2018-07-24 Visionaries with John Lobell David Deutsch
Duration: 00:54:33
Transcript
John Lobell
[music] Good morning and welcome to Visionaries. I’m John Lobell, your host, and you’ll find us here on the Progressive Radio Network at prn.fm every Monday at 10 a.m. That’s 10 a.m. New York time. I gather for our guest it’s 3 in the afternoon. We’ll speak to him in a minute. And you can catch our back shows at visionaries.podbean.com And be sure to download our app. So our guest today is physicist David Deutsch who pioneered quantum computing by formulating a quantum Turing machine. And I first became aware of him when I discovered his book, The Fabric of Reality. So David, welcome to Visionaries.
David Deutsch
Hi, nice to be here.
John Lobell
Why don’t we start with The Fabric of Reality? That’s a few years back. But tell us what you tried to do with that book and what your thoughts are about it today. The reason I wrote the book is that I had thought that …
David Deutsch
Several things, several strands of knowledge that were in themselves considered to be deep, some of the deepest things we know, like the theory of knowledge itself and the theory of evolution, the theory of computation, quantum physics, those four things were actually intimately related to each other. So that you couldn’t properly understand any of them without the others. And this was inspired actually several years before by a series of lectures given by my old boss, Bryce DeWitt, in Texas. And he gave some lectures called Quantum Theory of Everything, which was purely physics. But if you looked at the philosophy behind this idea that quantum theory, that there is a quantum theory that applies to everything, then it had much wider ramifications.
John Lobell
So it’s interesting that when we read history of science and philosophy, the impact that Isaac Newton had with all of these enlightenment thinkers rushing to bring a kind of Newtonian rationality to every aspect of science, thought, human society. And there’s been maybe we’ve been more timid about quantum theory. So how do you, what was your thinking about a quantum theory of everything and how has that unfolded for you?
David Deutsch
Well, I think we’ve been much worse than timid. In the 20th century, something really terrible happened to philosophy. It stopped being about anything and started being about how to prevent people from making arguments, prevent people from talking about what’s true and false, and so on. And this infected physics as well, because this is sort of logical positivism or that kind of idea. And it came along at the same time as quantum theory. And quantum theory has never fully recovered from that, although the recovery, physics being physics, it never fully succumbed to this. But on the other hand, it hasn’t fully recovered to this day. So I think that the…
John Lobell
So how would you describe the negative impact of logical positivism on thinking about quantum theory?
David Deutsch
It made it legitimate to adopt, first of all, the ideas of Niels Bohr, one of the pioneers of quantum theory, his idea about what quantum theory meant, which came to be known as the Copenhagen interpretation. And that, among other things, said that certain types of explanation were not legitimate. They were not supported by reality. And in particular, when one does an experiment, one sets up the experiment and then one observes the outcome, it was illegitimate, according to the Copenhagen interpretation, to ask how the outcome was brought about, given how the experiment started out. And that meant that the basic question of science, namely, what is there in the world? What does it do? How does it work? And how does it account for what we observe? That whole class of questions was illegitimate. And that put a damper, at least, on progress in understanding quantum physics, and in some respects held it up altogether.
John Lobell
Do you think that was, in part, to protect scientists, to protect themselves from some of the weirdness of quantum theory?
David Deutsch
Although I don’t think that that excuse covers it, because again, round about the same period, relativity came along, and like quantum theory, it was the best description of reality that had yet been made. It was completely superior to all previous theories. It was extremely counterintuitive, in my view, more counterintuitive than quantum mechanics. And yet, the physics community adopted it without much murmur. I mean, there were a few diehards, as there always are. But most working physicists took relativity on board, not only as a means of making predictions, but into their world view. In quantum mechanics, that just didn’t happen.
John Lobell
Are you familiar with Adam Becker’s book, What is Real?
David Deutsch
No, I’m not.
John Lobell
It’s a good presentation of exactly what you were just saying, and describes Hugh Everett, John Bell, and David Bohm, and the hard time they had. How, you know, sort of the inside politics of science and what happened to them and their ideas. So I gather you’re always described as a major proponent of the many worlds approach to quantum theory. So could you describe how that sort of came out of this maybe quantum weirdness and where it stands, what the ideas, and maybe where it stands in terms of the politics of science?
