Making Sense with Sam Harris - #22 — Surviving the Cosmos

Episode Date: December 16, 2015

Sam Harris talks to physicist David Deutsch about the reach and power of human knowledge, the future of artificial intelligence, and the survival of civilization. If the Making Sense podcast logo in your player is BLACK, you can SUBSCRIBE to gain access to all full-length episodes at samharris.org/subscribe.

Thank you. of the Making Sense Podcast, you'll need to subscribe at samharris.org. There you'll find our private RSS feed to add to your favorite podcatcher, along with other subscriber-only content. We don't run ads on the podcast, and therefore it's made possible entirely through the support of our subscribers. So if you enjoy what we're doing here, please consider becoming Today I'm speaking with David Deutsch. David is a physicist at Oxford. He's a professor of physics at the Center for Quantum Computation at Clarendon Laboratory. And he works on the quantum theory of computation and information. And he is a very famous exponent of the many worlds interpretation of quantum mechanics, neither of which do we talk about in this

interview. David has a fascinating and capacious mind, as you will see, and we talk about much of the other material in his most recent book, The Beginning of Infinity, and we by no means cover all of its contents. But as you'll see, David has a talent for expressing scientifically and philosophically revolutionary ideas in very simple language. And what you'll hear in this interview is often me struggling to go back and unpack the import of some very simple sounding statements, which I know those of you unfamiliar with his work can't parse the way he intends. In any case, I hope you enjoy meeting David Deutsch as much as I did. David, thank you for coming on the podcast. Oh, thank you very much for having me.

Listen, I've been, I don't know what part of the multiverse we're in where I can complain about jihadists by night and talk to you by day, but it's a very strange one we seem to be in at the moment because we're about to have a very different kind of conversation than I've had of late. And I really have been looking forward to it. I spoke to Steven Pinker, told him that we were going to speak and he claimed that you are one of his favorite minds on the planet. I don't know if you know Steven, but that's high praise indeed. I don't know him personally, but that's very kind of him to say that. So let me begin quite awkwardly with an apology, in addition to the apology that I just gave you off air for being late. While I aspired to read every word of your book, The Beginning of

Infinity, before speaking with you, I've only read about half, not just the first half. I jumped around a bit, but forgive me if some of my questions and comments seem to ignore some of the things you had the good sense to write in that book and that I didn't have the good sense to read. Not much turns on this because, as you know, you have to make yourself intelligible to our listeners, most of whom will not have read any of the book but I just want to say that it really is a remarkable book I mean both philosophically and scientifically it is incredibly deep while also being extremely accessible thanks and it is a profoundly optimistic book in at least one sense. I don't think I've ever encountered a more hopeful statement of our potential to make progress. But one of the consequences of your view,

if I'm not mistaken, is that the future is unpredictable in principle, and that the problems we will face are unforeseeable, and that the way that we will solve these problems is also unforeseeable, and problems will continue to arise of necessity, but problems can be solved. And this claim about the solubility of problems with knowledge runs very, very deep, and it's far deeper than our listeners will understand based on what I've just said. That's a very nice summary. It's interesting to think about how to have this conversation, because what I want to do is kind of creep up on your central thesis. And I think there are certain claims you make, claims specifically about the reach and power of human knowledge that are fairly breathtaking. And I find that I want to agree with every word of what you say here because again, these claims are so

hopeful. But I have a few quibbles and it's interesting to go into this conversation hoping to be relieved of my doubts about your thesis. I'm kind of hoping that you'll perform an so hopeful. But I have a few quibbles, and it's interesting to go into this conversation hoping to be relieved of my doubts about your thesis. I'm kind of hoping that you'll perform an exorcism on my doubts, such as they are. Sure. Well, I think the truth really is very positive, but I should say at the outset that there is one sort of fly in the ointment, and that is that because the future is unpredictable, nothing is guaranteed. There is no guarantee that civilization will survive or that our species will survive. But there is, I think, a guarantee that we can, and also we know in principle how to.

Before we get into your claims there, let's start the conversation somewhere near epistemological bedrock. I'd like to ask you a few questions designed to get to the definitions of certain terms, because you use words like knowledge and explanation and even person in novel ways in the book. And I want our listeners to be awake to how much work you're requiring these words to do. Let's begin with the concept of knowledge. What is knowledge? And what is the boundary between knowledge and ignorance, in your view? Yes.

