a lottery and the lottery in question is the British National Lottery. And you better cash it in before this evening because that’s the deadline. Otherwise, again, it doesn’t have the power to have an effect. And this power of knowledge to have an effect is if we take an even bigger perspective than going back two million years to early humans, if we go back to the context that there is life on earth and not anywhere else that we can see, there may well be life where we can’t see it, then there is something fundamentally different about the information on earth from anywhere else because the information on earth can have a huge effect on physical processes. So somebody can have an idea and this idea can deflect an asteroid that’s heading towards the earth and thus prevent a mass extinction. And again, whenever it was 800 million years ago when blue-green algae evolved the knowledge, this is a Popperian conception of knowledge which includes knowledge that isn’t known to a person, but is nevertheless information that has a causal effect. The evolution discovered a way of harnessing sunlight to make energy and it had the side effect of creating oxygen. And as a result, the blue-green algae, that one gene which began as a mutation in one precursor of blue-green algae, then spread as they multiplied and then they made more oxygen and the amount of oxygen they made exceeds by a factor of 10 to the 40 the mass of that mutated gene. So nothing like that happens anywhere else other than the earth. Everywhere other than the earth, the big massive thing affects the small non-massive thing, period. The small thing doesn’t affect the big thing, barely affects it, doesn’t noticeably affect it. So a comet hits the sun, the comet is destroyed, the sun is basically going to carry on doing what it was going to do anyway. On the surface of the earth, I call that the hierarchy rule.
David Deutsch
The hierarchy rule holds wherever there isn’t knowledge. Where there is knowledge, the hierarchy rule is reversed. We’ve only just begun on this journey of reversing the hierarchy rule and we’ve only done it slightly on earth. So when we’ve done it by a factor of 10 to the 40, we’ll be commanding the galaxy.
Alex O’Connor
So could you approximate a definition of knowledge? When you say the word knowledge, what roughly are you talking about or are you quite allergic to definitions?
David Deutsch
I’m somewhat allergic. I wouldn’t want to use what I just said as a definition. It should be the other way around. There is this thing that reverses causality and so on. Let’s give it a name. You can call it Fred if you like. Right, okay. It’s a label. Yeah, it’s a label. But then there’s also the concept of knowledge as it has existed in philosophy where there you’ve got to distinguish between perverse, downright wrong conceptions of knowledge and conceptions of knowledge which are closely related to this ability to reverse the direction of causality. So if knowledge is, again, I’m quoting Popper all the time, but what can you do? For thousands of years, philosophers thought that or defined, some people have disputed that as well. But at any rate, they thought of knowledge as being a justified and true belief. So you just said, what’s the difference between when I just thought it was true and then I knew it was true? The traditional answer has been because it has attained some justification. You’ve proved it or you’ve observed it by personal experience or somebody has told you whom you trust and that kind of thing. That’s just wrong. Nothing is ever justified in that sense. Nothing is even ever true in that sense because we’re always improving our knowledge like with the bachelor. We can improve it again and then one day the concept will be useless and everybody will forget what a bachelor is just as they have now forgotten what a farrier is. It has to do with the horseshoes. Oh, right. Okay. Yeah. Fair enough. I’ve got no reason for that. But then, in the Enlightenment…
Alex O’Connor
Spirit, I do like knowledge for its own sake, so I’ll go and look that up. This idea of justified, true belief, as you say, it’s for a long time the definition of knowledge because I could believe that it’s raining outside with no justification or with a bad justification like a witch told me that it was going to rain today. If it just happens to be true that it’s raining outside, lucky me, but it still doesn’t feel like I know that it’s raining. So it has to be a belief I hold which is both true and also justified because if it’s justified and false, it’s not knowledge either. Then you get Edmund Gettier coming in and I’ve spoken, if people are interested in the theory of knowledge, I’ve got a video on my channel. I think it’s called something like how one man changed philosophy by accident or something like that because he goes to publish this two page long paper that undermines justified, true belief. But the big problem for me in this whole discussion is this difference between belief and knowledge. Like you say, something can be seemingly true but then not true. Until Einstein came along, we were all operating on a Newtonian understanding of the laws of physics. So we knew things like objects of bigger mass will attract other objects with a bigger force of gravity and we knew that that was true, that we knew that that was the case. When Einstein gives us a different picture of what gravity is and how it works, it still remains true that objects of a bigger mass exert more of a force. But I’m like, does that mean that we actually didn’t know that before? Because although it’s like the same conclusion, it was sort of based on totally different premises. It kind of seems to me like we still knew it, but maybe it’s more right to say that we didn’t. And as soon as I start asking questions like that, the concept of what knowledge even is just kind of falls apart. I’m like, I kind of firstly don’t really care. And …