David Deutsch
As I said, the Copenhagen interpretation and the other interpretations that it gave rise to later on, all have the property that they refuse to explain what happens in between observations. And that is for a very good reason, because there isn’t, one can prove that there isn’t an explanation that is entirely in terms of a single universe, which means in this case, never mind the universe, just in terms of the experiment itself, there is no explanation in terms of the objects that are participating in the experiment that we see. Things like the mirrors and the photons and the detectors of photons. One can prove that no story about what they are doing can explain what happens from the beginning of the experiment to the end, including the part that one doesn’t observe.
John Lobell
So let me just interrupt and describe for our audience, I’m going to put ideas in your mouth, but I think David’s talking about experiments where photons are sent out and hit mirrors and beam splitters so that they split into two and then interact with each other and then just do really weird things.
David Deutsch
That’s right, or rather they are weird if one tries to explain them, if one tries to account for what happens just in terms of the things that we see. And the so-called many universes interpretation proposed by Hugh Everett explains the results by saying that at the intermediate stages of the experiment, well first of all by saying that whenever we do such an experiment there are multiple copies of us, instances of us also doing the experiment in universes that we can’t directly detect except via these interference experiments. And during the interference experiment, during the interference phenomenon, objects from the other universes interact with ours and cause the outcome to be as we observe. So that explains what happens in between when we set up the photon, when we put it into the apparatus and when we observe it coming out.
John Lobell
Now this many universes, it’s not just that there’s a universe in which Germany won World War II, but that really at every particle interaction of which there are countless, I don’t know if we should use the word infinity, but that at every one of countless particle interactions there are countless universes spin off?
David Deutsch
Yes, nowadays we find it easier to talk in terms of a multiverse rather than universes. The reality consists of a multiverse which in parts of it are sort of autonomous and don’t notice the other parts at least on a gross scale. And those parts that behave roughly independently of the rest of the multiverse we call universes. Now when things happen like a beam splitter splits the photon in two, all that’s happening is that the universe, that’s happening in a whole sheaf of universes and it’s not that the whole universe bifurcates into two, it’s that of that sheaf of universes in which the photon hit the beam splitter, in half of them it does one thing and in half it does the other. So the universes differentiate from each other rather than new universes being created. And what’s more, the universes continue to be identical except for that photon and the differences between them only start spreading out when that photon further interacts with something differently according to which direction it went in.
John Lobell
Right, so there’s got to be a lot of universes out there by now.
David Deutsch
Well it’s a continuum, it’s no big deal, it’s just like asking in Newtonian physics how many points are there between A and B, well there’s an infinite number but we don’t think that’s very mind-boggling because although there’s an infinite number, there’s a finite measure of them, you know, there’s only a few meters, I only need to move a few meters to cross the room even though I’m passing through an infinite number of points to do so. And the infinity of the multiverse is no different from that in principle.
John Lobell
So let’s, picking up on this multiverse, one of the questions might become, okay, does it matter? And I’m going to describe an idea I put in, I express as yours and tell me if I have it wrong. But I like to say David Deutsch explains the prodigious power of a quantum computer by saying that it harnesses its siblings in parallel universes. So let me know if I got that right and if so, what is a quantum computer and how does it do that?
David Deutsch
That is exactly right and this idea that, well, the interference effects, we spoke just now about interference effects between a photon, a single photon and its counterparts in other universes in an interference phenomenon, they interact with each other and cause each other to do things that they wouldn’t do if the others weren’t there. Now, if you do, if you imagine a slightly more complicated experiment and the first person I think to imagine this sort of thing was Richard Feynman. If you imagine that they don’t just, the photon just doesn’t go in two different ways through a beam splitter. But on these two different ways, it does something like it does a computation. A photon couldn’t do much of a computation, but something with more internal degrees of freedom could do a computation while it was on its way. And it could do a different computation depending on which way it went. And so you’d get two computations happening in parallel. And when they join together again in the interference phenomenon, the result could be something that depends on both of the computations. And that was the idea that I introduced then. That was the first quantum algorithm. It was an algorithm that did in one step what classically one could only do in two steps. Not a very impressive speed up. But as far as theory goes and as far as philosophy goes, that’s already the whole power of quantum computation right there.