So there are several different ways of approaching that concept. I think that the way I think of knowledge is broader than the usual use of those terms, and yet paradoxically closer to the common sense use of the term, because philosophers have almost defined it out of existence. Knowledge is a kind of information. That's the simple thing. It's something which could have been otherwise and is one particular way. And the

particular way it is, is that it says something true and useful about the world. Now, knowledge is in a sense an abstract thing because it's independent of its physical instantiation. I can speak words which embody some knowledge, I can write them down, they can exist as movements of electrons in a computer and so on, thousands of different ways. So knowledge isn't dependent on any particular instantiation. On the other hand, it does have the property that when it is instantiated, it tends to remain so. So the difference between, let's say, a piece of speculation by a scientist, which he writes down, and then that turns out to be a genuine piece of knowledge, that will be the piece of paper that he does not throw in the waste paper basket. And that's the piece that will be published

and that's the piece which will be studied by other scientists and so on. So it is a piece of information that has the property of keeping itself physically instantiated, causing itself to be physically instantiated once it already is. Once you think of knowledge that way, you realize that, for example, the pattern of base pairs in the DNA of a gene also constitute knowledge. And that in turn connects with Karl Popper's concept of knowledge, which is knowledge that doesn't have to have a knowing subject. It can exist in books abstractly, or it can exist in the mind, or people can have knowledge

that they don't even know they have. Right, right. Well, I want to get to the reality of abstractions later on, because I think that is very much at the core of this. But a few more definitions. What is the boundary between science and philosophy or other expressions of rationality in your view? Because I think people are, in my experience, profoundly confused by this, and many scientists are confused by this. So I've argued for years in several contexts about the unity of knowledge, and I feel that you're a kindred spirit here. So I've argued for years in several contexts about the unity of knowledge, and I

feel that you're a kindred spirit here. So how do you differentiate or fail to differentiate science and philosophy? Well, as you've just indicated, I think that science and philosophy are both manifestations of reason, and that the real difference that should be uppermost in our minds between different kinds of ideas and between different kinds of ways of dealing with ideas is the difference between reason and unreason. But among the rational approaches to knowledge or different kinds of knowledge, there is an important difference between science and other things like philosophy and mathematics, not at a really fundamental level, but at a level which is of great practical importance often. And that is that science is the kind of knowledge that can be tested by experiment or observation. Now I hasten to add that that does not mean that the content of a scientific theory consists

entirely in its testable predictions. On the contrary, a typical scientific theory, its testable predictions are just a tiny, tiny sliver of what it tells us about the world. Now Karl Popper introduced his criterion of demarcation between science and other things, namely whether the science is the testable theories and everything else is untestable. And people have, ever since he did that, people have falsely interpreted him as a kind of positivist. He was really the opposite of a positivist. And if you interpret him like that,

then his criterion of demarcation becomes a criterion of meaning. That is, he's interpreted as saying that only scientific theories can have meaning. Right, he's a verificationist. Yes, and yes, so he's called a falsificationist to distinguish him from the other verificationists. But of course, he isn't. It's a completely different conception. And, you know, his philosophical theories themselves are philosophical theories. And yet he doesn't consider them meaningless, quite the contrary. So the difference between science and other things comes up when people pretend to have the authority of science for things that aren't science. But on the bigger picture, the more important demarcation is between reason and unreason. Yeah, I want to go over that terrain you just covered a little bit more because you made some points there that I think are a little hard for listeners who haven't thought about this a lot to parse. And I think those are incredibly important points. For instance, this notion that science reduces to what is testable. This belief is so widespread, even among high-level scientists,

that anything else, anything which you cannot measure immediately, is somehow a vacuous claim in principle. The only way to make a credible claim, or even a meaningful claim, about reality is to essentially give a recipe for observation that is immediately actionable. It's an amazingly widespread belief. So too is a belief in a bright line between science and every other discipline where we purport to describe reality.