David Deutsch
Secondly, I don’t know how I would even possibly define it. So first of all, defining knowledge as being truth is doomed from the beginning because we never have truth in that sense. But what do you mean by that when you said that a moment ago? We never have truth. Well, we can have, when we have a theory like a bachelor is an unmarried person, that contains truth. That is, it has useful consequences that might be the only consequences you need for your particular application. But it’s not true. And like Bertrand Russell and Whitehead spent 300 pages or whatever it was proving that one plus one is two. And then it was realized that you can’t define things by axioms anyway, because there’s no such thing as proving that an axiom system is consistent. Yes. So this search for justified truth, even in pure mathematics where you might think that true, there’s unambiguous truth about numbers two and one and equals and plus and so on. But it’s not true. That whole system is just a conjecture. Okay. So to be clear, when you say we can’t have …
Alex O’Connor
Truth, you’re not implying that there is no truth and truth or falsity. You mean literally that we can’t have it. It’s there. It’s just that we can never have it because we’ll only have something like half truth. So for example, if I said to somebody, every homo sapiens, every human being under the age of six is an ape. That’s true. Yes. But it’s like, there’s something missing from that picture. It’s kind of misleading. It’s going to lead us into all sorts of trouble if I’m not more clear. And so, okay, what I mean to say is that every human being is an ape, but then that itself will rely on understandings of what like taxonomy is and categories. And if you really want to get the fullness of truth in every possible respect that could even possibly be relevant to that statement, you’d probably basically require like infinite knowledge, right? Because you would need to understand how language works. You’d need to understand taxonomy. You’d need to understand like the philosophy of taxonomy. You’d need to understand whether objects can exist. You’d need to study mereology in parts. And you’d need to know all of this. The only reason that we don’t on a practical level need that is because on a practical level, we only ever go so deep.
David Deutsch
We only ever go as deep as is needed to solve the problem that we’re currently solving.
Alex O’Connor
I see. I see. And so, knowledge becomes relatively practical because if you can’t have knowledge in the sense that the philosophers define it, then when people are talking about things that they know, they’re getting at something slightly different, which is like a practical…
David Deutsch
Certainty or a practical confidence. Well, practical is the wrong word because it need not have any practical application as in vacuuming your carpet. It might be an issue of pure mathematics that only you are interested in, and yet it’s still knowledge. What we are seeking is knowledge, but it’s not truth. Yes. We can find knowledge in the sense that we can correct existing knowledge by removing errors. So, and that’s what the growth of knowledge always is. It’s always removing errors. When I realize what you meant by first left and second right, it’s by removing the misconception that I had before. It’s not that what you told me is false or that the idea that I had is entirely false through and through. It contained truth. Both of them contained truth. Both of them contained error. To get to my destination, it’s enough if I remove errors to the extent that they are relevant to the problem as I want to solve.
Alex O’Connor
Is there anything that you know is true, like in the Cartesian sense of, I think, therefore I am, and maybe that’s all I can know with certainty? Is there anything that comes to mind that you could say I know?
David Deutsch
No. I can think of things that are more certain than that, which are still not certain. There is no such thing as certain truth. Descartes was already assuming that such a thing as I exists, and yet these experiments with memory, first of all, memory is in any case consists of confabulation. So, when we remember something, what we’re really doing is conjecturing what happened using the structures in our brain as clues to test our conjectures against. This process is fallible. In particular, the statement, I think, is extremely fallible because there are now experiments you can do to show that people have false memories of having thought something that they couldn’t possibly have thought because they didn’t know the thing they were thinking about at the time.