John Lobell
Could you describe where that idea you just described stands in relation to Shor’s algorithm, which came first and how does it sort of unfold into?
David Deutsch
The simple thing I described came first. I proposed it in 1984 or 1985. Shor’s algorithm came something like a decade later. But it is much more impressive because Shor’s algorithm is a thing that you would perform by using a fully fledged quantum computer, which would have thousands of qubits rather like having thousands of photons, all of them connected to each other. And it’s sometimes mistakenly said that it would factorise numbers by trying all the possibilities. That actually doesn’t work. A quantum computer could do that, but it couldn’t then deliver the result into each universe. The interference phenomenon just won’t do that for you. But he thought of a clever mathematical trick whereby you could get the computer not to actually factor, try different factors in different universes, but do a certain computation in different universes, slightly different in each universe. And then the interference phenomenon would deliver the factors of the number into every universe. So it’s a deterministic thing. And it depends on sub computations having been performed in vast numbers of universes, far more universes than there are atoms in one universe.
John Lobell
And so scientists today are trying to keep track of all these photons or electrons or whatever particle they’re using and have them not bump into anything to get this to work. Right. That’s right. So before we go on to your more recent book, let’s just stick for a moment with Fabric of Reality. And I’m interested in OK, I’m going to be just a bit autobiographical. When I did my master’s thesis on consciousness and culture in the late 60s, there were a few references I used. One of them was Marshall McLuhan’s Understanding Media, which all my colleagues today have heard of but haven’t read it. But then other works like Milic Capek’s The Philosophical Impact of Contemporary Physics, which even though it was written in the 60s, I think is still useful. And I think about sort of a history and genealogy of ideas. So let’s go back. And do you have any take on the impact of Fabric of Reality? Did anybody pick up on it? Carry any of the ideas forward? How do you feel about today about your attempt to synthesize these four? I can sort of see you saying to yourself, these four things are true. Since they’re all true, they must have some relationship to each other.
David Deutsch
No, no, that wasn’t it. OK, go ahead. It certainly I thought they were all true. The fact that they were related to each other came as something of a surprise. OK. And it was because of that surprise that I wanted to write the book. As for what happened afterwards, I perhaps not the right person to ask what impact it’s had on people. But I am constantly being told by people that that book has done something to them. Oh, good. So, you know, for better or worse. I don’t think it is because of me that some strands of it, namely, say, Popper’s theory of knowledge and the Everett interpretation have become more respectable. I have to choose my words carefully here because I think what’s happened is they’ve become more taken seriously. But I don’t think a greater proportion of the professionals in physics or philosophy actually agree with these two theories. They just take them more seriously. So it’s now more of a thing that you know, you can have a paper on Everett and quantum theory. And it won’t be rejected as being philosophy, right, as it might well have been 20 years ago. But if you asked for a show of hands at a physics conference, then of who endorses the Everett interpretation and who endorses others, Everett interpretation gets 10 percent of the hands going up now. And it did 20 years ago as well. And I don’t understand this phenomenon. You know, if one would think that if the argument in favor of it is good, then it should gradually go to 100 percent. And if the argument is bad, it should gradually go down to zero. Yeah. But that hasn’t happened. And another strange thing is that the supporters, the endorsers of Everett tend to be the younger people in the audience. And so, you know, we were thinking originally, oh, the younger people, OK, the older people are going to die out. And but it doesn’t happen that way. I don’t know if it’s that the younger people change their minds or that the ones who believe Everett leave the field or I don’t know what it is. I only know of one person who I’m specifically aware of who endorsed Everett at one point and then changed his mind. In every other case, it’s always been in one direction, and yet it stays at 10 percent.
John Lobell
So go figure. So talking about the influence of a book, I want to bring up Stephen Wolfram’s A New Kind of Science. And he uses one dimensional cellular automata to demonstrate an idea that perhaps nature is rule based. And so he develops this idea in this book. And I’ve sort of been looking for the influence of his book. And maybe there’s a little he’s certainly carrying it further with Wolfram Alpha and things like his Wolfram natural language programming language. But one of the things he does is he rejects as uninteresting to him quantum theory. And you’ve done something which is, shall I say, taking quantum theory seriously. In other words, if this is true, it’s got to be true of everything. It’s fundamental and we can redo everything from a quantum point of view. So I gather one of the things you’re doing to try to unfold this is what you call constructor theory and see if you can describe for us what you mean by that.