And it's like the architecture of a university has defined people's thinking. So the fact that you go to the chemistry department to talk about chemistry, and you go to the journalism department to talk about current events, and you go to the history department to talk about human events in the past, these separate buildings have balkanized the thinking

of even very smart people into thinking that all of these language games are in some sense irreconcilable and that there is no common project. I'll just bounce a few examples off of you that some of our listeners will be familiar with, but I think they make the point. So you take something like the assassination of Mahatma Gandhi, right? Now that that's a historical event. But anyone who would purport to doubt that it occurred, if someone said, well, actually, Gandhi was not assassinated, he went on to live a long and happy life in the Punjab under an assumed name. This is a claim about terrestrial reality that is at odds with the data. It's at odds with the testimony of

people who saw him assassinated. It's at odds with the photographs, is at odds with the testimony of people who saw him assassinated, it's at odds with the photographs we have of him lying in state. And there's an immense burden of reconciling this claim about history with the facts that we know to be true. And the distinction is not between what someone in a white lab coat has said or facts that have been brought into view in the context of a scientific laboratory with a National Science Foundation grant. It is the distinction between having good reasons for what you believe and having bad ones. And it is the distinction between reason and unreason, as you put it. So one could say that the assassination of Gandhi is a historical fact. It's also a scientific fact. It is just a fact. Even though science doesn't usually deal in quantities like assassinations, and you're more a journalist or historian to be talking about this thing being true, it would be deeply unscientific at this point to doubt that it occurred. Yes. Well, I'd say that it's deeply

irrational to claim that it didn't occur. Yes. And I wouldn't put it in terms of reasons for belief either. I agree with you that people have very wrong ideas about what science is and what the boundary of scientific thinking is and what sort of thinking should be taken seriously and what shouldn't. I think it's slightly unfair to put the blame on universities here. I think this misconception arose originally for quite good reasons. It's rooted in the empiricism of the 18th century and before and the origin of science, where science had to rebel against the authority of tradition and of human authority and try to give dignity and respect to forms of knowledge that involved observation and

experimental test. And so empiricism is the idea that knowledge comes to us through the senses. Now that's completely false. All knowledge is conjectural and comes from within at first and is intended to solve problems, not to summarize data. But this idea that experience has authority and that only experience has authority, false though it is, was a wonderful defense against previous forms of authority, which were not only invalid, but stultifying. So it was a good defense, but not actually true. And in the 20th century, a horrible thing happened, which is that people started taking

it seriously, not just as a defense, but as being literally true. And that almost killed certain sciences. And even within physics, I think it greatly impeded the progress in quantum theory. So just to come to a little quibble of my own, I think the essence of what we want in science is good explanation, which, and there's no such thing as a good reason for a belief. A scientific theory is an impersonal thing. It can be written in a book. One can conduct science without ever believing the theory, just as a good policeman or judge can implement the law without ever believing either of the cases for the prosecution or defense, just because they know that a particular system is better than any individual human's opinion. The same is true of science.

Science is a way of dealing with theories, regardless of whether one believes them. And one judges them according to whether they are good explanations. And there need not be ever any such process as accepting a theory, because it is conjectured initially, and takes its chances and is criticized as an explanation, if by some chance a particular explanation ends up being the only one that survives the intense criticism that science has learned how to apply, then it's not adopted at that point. It's just not discarded. Right, right.

I think we may just be stumbling over a semantic difference in how we're using terms like reasons and reasons for belief or a justification for a belief. I understand your quibble here that you're pushing back against this notion that we need to find some ultimate foundation for our knowledge rather than this open-ended effort at explanation. But let's table that for a second because obviously your notion of explanation is at the core here. And again, I just want to sneak up on it because I don't want to lose some of the detail with respect to the ground we've already covered.