Alex O’Connor
That sounds like a minefield. Again, I do actually have a video on Descartes, I think, therefore I am, which is, I think, a more complicated phrase than people give it credit for. There are different interpretations of, you know, is Descartes doing like a syllogism? I think, premise, therefore, conclusion, I exist. Or is it like a singular intuition of the mind? That’s a relevant question here. I discussed that in that video. What I’m really interested in, because my ears are still perked from this, you told me that you don’t…
David Deutsch
Believe in belief. Yeah. There are states of mind that can be called belief. I think irrational ones like somebody who believes in some religion or something. What they mean is that they have a resistance and they are hoping it’s a complete resistance to changing a certain idea. When we’re talking about belief in the world, so first of all, in Popper’s conception, rational thought consists of conjecture and criticism. Just alternating those, like in evolution, we have mutation and selection. So in rational thought, we have conjecture and criticism. The first thing to notice is that belief is neither of those. So Popper has this PC quotation. I see if I can remember it. Belief is never rational. The suspension of belief is rational. In order to create knowledge about something, you’ve got to stop believing at least something. But it doesn’t help to believe anything. You can have a theory, an idea, and you can not know any criticisms of it. I don’t know any criticisms of the idea that the street outside my house still exists. If I’m going to base any action on that, on the fact that I don’t have evidence of that yet, then there’s an infinity of other things that I could act on. Many of them will be the opposite action to that action. But I have a conjecture that exists, and I don’t have a good explanation that can count as a criticism of it. When I don’t have a criticism of something and it is a good explanation, then the rational thing to do is not to contradict it. I only contradict it if I have a good explanation of why it might not be true, or rather why it might not be knowledge, why it might contain an error. So belief is unhelpful in this context because it views the… You know, people sometimes say that some branches of science have physics envy, and then some branches of philosophy have science envy. I think that the belief in belief may have originated in ancient times as a sort of logic envy because it was once, at least when Aristotle formalized logic, but probably even before that, people saw this deduction going on. You could have a definition of prime numbers, and then you could prove something you didn’t know before just by applying this method, deduction. So you start with the thing that you know, you apply a method, and you end up with a thing you didn’t know, and it’s just as secure as the thing you started with. Of course it isn’t, because the axioms could be wrong. You might think the axioms are self-evident, but they’re not. And the thing that people held up…
Alex O’Connor
Could those axioms be wrong? I mean, like, take 2 plus 2 being 4. I mean, it seems like the word equals there, or that the equal symbol is functioning as an indication of tautology. It’s sort of like saying, you know, P equals P, or like, you know, my iPhone equals my iPhone. So I consider something like 2 plus 2 equals 4 to be essentially a tautology of that kind. Do you think that my iPhone is my iPhone is something that can be known, or is that an axiom that might be wrong? And if it is, doesn’t that have some, like, radical implications for …
David Deutsch
The way that we rely on logic for thinking? Not really. It’s just that you’re focusing on a particular use case in which you can’t think of a way in which it couldn’t be true in that use case. But if you have a 6-year-old relative who has just gone into primary school, first grade, or whatever they call it, and they were given the problem sheet—horrific use of the word problem, by the way—problem sheet on which it says 1 plus 1 equals, and in a box where you’re supposed to write the answer, and your young friend wrote in the box 1 plus 1, and it was marked wrong, and you said that’s not the answer they wanted, right? And he says, but it’s a tautology. How can it be wrong? So yeah.
Alex O’Connor
That’s interesting. But then I think that the student would just be—although, of course, in that context, you know what they’re getting at. The teacher, if they were being correct, if they weren’t making a mistake, they would have to say, yes, that is correct, but I’d like to see it expressed in a different way. If the kid wrote 1 plus 1 equals and then wrote in the box 4 divided by 2, the teacher might be kind of impressed and be like, whoa, hey, here’s an extra point. But to say that it’s the wrong answer could only refer to the context. It can’t refer to the …
David Deutsch
The actual truth of the answer itself. So this issue of the context just repeats the same problem. You can never express with perfect precision what the context is. The chances are that any child who gets that question wrong is getting it wrong because they have the wrong context in mind. Mm-hmm. I would guess that it’s very rare to get that wrong because you actually don’t know what 1 plus 1 is in the sense of knowing what the teacher means by asking you what 1 plus 1 is and also not knowing what 1 plus 1 actually is. Yeah. So that combination must be quite rare. Sure. So usually, getting something wrong in that sense is either not understanding the thing, in other words, having a misconception about the thing, or having a misconception about the problem situation that you have been put in. And so it’s the same issue as before. You’ll never define bachelor perfectly. You’ll never define plus perfectly or equals, as Russell and Whitehead will tell you, or rather they would now. They thought they could do it, and it took them 300 pages.