David Deutsch
Hello. Yeah. Oh, OK. We were cut off. Oh, sorry about that.
John Lobell
So I was asking if you could describe your constructor theory.
David Deutsch
Ah, yes. So I originally called this quantum constructor theory because I had originally thought that the quantum theory of computation contained within itself the whole of physics. And that’s because a universal quantum computer is universal. And therefore, the set of all physical objects and all behaviors of physical objects is sort of isomorphic to the set of all programs for this single object. The universal quantum computer. So I thought, you know, the whole of physics is contained in the quantum theory of computation, including classical computation. Yes, yes. So the quantum theory of computation contains a lot more than just physics because it contains a whole load of physical, a whole lot of mathematical relationships that aren’t instantiated in physics other than in quantum computers. So, yes, I thought it encompassed everything. But then I realized that the tiny detail is really a massive story, which is that when you have a quantum computer program that even if it does correspond to something physical in order to decide what physical object that corresponds to, you need a theory of physics, which is beyond the quantum theory of computation and therefore the quantum theory of computation is not the whole of physics after all. So I thought I would set out to improve the quantum theory of computation so that it did include the whole of physics by adding to it a theory of which objects correspond to which programs that was going to be quantum constructor theory. And then I slowly realized that in order to make it universal in that sense, it had to be more than just a generalization of quantum theory. And so then I eventually dropped the quantum constructor theory and just developed a constructor theory, which is a deeper way of understanding the physical world. It’s a deeper way of expressing laws of physics, principles of physics and beyond physics and again into epistemology theory of evolution and so on. It’s a very powerful formalism and but more important, a way of thinking about laws and principles of nature.
John Lobell
So how much of that can you describe to us that we can sort of get a grip on?
David Deutsch
Well, now the way I mainly see it is that physics until now, or let’s say between Galileo and the present day, the basic idea of what an explanation in physics consists of is that it consists of some kind of law of motion and which you apply to initial conditions to tell you what will happen later, or you can apply it to what happens now to tell you what happened earlier and so on. So it sort of relates the state of the world at two different times by expressing a law of motion between them.
John Lobell
So that’s like a law of motion and a bunch of billiard balls.
David Deutsch
Yes, yes, that is the current prevailing conception of fundamental physics and in fact fundamental everything.
John Lobell
Right down to Feynman diagrams.
David Deutsch
Yes, yes, exactly. Now, it has been known for a century at least that there are some things that we know in physics that are either difficult or fundamentally impossible to even express in those terms. The most obvious one is the question, what are the initial conditions of the universe? You can’t explain the initial conditions of the universe by saying, well, before there was this and then there were laws of motion and then we got the initial conditions. So, you know, the initial conditions can’t be explained that way. Another thing that can’t be explained is thermodynamics. In thermodynamics, you have irreversible processes like when you break an egg. You can’t put the egg back together again by reversing what you did with it, particularly if you scramble it. Yeah. Well, even if you just break it and, you know, it comes out, then I mean, you might be able to reverse it by picking out individual atoms and moving them back to where they were. But that would not be the same process that you broke it by breaking. It is much easier breaking it and scrambling it, if you like, is much easier. And people have been trying for over a century to reconcile. And so what I’ve just described is a consequence of the second law of thermodynamics. And people have been trying to reconcile that with the fact that we know that the laws of motion are time reversible. So whatever is a permitted motion of eggs or anything else, the reverse is also permitted motion under the laws of motion. And yet, in practice, you just can’t achieve that motion. So classical physics tries to explain this statistically. Yes, yes. Well, it tries to explain in many ways, none of which work. So statistically, the trouble with that is that it will only tell you what will probably happen and what will probably happen is not what actually happens. So if you it’s never what actually happens, if you toss a coin a thousand times, you will never get exactly five hundred heads.
John Lobell
But classical physics did tell us the broken glass can reassemble. It’s just very unlikely.