Let's come back to this notion of scientific authority because it seems to me there's a lot of confusion about this, about the nature of scientific authority because it seems to me there's a lot of confusion about this, about the nature of scientific authority. It's often said in science that we don't rely on authority, and that's true and it's not true. I mean, when push comes to shove, we don't rely on it, and you make this very clear in your book. But we do rely on it in practice, if only in the interest of efficiency. So if I ask you a question about physics,

I will tend to believe your answer because you're a physicist and I'm not. And if what you say contradicts something I've heard from another physicist, well, then if it matters to me, I will look into it more deeply and try to figure out the nature of the dispute. But if there are any points on which all physicists agree, a non-physicist like myself will defer to the authority of that consensus. And again, this is less a statement of epistemology than it is a statement about just the specialization of knowledge and the unequal distribution of human talent and just, frankly, the shortness of every human life. frankly, the shortness of every human life. And we simply don't have time to check everyone's work. And we have to rely on, in some sense, the faith that the system of scientific conversation is correcting for errors and self-deception and fraud. Yes. Now, okay. I got myself out of the ditch there. Yes. Yes. Exactly. Exactly. At the end, what you said was right. So you could call this authority,

it doesn't matter really what words we use, but every student who wants to make a contribution to a science is hoping to find something where every scientist in his field is wrong. Absolutely. thing where every scientist in his field is wrong. So it's not impossible to take the view that you're right and every expert in the field is wrong. I think that what happens when we consult experts, whether or not you use the word authority, it's not quite that we think that they're more competent. I think when you refer to error correction, that hits the nail on the head. I think that there is a process of error correction in the scientific community that approximates to what I would use if I had the time and the background and the interest to pursue it there. And so if I go to a doctor to consult him about what my treatment should be, I assume

that by and large, the process that has led to his recommendation to me is the same as the process that I would have adopted if I had been present at all the stages. Now, it's not exactly the same. And I might also take the view that there are widespread errors and widespread irrationalities in the medical profession. And if I think that, then I will adopt a rather different attitude. I may choose much more carefully which doctor I consult and how my own opinion should be judged

against the doctor's opinion in a case where I think that the error correction hasn't been up to the standard I would want. And this is not so rare. It's, as I said, every student is hoping to find a case of this in their own field. So every research student. So when I travel on a plane, I expect that the maintenance will have been carried out to the standards that I would use. Well, approximately to the standards that I would use. Well enough for me to consider that risk on the same level as other risks that I take just by crossing the road. It's not that I'm sure.

It's not that I take their word for it in any sense. It's that I have a positive theory of what has happened there to get that information to the right place. And that theory is fragile. I can easily adopt a variant of it. Yeah. And it's also, it's probabilistic. You realize that a lot of these errors are washing out and that's a good thing. But in any one case, you may judge the probability of error to be high enough that you need to really pay attention to it. And often, as you say, that happens in a doctor's office where you're not hoping to find it. Well, again, I still picture us kind of circling your thesis and not yet landing on it. Science is largely a story of our fighting our way past anthropocentrism,

this notion that we are at the center of things. We are... It has been. It has been, yes. We are not specially created. We share half our genes with a banana, and more than that with a banana slug. So as you describe in your book,

this is known as the principle of mediocrity. And you summarize it with a quote from Stephen Hawking who said, quote, we're just chemical scum on the surface of a typical planet that's in orbit around a typical star on the outskirts of a typical galaxy. Now, you take issue with this claim in a variety of ways, but the result is that you come full circle in a way. You fight your way past anthropocentrism the way every scientist does. But you arrive at a place where people, or rather persons, I think that's the formulation you tend to use,

and which you define in a special way, suddenly become hugely significant, even cosmically so. And so say a little more about that. Yes. Well, so it's that quote from Hawking is literally true, but the philosophical implication he draws is completely false because, well, one can approach this from two different directions. First of all, if you think of that chemical scum, namely us, and possibly things like us on other planets and in other galaxies and so on, if they exist, then to study that scum is impossible, unlike every other scum in the universe, because this scum is creating new knowledge, and the growth of knowledge is profoundly unpredictable. So as a consequence of that, to understand this scum, never mind predict, but to understand it,

to understand what's happening here, entails understanding everything in the universe. entails understanding everything in the universe. Because as I say in the book, I give an example in the book that if the people at the SETI project were to discover extraterrestrial life somewhere far away in the galaxy, they would open their bottle of champagne and celebrate. Now, if you try to explain scientifically what are the conditions under which that cork will come out of that bottle, then the usual scientific criteria that you use of pressure and temperature and biological degradation of the cork and so on will be irrelevant. What is the most important factor in the physical behavior of that bottle is whether there exists life on another planet. And in the same way, anything in the universe can affect the gross behavior of things that are affected by people. And so, in short, to understand humans, you have to understand everything. And so, in short, to understand humans, you have to understand everything.