Alex O’Connor
In a way, I hadn’t considered the assumption I bring to the word equals because, well, 1 plus 1 equals 2. Well, does it? Because those aren’t the same thing. Exactly. They represent, I guess, the same idea, but they’re not actually the same thing in the sense of how they’re expressed. Exactly. Yeah, I mean, 1 plus 1 is the same as 1 plus 1. It’s got the same value as 2, but it’s not the same thing. It’s not the same expression. It’s not got the same label on it. It’s not got the same number of pen strokes. So you need to understand the context in which you mean…
David Deutsch
Is the same as in order to answer that question. Yes. And even that can’t be defined perfectly.
Alex O’Connor
Yes. Interesting. Okay. I want to change gears. I don’t often do sort of janky segues, but we were talking before about kind of science, and there’s somewhere we didn’t take the conversation, which our discourse on knowledge interestingly shelved. I really wanted to speak to you about this today. This is the main thing I wanted to ask you about, which is that reading The Beginning of Infinity, there’s this idea that pervades. If you ask somebody, what is science? What does science do? I think the most common answer for someone who knows a thing or two about science is to say, well, what science does is it makes predictions. That’s how we know if scientific theories are accurate. That’s their purpose is in order to make predictions about the future. Einstein proved general relativity by making a prediction about the eclipse and it coming true. And so that’s what science really does. You disparage this idea. You …
David Deutsch
Say that science cannot be about prediction. Yes. Why not? It can’t be only about prediction, but prediction is one of the characteristic methods of science. To be exact, testing theories by testing their predictions is one of the characteristic methods of science. But it is not the purpose of science, partly because as we said last time, you can have two theories that make the same predictions, but one of them is a cope, as you put it, by the way, I’ve enjoyed using that. The Copenhagen interpretation. Yeah. And the trouble with that is not that it makes wrong predictions, is that it stultifies and freezes progress in physics in this case, but in science generally. Science is about explaining the world. It’s about knowing what is there behind the appearances. So we know that the sun rises in the morning and sets in the evening. Originally, we didn’t know why, but we knew that that happened. And as we found out what happened, we realized that it wasn’t even true that it rises in the morning and sets in the evening. It’s that the world isn’t at rest, that the earth isn’t at rest beneath our feet. That’s an astounding way of explaining the observed in terms of the unobserved, the perceived things according to imperceptible things. That’s how science makes progress. The progress in science is progress in understanding how the world is, not in what predictions we’ll make. And my other example that I use is about conjuring tricks. If you go to a Penn and Teller show and you see them doing a trick and they’re going to saw through a lady, and then you can predict that the appearances, the appearance will be that they saw through the lady. But you know that that can’t be the underlying reality, but you absolutely can’t think of how it could possibly not be because they have apparently refuted all your conjectures as to how they created the illusion. So then you’re in a state of perplexity. And this is the state in which scientists are in regard to the world. They are captivated by perplexity that they do not know what is causing the appearances behind the scenes.
Alex O’Connor
Yes, like what is causing matter to hold together, what is causing the Sun to rise, quote unquote. These are the appearances and the scientist is engaged in the undiscovered qualities that are making that happen, the explanation for it.
David Deutsch
And typically we do not observe that underlying mechanism. Nobody has ever seen the inside of the Sun, but we know that it’s there in reality. It’s not a reality. Maybe this is a reality that no one will ever experience, but we know that it’s there and that is in our worldview as a thing that’s as real as what we see the Sun doing in the morning because they’re inextricable. There’s an explanation of the one from the other that is so good that it can’t be replaced by anything that we can think of.
Alex O’Connor
Now, my problem with this or the reason why I can’t get on board with this is because I’ve developed a view of what science is and what science does that is more in line with this other view, which typically is called instrumentalism. What science does is essentially make predictions and describe things, but doesn’t actually explain anything. The reason I think that, for an example, is when Isaac Newton discovers gravity. We’ve known that objects fall as long as we’ve been alive, but no one’s known why that’s the case. Then Isaac Newton comes along and scientifically explains gravity. He realizes that the same thing causing me to fall to the ground on Earth is the same thing that keeps the Moon in orbit around…
David Deutsch
The Earth itself. I don’t think the first thing you said is true, but the second, yes, he unified celestial mechanics and terrestrial mechanics, but he didn’t explain what gravity was.