David Deutsch
Yes, again, the very unlikely is the thing that the laws of physics know nothing about. The bad interpretations of quantum theory tried to introduce probability into quantum theory. But that was a mistake. And in the many universe interpretation, there is no probability. So but in constructor theory, we change our perspective away from this idea of initial conditions plus laws of motion being the only legitimate way of explaining things. And instead, the dichotomy. So that would be initial conditions plus laws of motion distinguish what happens from what doesn’t happen. Now, in constructor theory, the idea is you have a completely different kind of explanation instead of distinguishing what happens from what doesn’t happen in this initial plus final mode. You ask what is possible and you want to distinguish that from what is impossible. So what is impossible is a thing that’s forbidden by the laws of nature. And what is possible is what is permitted by the laws of nature. And what actually happens is then an emergent property of what can happen. So, for example, one of the laws, it’s another of the laws that’s very difficult to state in the conventional way of doing physics is the law of the universality of computation, the mere fact that there exists a machine that can, the thing that started me off on this path, there exists a machine that can mimic the behavior of any other machine with arbitrary accuracy. That is very difficult to state because the machine that does this is not a particle. It’s a very complicated object. And the more accurate you want it to be, the more complicated the machine has got to be. And yet the law about that machine is very simple, conceptually very simple. And in constructor theory, it’s also very simple.
John Lobell
So I got some questions for you. But before I do that, excuse me, let’s introduce our guest again. My name is John Lobell. You’re listening to visionaries and our guest today is David Deutsch. And just a few places to go look. Obviously, you could start right now with Wikipedia, but I also recommend John Brockman’s edge.org. There are a few great articles by Deutsch on there and then Deutsch’s own website, Constructor Theory.org. So you can follow up on our guest. And let me now ask about this. I guess you’re talking about a Turing machine can emulate any other universal computational process. Is a Turing machine limited by the fact that it’s not a quantum computer and you would need a quantum Turing machine to really be able to emulate any other? Yes.
David Deutsch
Yes, the Turing machine as originally envisaged by Turing is equivalent to the universal quantum computer in regard to computations on integers, which is what Turing was originally interested in because of the way that idea arose. But there are other kinds of computation and such as cryptography and so on, where the quantum computer is inherently superior. It’s often called the quantum Turing machine by analogy with Turing’s. But I think that’s a terrible misnomer because one can also build Turing machines using quantum hardware and that would have certain advantages and so on. But that’s not the same as a universal quantum computer. So I always campaign for the terminology universal quantum computer, not a quantum Turing machine.
John Lobell
Right. You know, it’s interesting. My mind is wandering right now and I’m thinking back on I’m wondering if we lost anything when we abandoned analog computers where battleships in World War II had huge metal disks that rotated and tilted with ball bearings rolling around them to do the computation for aiming the guns before they had digital computers. And I’m thinking about I guess when Feynman introduced the concept of a quantum computer, what he was thinking was if a computer is going to emulate reality, reality is quantum. Therefore, the computer would have to be a quantum computer. So tell us some more about your thoughts about what it means to fully dive into realizing that we’re in a quantum world.
David Deutsch
Yes. First of all, we haven’t lost anything by losing analog computers. In fact, that’s an integral part of the story. And it’s one of the things that connects the theory of evolution with quantum theory, basically digital computers. It’s only digital computers that can be error corrected. Analog computers are inherently not error correctable. And therefore, if you have a long computation on an analog computer, errors are going to build up and that eventually limits the scope of the possible computations that it can perform. Now, the equivalent of that issue in the theory of evolution is that Darwin was unaware that genes are digital. Right. It was actually known at the time, but he didn’t know about it.
John Lobell
He thought they blended.
David Deutsch
Yes, he thought they blended. And he was aware that this is a problem, that this would give rise to a problem with error correction. He didn’t know how to solve it. And as always with Darwin, he was honest enough to say, you know, he didn’t try to fudge this. He didn’t know what the answer was. I don’t know much about the history of this, but I understand that Mendel and so on had already happened.
John Lobell
Yes. And Darwin just neglected to read his paper. Right. Right.
David Deutsch
Now, so can you describe now we know that evolution, which requires faithful copying from generation to generation, can only take place digitally. And in fact, DNA does digital computation and has built-in error correction. Yes, yes, very much so.
John Lobell
Now, do you apply this evolution beyond DNA biology? Is it something that happens in the universe, the solar system, galaxies, or is it unique to biology?