And humans or people in general are the only things in the universe of which that is true. So they are of universal significance in that sense. Then there's the other way around. that the reach of human knowledge and human intentions on the physical world is also unlimited. So we are only used to having a relatively tiny effect on this small insignificant planet, et cetera, and for the rest of the universe to be completely beyond our ken. planet, etc., and for the rest of the universe to be completely beyond our ken. But that's just a parochial misconception, really, just because we haven't set out across the universe yet. And we know that there are no limits on how much we can affect the universe if we choose to. universe if we choose to. So in both those senses, we are, by which I mean we and the ETs and the AIs, if they exist, there's no limit to how important we are. So we are completely central to any understanding of the universe. I'm struggling with the fact that I know how

condensed some of your statements are, and I also know that it's impossible for our listeners to appreciate just how much knowledge and conjecture is being smuggled into each one. So I guess let's just deal with this concept of explanation and the work it does. And I mean, first, there's a few points you make about explanation that I find totally uncontroversial and even obvious, but which are, in fact, highly controversial in educated circles. And one is this notion that, as you say, explanation is really what lies at the bedrock of the scientific enterprise and the enterprise of reason generally. Explanations in one field of knowledge potentially touch explanations in many other fields and even

all other fields. And this suggests a kind of unity of knowledge. But you make two claims, really especially bold claims about explanation, which I do see some reason to doubt. And as I've said, I'd rather not doubt them because they're incredibly hopeful claims. So I guess the first to deal with is the power of explanation. I guess I'll divide these into there's the power of explanation and there's the reach of explanation. And these may not be entirely separate in your mind, but let's just deal with it. There's a separate emphasis here. You make what is a seemingly extraordinary claim about explanation, which at first seems quite pedestrian. You say that there's a deep connection between explaining the world and controlling it. Everyone understands this to some degree. I mean, we all see the evidence of it all around us in our technology.

And people have this phrase, knowledge is power in their heads. So there's nothing so surprising about that. But you do go on to suggest, and you did just suggest it in passing, that knowledge confers power without limit, or it is limited only by the laws of nature. So you actually say that anything that isn't precluded by the laws of nature is achievable given the right knowledge. Because if something were not achievable given complete knowledge, then that itself would be a regularity in nature that could be explained in terms of the laws of nature. So there are really only two possibilities. Either something is precluded by the laws of nature, or it is achievable with knowledge. Do I have you right

there? Yes. And that's what I call the momentous dichotomy. There can't be any third possibility other than those two. And I think you've given not only a statement of it, but you've given a very short proof of it right there. So how isn't this just a clever tautology, analogous to the ontological argument proving the existence of God? So many of our listeners will know that according to Saint Anselm and Descartes and many others, it's believed that you can prove the existence of God simply by forcing your thoughts about him to essentially bite their own tails. And for instance, I could make the following claim. I can form a clear and distinct concept of the most perfect

possible being. And such a being must exist, therefore, because a being that exists is more perfect than one that doesn't. And I've already said I'm thinking about the most perfect possible being. So an existence is somehow a predicate of perfection. Now of course most people will recognize, certainly most people in my audience will recognize that this is just a trick of language. It could be used to prove the existence of anything. I could say I'm thinking of the most perfect chocolate mousse and it must exist therefore because a mousse that exists

is more perfect than one that doesn't and I already told you that I'm thinking of the most perfect possible mousse. What you're saying here doesn't have the same structure but I do worry that that you're performing a bit of a conjuring trick here because, and I'll just ask the question, for instance, why mightn't certain transformations of the material world be unachievable even in the presence of complete knowledge merely by, and this is something I realize you do anticipate in your book, but I want you to flesh it out for the listeners, merely by, let's say a contingency of geography.