Alex O’Connor
So this is where I’m going. This is the picture people have of like Newton comes along and he explains gravity because gravity is an inverse square law and objects attract each other across a distance. There we have it. That’s science and we’ve got this theory of gravitation. I have a quote from Isaac Newton actually, and I think it’s relatively well known, but he writes this in the General Scholium to the Principia Mathematica. After explaining and describing how gravity works, all of the mathematical theorems and stuff, he says, I have not yet been able to discover the cause of these properties of gravity from phenomena. As he puts it in Latin, hypotheses non fingo, I feign no hypothesis. It is enough that gravity does really exist and acts according to the laws which we have explained and is sufficient to explain all the motions of the celestial bodies. So Newton just forthrightly admits that he has explained the laws, as he puts it, which are the mathematical properties by which gravity abides, but says, if you ask me what gravity actually is, why gravity exists, why these mathematical laws are doing what they’re doing, I feign no hypothesis. I’ve got no bloody clue in modern English. Now, when I look at what science sort of does and at root, it’s so-called explanations of phenomena, I’m seeing a lot of what looks to me like this Newtonian description rather than an actual explanation. That is a view known as instrumentalism broadly of what science actually is. Are there any sort of obvious counter examples that can just prove to me once and for all right now that I’m wrong about that?
David Deutsch
Well, proof is not available in philosophy, unfortunately. But I think, as you guessed, I’m very much opposed to instrumentalism and I don’t think it’s true as a philosophical theory. I think that Newton didn’t know about Popper. The kind of theory of knowledge that Newton was applying and which he uncritically assumed must be true retrospectively of what he has been doing was just false. He was false about himself just as the people who in these experiments with the brain stimulation think they remember themselves thinking a certain thing which they couldn’t possibly have thought. Newton, having only inductivism as his philosophy of knowledge, thought that he had applied inductivism and therefore thought that he had done nothing more than make a better predictive theory. But it’s not true. You said yourself, and I agree, at least I think it’s the main thing he did, he unified celestial and terrestrial mechanics. That is an explanatory theory. It’s not just a predictive theory. You could have a theory of celestial mechanics and a theory of terrestrial mechanics and never realized that they’re the same because they might be expressed in different terminologies. They weren’t in the case of Newton.
Alex O’Connor
But to be clear, when you say celestial and terrestrial mechanics, you’re talking about the way that objects fall to the ground and fly through the air on earth versus the way that objects do it in space like planets and stars and stuff.
David Deutsch
Yes. That is explanatory because it adds something to the predictions. Somebody could have two theories and then unifying them is a form of explanation. Now, we can also see even better what an explanation is in the case of gravity because, oh, another thing I should add, Newton had to postulate some invisible things, which was explanatory. He had to postulate that there were forces, invisible forces, that act on matter and which were caused by other matter. Again, that was not part of the equations. That was part of the words that went with the equations: that there are invisible forces. Yes.
Alex O’Connor
I’ve always found that word force to be incredibly comic, a bit funny because when we look at how the ancients thought that, oh, Aristotle thought that objects just longed to be with the earth. How silly, how ridiculous, these ideas of mythical spirituality and the gods pushing stuff. No, no. Today, with our modern science, we’ve updated it and we’ve got forces. Yeah, that explains forces. We’ve gotten so used to the idea of scientific forces as a term that it sounds normal. But if you think about what that means, it’s spooky and mystical. Forces, that explains everything. But to me, that’s just as …
David Deutsch
Much of a mythical guesswork as anything else. It’s not the same as the angel theory because the angel theory can’t be tested. The forces theory, although it’s wrong, but it’s got a lot more knowledge in it than the angel theory had because it makes testable predictions. But not only. It also unifies our conceptions which before that, we conceptualized the space outside the earth differently from the space on the surface of the earth. Newton, with this notion of force which exists both on the surface of the earth and in the sky according to his theory, that unified them. Again, this is what characterizes a scientific explanation. Not all explanation, but a scientific explanation. It explains the seen in terms of the unseen. The unseen were the forces and the seen were the planets and the apples falling. Then, when Einstein came along, he first of all said there are no forces associated with gravity. That’s stunningly counterintuitive, but it’s got nothing to do with what anyone observes. Instead, it has to do with his theory that space and time form a unified fabric which is itself dynamic. No one has ever seen space-time. No one has ever seen it curving. This is all part of the unseen part of the theory of relativity which explains the seen part 1% more accurately than Newton did. But that’s not what it’s for. What it’s for is understanding the world. By the way, I shouldn’t downplay Einstein because when it comes to things like the big bang and black holes and gravitational waves and so on, it’s more than 1% better. It’s revolutionarily better.