David Deutsch
Neither. It’s not unique to biology. There have been ideas about applying it to physics in the large, like Lee Smolin has some ideas about the universe reconstituting itself through black holes and so on. I’m skeptical about all that. But evolution does also happen in the realm of ideas. And in fact, evolutionary theories about the evolution of ideas again predate Darwin. But again, they all used the wrong theory of evolution. It has to be Darwinian evolution, not Lamarckian. So Richard Dawkins introduced the concept of memes, a meme being a kind of idea that can be copied from one person to another. But memes, although the same theory applies to them as does to genes, the actual natural history of memes, as it were, is completely different from that of genes, because the copying happens in a different way. We don’t copy an idea from one mind to another. Even if you told me something and I learned it off by heart, I would not have in my mind the same idea that you had. And that fact dominates the transmission and evolution of memes.
John Lobell
Interesting. So we have a little bit more time left, and maybe I’ll try to persuade you to come on again in the future because we have a huge topic. We haven’t even gotten to yet. And that is I described David wrote a book called The Fabric of Reality, but he wrote another book called The Beginning of Infinity, which is a monumentally important book. So, David, what were you trying to do in The Beginning of Infinity and what prompted you to write that?
David Deutsch
So The Fabric of Reality was about four things. And The Beginning of Infinity is about lots of things which have one theme in common, which is progress. So it’s about the different ways, the different senses in which progress has happened and can happen in science, in morality, in economics and also in the universe. And that they all have, again, various laws in common that they’re sort of they’re all best understood in the light of each other. And the but it extends into the future. So it’s kind of applying the ideas of The Fabric of Reality. But the common theme is different. It’s not the same basic theory, but the same idea of progress in all of them. And so that I explore various ideas of progress, especially the enlightenment, the 17th, 18th century enlightenment. And I have a slightly different take on it from most people, which I basically got from the historian Roy Porter, who thinks that what’s usually called the enlightenment is actually two different phenomena, both of which are a rejection of absolutism and tyranny and authoritarianism that went before, but are actually also opposed to each other.
John Lobell
So one of those ideas. Yes. Sorry. What are those two opposing ideas? Yeah.
David Deutsch
So both of them were rebellions against authority. One of them. Well, there’s several ways of thinking about what the difference was. One of them was utopian and the other was open ended. So one of them sort of had the idea that everything that’s wrong with the world is because of tyranny and authority and monarchy and aristocracy and so on. And that if those were abolished, then the world would be fine. Whereas the other and that was sort of the European, that was the idea that underlay things like the French Revolution or the debacle of the French Revolution. Yes. But this is I mean, the people who had hopes were not hoping for the terror and that kind of thing, that they were hoping for a good world. Right. And that characterized both wings of the Enlightenment. The other wing, which was sort of centered in England and Scotland, but also maybe originated in the Netherlands, was an idea of not that we could get to an ideal state, but that we could improve our state, but only to a state which could itself be improved. So there you although you need to remove the impediments to progress, you need to do it in such a way that doesn’t destroy the ability to remove impediments. And that led to an evolutionary idea, which so in let’s say, you know, when I say these things were centered in England and Scotland and Netherlands, I’m not referring to the individuals. There were people who were adherents of both enlightenments in every country in the civilized world and opponents in every country and also advocates of the old system as well. So one of the differences this led to is that when you think that you’re heading for a utopia, for the final state, what you do is, the idea is, you look for the people who are your enemies at the moment and you try and kill them all. So the idea was, you know, we remove the aristocracy, we remove the priests, and so on. And what is left will be good. Whereas the Anglosphere sort of way of approaching the problem of rebelling from authority or how to approach the rebellion from authority was to extend privileges which were previously confined to the aristocracy to everybody. So there were in the Anglosphere, there were waves of egalitarianism where the vote was extended and property rights were extended, rights were extended from men to women. That was the kind of thing where and you know, and we have the phrase the Englishman’s home is his castle. That was because for hundreds of years an aristocrat’s home had been his castle literally. And he was the lord of his own domain. Gradually, the idea was that everybody was the lord of his own domain, if only a smaller one. And that led to an individualism. And whereas the continental enlightenment led to a collectivism. So that’s some of the themes.