So that, for instance, you and I are on an island and one of our friends comes down with an appendicitis. And let's say you and I both, we're both competent surgeons. We know everything there is to know about removing a man's appendix. But it just so happens we don't have any of the necessary tools and everything on that particular island just has the consistency of soft cheese, right? So just by sheer accident of our personal histories, there is a gap between what is knowable and what is in fact known and what is achievable, even though there are no laws of nature that preclude our performing an appendectomy on a person. Why mightn't every space we occupy, just by a contingent fact of the way the universe is, not introduce some gap of that kind? Well, there definitely are gaps of that kind, and they are all laws of nature. For example,

I am an advocate of the many universes interpretation of quantum theory, or the many universes version of quantum theory. And that says that there are other universes which the laws of physics prevent us from getting to. There is also the finiteness of the speed of light, which doesn't prevent us from actually getting anywhere, but it does prevent us from getting anywhere in a given time. So if we want to get to the nearest star within a year, we can't do so because of the accident of where we happen to be. If we happen to be nearer to it, we could easily get there in a year. And in your example, if there's no metal on the island, then it may be, I mean, it's rather a complicated thing to calculate, but there will be a fact of the matter of whether, and it could easily be, that no knowledge present on that island could save the person because no knowledge could transform the resources on that island into the relevant medical instruments. So that's a restriction that the laws of physics apply because we are in

particular times and places. And of course, the most powerful thing is we don't in fact have the knowledge to do most of the things that we would ideally like to do. So that's another restriction. But that's completely different from, I think, what you're imagining, which is that there might be some reason why, for example, why we can never get out of the solar system. Getting out of the solar system, if that were impossible, it would mean that there is some, for example, some number, some constant of nature, 1,000 astronomical units or something, which limits the other laws of nature that we already know. Now, there might be other laws of nature. other laws of nature. When you say, how do we know that there isn't? That's a little bit like, and if I can turn your objection around the other way, that's a little bit like creationists saying, how do we know that the earth didn't start 6,000 years ago? There is no conceivable evidence that

could prove that it didn't, or that distinguish the 6,000-year theory from a 7,000-year theory and so on. There's no way that evidence can be brought to bear on that. And that leads us to explanation again, which is another difference between my argument, which I think is valid, and the ontological argument of the existence of God, that is, as you said, it's a perversion of logic. The argument purports to use logic, but then smuggles in assumptions like that perfection entails existence, for example, to name a simple one. Whereas my proof, as it were, is an explanatory one. It isn't just this must exist. It's that if this doesn't exist, something bad would happen. For example, the universe would be controlled by the supernatural, or the laws of nature would not be explanatory

or something of that kind, which I think is just leading to the supernatural in a different way. So I think the argument works because it's explanatory. There isn't a whole of the same. I mean, you can't prove that it's true, of course, but there isn't a hole in it of the same kind as in the ontological argument. The fishiness I was detecting worries me less than what I'm going to go on to talk about it regarding the reach you posit for explanation, but it's more a matter of emphasis. If you're saying that we could have a complete understanding of the laws of nature, and yet there could be many contingent facts about where we are, let's say a distance or a current distance from a star we want to get to, which would preclude our doing anything especially powerful with this knowledge, and you're going to shuttle those

contingent facts back into this claim about, well, this is just more of the laws of nature. I mean, these facts about us are regularities in the universe, which are themselves explained by the laws of nature, and therefore, we're back to this dichotomy. There's just the laws of nature, and there's the fact that knowledge can do anything compatible with those laws. I guess the concern is, in various thought experiments in your book, you make amazingly powerful claims about the utility of knowledge. So for instance, at one point, you talk about a region of space, a cube the size of the solar system on all sides, that's more representative of the universe as it actually is, which is to say it's nearly a vacuum. It's just we're talking about a cube of intergalactic empty space that has more or less nothing but stray hydrogen atoms in

it. And you talk about the process by which that could be primed and become the basis of the most advanced civilization that we could imagine. You might maybe spend a minute or two just talking about how you get from virtually nothing to something there, but it is a picture of almost limitless fungibility of the universe on the basis of knowledge. And that's a, take us to deep space for a moment. Yes. So you and I are made of atoms and that already gives us a tremendous fungibility because we know that atoms are universal. The properties of atoms are the same in this cube of space millions of light years away as they are here. So we're talking mostly, we're talking about the power of knowledge to achieve things, to control the world, we're not talking about tasks like saving someone's life with just the resources on an island or getting to a distant