Alex O’Connor
Yeah, and satellite technology and all of this kind of stuff.
David Deutsch
Yes, GPS, which depends on why you have to include relativity in GPS because it won’t give the right answer. But why won’t you give it the right answer? Because there are no gravitational forces. I say this even to physicists sometimes. They say, well, there are gravitational fields. That doesn’t mean anything. You can’t say something approximately exists.
Alex O’Connor
That’s one of the things that I like about this Einsteinian shift. It’s the most common example given in any context of humans changing their mind. Newton was wrong and Einstein got it right. The most interesting thing to me is Newton’s big problem is I’ve got this mathematical system that describes the motion of the planets, but I’ve just got no idea what it is. There’s some force and I don’t know what it is. I don’t know where it comes from. Einstein, instead of answering the question of where it came from, just says, wrong question. There is no such thing. But that’s why I’m like, is it a better… When you say that Newton unified terrestrial and celestial mechanics, and you say, well, he realized that the same mathematics apply to… But not just the same mathematics.
David Deutsch
Right. Because I was trying to get at the… The same invisible things cause both effects.
Alex O’Connor
Suppose Newton didn’t come up with the word forces. Suppose Newton just realized, the only thing he realized is that the same mathematics that describes celestial mechanics also describes terrestrial mechanics. Suppose that’s all he did. And somebody said, well, why is that? And he’s like, I don’t know. And they’re like, do you think there’s some kind of force? He’s like, I don’t know. All I know is that the same mathematics describes it. And that’s all that he’d realized without positing this false idea of forces. Would he still have been doing science? Because in that case, it seems like he really was just describing something.
David Deutsch
Well, whether he was doing science depends more on what he was aspiring to do. Even if he had failed to find a better law of motion of planets or whatever, he would still have been doing science because he would have been trying to explain the world. He would have been trying to find an explanation of the motion of planets and so on. Hypothetically, he really was just trying to …
Alex O’Connor
Describe it. That’s all he was trying to do. Would that just mean that he wasn’t doing science anymore?
David Deutsch
I think yes. In that case, one could argue that he would never have succeeded because how would he be any different from Descartes? Also, Descartes was trying to explain the same thing using vortices. Okay, forget about the vortices. Just try to explain the planets. Well, okay, he could give you a big thick tome of planetary observations and say, that’s my theory. Okay, it’s perfectly accurate. It explains everything that’s ever been observed, but it’s not a theory. That’s not what Descartes was trying to do. He was trying to explain the seen in terms of the unseen, and so was Newton. They could have both arrived at the same equations, but this is like saying that it’s a good idea to break your leg because after you broke your leg, you went to hospital and you fell in love with the woman of your dreams in the hospital and so on. Therefore, breaking your leg is a good thing. It’s not common to find a thing you’re not looking for. It’s even less common to find a thing without looking for any improvement. You might be looking for one improvement and find another. That’s the thing that sometimes happens like with penicillin. But when you’re not looking for improvement, then you’re like those prehistoric people who had a campfire and did sometimes drop their food into it, but they didn’t think that this could be a better way of life: we could cook things. Wow, just that idea. They didn’t know why food tastes better, but they could imagine a better way of life than the one they had. They could imagine this invisible thing that made food taste better, improving their life and improving what they then observed.