John Lobell
So, fantastic. Now there are two things. One is for our audience. David extends this out to, you know, once you have this idea, if it keeps going, the reason his title is beginning of infinity is, you know, you can maybe eventually build Dyson spheres and reengineer the universe. But I want to ask you, there are a couple of books along a similar theme of yours. I’m thinking of it that are coming out now. Steven Pinker’s Enlightenment Now. And I have a feeling of I agree with both of you on the Enlightenment, but I have a maybe I’m more pessimistic than both of you in that I feel it’s very fragile. You seem to be rather confident it’s going to keep going. So how do you feel about confidence versus fragility in the continuation of what the Enlightenment has opened?
David Deutsch
I think in this sense that you’re saying here, I am a little more pessimistic than Steven Pinker. Although I think if you ask him straight out, does he think that there’s anything inevitable about progress, he will say, of course not. And if you ask, well, can we say that progress is likely? I don’t know what he’d say. He might well say, well, yeah, it’s quite likely and so on. Whereas my view is. Progress is possible. But we can mess it up. It’s been messed up before. And there’s not only no reason to think that it’s inevitable, but there’s no meaning to say that it’s likely. This would be one of those misuses of probability. All we can say is what’s possible and what isn’t possible.
John Lobell
So that’s why your book and his book are important that we understand where it came from so that we don’t mess it up.
David Deutsch
Yes. And it has been messed up before. Every single time except the present, the instances of enlightenment were messed up. So none of them lasted as long as ours. So, you know, that’s a reason for hope.
John Lobell
Yeah. So just in a few minutes remaining, what are some of the things your book, The Beginning of Infinity, sees? What does it mean, infinity, The Beginning of Infinity? Where does it, to infinity and beyond, where does it take us?
David Deutsch
Beyond? First of all, I think that infinity has a completely undeserved reputation for being mysterious and woo woo. Infinity was introduced in mathematics and in physics as a way of simplifying ideas. Like I said, rather than think of crossing the room as an infinite number of things and worrying about how that’s possible, like Zeno did in antiquity. We realize that the laws are about feet and inches, not about points. And so we have only a finite number of feet and inches. So on the other hand, infinity is somewhat counterintuitive in that when you have an amount of something, no matter how large it is, it never gets any closer to infinity. So this applies in all sorts of ways. So in regard to progress, in regard to technological progress, that means that we’re always at the beginning, no matter how well we do, no matter how much power we get in our fundamental understanding or in our technology. We are always at the beginning of what is possible. And as Karl Popper says, in regard to knowledge, although we may differ in various ways in the knowledge that we all have, we are all alike in our infinite ignorance. And I think that is a very important egalitarian implication of the theory of knowledge that because there’s infinity ahead of us, we are all alike in our ignorance. We’re also all alike in our fallibility. So no matter how much knowledge you have, you may be mistaken about any particular thing. Fantastic.
John Lobell
You know, there’s a critic of Ray Kurzweil’s exponential curve. And he says, oh, we’re just at the knee and we’re about to go straight up. Someone had pointed out, depending on how you draw the curve, we’re always at the knee. There’s no such thing, you know, that there’s no such thing as a special point.
David Deutsch
Well, I think Kurzweil’s idea, which I disagree with, is that we’re going to go faster than exponential. Yeah, right.
John Lobell
So our guest has been David Deutsch. David, anything you want to leave our audience with. And after you do that, I’ll well, let’s do it right now. Look up David on Wikipedia. Go to Brockman’s edge.org and search on his name and go to. Constructor theory dot org.
David Deutsch
Oh, yeah, there’s also my own website. Oh, and that is David Deutsch dot org dot UK. But I mean, all those things link to each other. So you just need to find one of them.
John Lobell
Great. So what do you want to leave our audience with?
David Deutsch
Well, I want to leave everybody with a sense of optimism that there is. All the problems in the world are just problems and are caused by lack of knowledge. There is never a brick wall that we’re up against, except the laws of physics and the laws of physics do not have it in for us.
John Lobell
Well, we’ll manage without exceeding the speed of light.
David Deutsch
Exactly right.
John Lobell
So David, thank you very much. And this has been Visionaries. Tune in again next week. Thank you.
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