Alex O’Connor
So I have this, like in trying to encapsulate how I feel about science and particularly the issue of science like explaining everything one day and explaining the origin of the universe and stuff like this. My listeners will be sick of hearing it because I bring it up all the time, but I think it’s relevant to bring up again here because we’re talking about the very thing that the analogy encapsulates. When I say it to like a Christian, they tend to really, really like it and think it’s cool. When I say it to a scientist, they’re a bit more suspicious. So I think I can now predict how you would answer to it, but to put it in a more concrete term, right? So I often talk about discovering out in the wild a book of Shakespearean sonnets. I’m imagining somebody who says, look, science will one day explain the origin of the universe and one day we’ll have a theory of everything. One day science will explain all of the, or not all of the questions because there will always be questions, but it will answer lots of the big questions we have right now, at least in principle. Yes. And I’m imagining discovering this book of Shakespearean sonnets on the floor, not knowing what it is or where it came from and being like, I wonder what this thing is. And we look at it and some clever clogs starts poring through it and they notice that at the end of every single sentence or line or whatever, there’s a bigger version of the same letter, the capital letter, and they discover this thing, which they call the law of capitalization. For some reason, there’s this law that every new sentence has a big version of the letter. Then they discover the laws of punctuation. Then they might get really clever and discover the law of iambic pentameter, the rhythm that the words have. And they realize that there’s a rhythm to it and that this is the law of iambic pentameter. And someone comes along and says, why is that law that way? And they’re like, we’re not really sure, but we’re working on it. And then somebody says, look, I’ve got all of these laws of literacy that I’ve discovered. And somebody says, where did the book come from then? And the experimenter goes, well, I don’t know yet, but look at all the progress that we’ve made with these literary laws. I’m sure one day we’ll be able to explain the origin of the book. That would be a category error. And the reason that I use that analogy is because it’s obvious in that instance that what the laws of literacy are really doing there are just describing things we observe. They’re not actually really explaining any of it. They’re just describing it. And so the analogy is that this is kind of what scientists do with the law of gravity and the law of electromagnetism or whatever. Forgive my ignorance here. As I say, when I say that to a Christian, they’re like, wow, that’s a really good way of putting it.
Alex O’Connor
I’m pretty convinced you’re not going to be quite so impressed by that analogy. And I’m interested in why that’s the case.
David Deutsch
Well, for a start, I think you’re unnecessarily disparaging these people. All knowledge begins with myth, dogma. Science begins with unscientific things. Before these prehistoric people wondered what raises the sun into the sky, they first had to think that something does or that the sun does rise in the morning and set in the evening. That is something they didn’t know when they were born. They learned that at some point or to be exact, they guessed it at some point. And only then did they begin to try to explain it in terms of angels and so on. Now, this regularity of the sun crossing the earth is in itself, it is nothing. It’s not science. It doesn’t explain anything. It doesn’t tell you anything about the sun or the earth or anything. It’s proto-science. Wondering about those things and then caring about whether the explanation is actually true or whether it really does correct errors in your previous conception, that’s how science begins. And then only after that do you form ideas that actually meet that criterion of being better explanations than before. So, you then wonder how far away is the sun? How big is it really? And you can’t ask that question until you know about measuring things. So, to take it to your analogy about the Shakespeare sonnets, the first thing that’s unfair is that you’re unfairly disparaging these people who are doing the right thing in this strange universe in which you can just find a book of sonnets and be mystified by how such a thing could possibly exist. But in that strange world, they are doing the right thing and if they keep trying, they will get to more things because they will find more regularities that they will eventually learn to decipher. I assume these people are French or something. They can’t speak English. Yeah, I suppose maybe. Or maybe they’re time travelers from a time before writing or something. Yeah, something like that. All they’re seeing is the printing and the full stops and that kind of thing. But one of them might guess that these things have a meaning, that they were not put there by evolution, they were put there by creative thought. And then they might decipher what it means. And then they might see that there are similarities in the meaning of different sonnets, even though they’re expressed in different words. And so on and so on. By continuing along those lines, they could eventually work out what the words mean, what the sonnets mean, why they would disagree with some of them, they would agree with others. And so they would be creating knowledge of what unseen thing caused the seen thing. And precisely, they weren’t just satisfied with being able to predict they were dissatisfied until they discovered the reason for the regularities, the reason why sentences aren’t longer than a certain length, the reason why there were the same kind of phonemes at the ends of words, certain words and not other words.
David Deutsch
They’d realize that there are inexplicit ideas as well as the explicit ones. I could go on about what poetry is, but there’s no reason why they can’t discover it. And they, that’s what, that’s the kind of thing if they spend their lives analyzing this book, that’s what they’re looking for. They’re not looking for these regularities as you imagine them. And as you imagine Newton and Descartes looking for, that’s not what they were looking for. They wanted to know what is in the world that causes these appearances, the same as what your imaginary scientists would be looking for. That’s the reason that they’re spending their lives trying to analyze this book rather than trying to analyze the exact pattern of sand on a sandy beach.
Alex O’Connor
Yeah. So a bit like how a sort of prehistoric person might have discovered that if they put food on the fire, that it cooks and hardens it. And so they can predict that with regularity, that if I put this bit of meat on the fire, it’ll harden and it will be chewy. But even in developing a very sort of rigorous prediction policy that is routinely confirmed, they’re not doing science because they haven’t explained anything and they don’t care to explain anything. They’re just making predictions.
David Deutsch
Yes. But as I said, they can explain the role that this might play in their future diet. Yeah. And that’s already an explanation that they have not observed.
Alex O’Connor
Sure. I see. And I suppose, yeah, the person who’s uncovering the Shakespearean sonnet is eventually going to do more than just make predictions about what they’re going to see on the next page. Absolutely. They’re going to want to know why that’s the case. Yes.
David Deutsch
And that is the defining quality of science. Yes.
Alex O’Connor
Because again, that analogy with the conjuring trick, the magic trick on stage, we kind of brushed over that a second ago. I meant to really emphasize this for people listening because I think it’s really interesting in spelling out this distinction. You can predict the outcome of a magic trick. If a magician puts a ball in a cup and moves it to the left-hand side of the table, you can predict that the ball’s actually going to be in the right-hand side of the table because it’s a magic trick. And you can predict that with accuracy. But the whole point is that even then you have no idea how he did it. I’ve seen a Penn and Teller show. One of the things that Penn and Teller do well actually is they manage to know that you do predict the outcome and still subvert it. So they’ll sort of go like, so where’s the cup? And the clever audience will just know that they’re doing a trick and go, well, I bet it’s on the unexpected one. And they’re like, nah, it’s, come on, use your brain. It’s where I put it. So again, there are assumptions brought to the table. They made an elephant, quote unquote, disappear. And the way they did it was they dressed up a cow as an elephant. They’d been talking all night about how they were going to disappear an elephant. And it was a bit, you kind of think they can’t be serious. And then there’s a cow on stage that’s dressed up as an elephant. And it’s like, okay, very funny and all. And then they cover up the elephant, quote unquote, and they say, now what’s going to happen is the elephant’s going to disappear and it’s going to be replaced with a common farmyard animal. And okay, very funny. But then they drop the curtain and the whole thing has been replaced with a chicken. The cow dressed up as the elephant has disappeared and it’s just a chicken that’s on stage. So it’s like this great Gettier case of justified true belief that you’re about to see a farmyard animal, but managing to subvert that expectation. But again, in fact, to be fair, when I was watching that show and they made the joke about the common farmyard animal, I actually thought to myself, I bet they’re making a joke and it is actually about to be replaced with something like a chicken. So I predicted the outcome of that event. I have absolutely no clue how on earth they did it. So prediction is not the same thing as explanation. And if all I can do is predict the outcome of a magic trick, that’s pretty uninteresting either to somebody who wants to do magic themselves or cares about the mechanism of the magic show. And I suppose the scientist is the person who wants to know how the universe works, wants to do science and wants to understand the mechanism of how things interact. I’m glad to end on a point of agreement there. I mean, I still need to do some more thinking about how this might affect my view of what science is and what it does and how it might one day explain the origins of the universe and all of that kind of good stuff. But at the very least, I think your book is quite confronting.
Alex O’Connor
I think that’s one of the reasons it’s so popular is that there are all of these assumptions about what science is, instrumentalism, induction, what knowledge is and belief. And your book just confronts all of these things and asks, as most good books do, like, are you sure about that? And it’s a whirlwind, which I think is why it’s so popular. And hopefully people have got a taste of it now, but I’ll leave a link to that book in the description. When did the beginning of infinity come out? Was it 2010? I can’t remember now. Sure. So over a decade ago, this isn’t just like a book tour promotion. This has been sitting around for a while. I just want people to realize that I’m not just saying that because the publishers have asked me to. It really is a popular text that’s become a bit of a modern classic. So I’ll leave a link to that in the description. But thanks again for joining me. It’s been another well-rounded conversation.
David Deutsch
Well, thanks for having me. A fascinating conversation as usual.
Alex O’Connor
Yeah. Yeah. And hopefully at some point we can perhaps do it again, because as I’m sure will always be the case, no matter how many times we ever sit down, there is more to talk about. So until the next time, I suppose. Yes. To get early ad-free access to episodes, as well as supporting the channel at the same time, subscribe to my sub stack at alexoconnor.com. Watch more episodes by clicking the link on your screen. Thanks for watching and I’ll see you in the next one.
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