planet in a certain time. We're talking about the generic thing that we're talking about is converting some matter into some other matter. So what do you need to do that? Well, generically speaking, what you need is knowledge. What would have to happen is that this cube of almost empty space will never turn into anything other than boring hydrogen atoms unless some knowledge somehow gets there. Now, whether knowledge gets there or not depends on decisions that people with knowledge will make at some point. I think there's no doubt that knowledge could get there if people with knowledge decided to do that for some reason. people with knowledge decided to do that for some reason. I can't actually think of a reason. But if they did want to do that, it's not a matter of futuristic speculation to know that that would be possible. Then it's a matter of transforming atoms in one configuration

to atoms in another configuration. And we're now getting used to the idea that that is an everyday thing. We now have 3D printers that can convert just generic stuff into any object provided that the knowledge of what shape that object should be is somehow encoded into the 3D printer. And a 3D printer with the resolution of one atom would be able to print a human if it was given the right program. We already know that. Although it's

in some sense way beyond present technology, it's not way beyond our present understanding of physics. It's well within our present understanding of physics. It would be an absolutely amazing turn up for the books if that turned out to be beyond physics. I mean, beyond what we know of physics today. The idea that new laws of physics would be required to make a printer is just beyond belief, really. To just take us from the beginning in empty space, you start with hydrogen and you have to get heavier elements in order to get to your printer.

Yes. So it has to be primed not just with abstract knowledge, but with knowledge instantiated in something. We don't know what the smallest possible universal constructor is. That is just a generalization of a 3D printer something that can be programmed either to make anything or to make the machine that would make the machine that would make the machine to make anything etc so one of those with the right program sent to empty space would first convert well first gather the hydrogen presumably by some kind of electromagnetic broom, sweeping it up and

compressing it, then converting it by transmutation into other elements, and then by chemistry into what we would think of as raw materials, and then using space construction, which is the kind of thing that we're almost on the verge of being able to do, into a space station. And then the space station to instantiate further people to generate the knowledge to suck in more hydrogen and make a colony. And well, they're not going to look back from there. How far do you want me to describe this? Right, right. It's just a very interesting way of looking at knowledge and its place in the universe. I think before I get on to the issue of the reach of explanation and my quibble there, I just want you to talk a little bit about this notion of spaceship Earth, which I loved how you debunk this idea. There's this idea that the biosphere is in some way wonderfully hospitable for us and that if we built a colony on Mars or some other place in the solar system, we'd be in a fundamentally

different circumstance and a perpetually hostile one. And that is an impressive misconception of our actual situation. And you have a great quote where you say that the Earth no more provides us with a life support system than it supplies us with radio telescopes. So say a little more about that. Yes. So we evolved somewhere in East Africa in the Great Rift Valley. And that was an environment that was particularly suited to having us evolve. And life there was sheer hell for humans. Nasty, brutish, and short doesn't begin to describe how horrible it was.

But we transformed it. We, or rather, not actually our species, but the species that are some of our predecessor species, already changed their environment by inventing things like clothes, fire, and weapons, and thereby made their lives much better, still horrible by our present day standards. And then they moved into environments such as, as I also say in the book, such as Oxford where I am now, and it's December. And if I were here at this very location

with no technology, I would die in a matter of hours. And nothing I could do could prevent that. So you are already an astronaut. Very much so. Your condition is as precarious as the condition of those in a well-established colony on Mars that can take certain technological advances for granted. And there's no reason to think that future doesn't await us, barring some catastrophe placed in our way, whether of our own making or not. Yes. And also, there's another misconception there there which is related to that misconception of the earth being hospitable, which is the misconception that applying knowledge is effort. It's creating knowledge that is effort.

Applying knowledge is what we call automatism. It's automatic. As soon as somebody invented the idea of, for example, wearing clothes, from then on, the clothes automatically warmed them so long as they were wearing the clothes. It didn't require any more effort. Of course, there would have been things wrong with the original clothes, such as that they rotted or something, and then people invented ways of making better clothes. But at any particular stage of knowledge, having got the knowledge, the rest is automatic. And now we have invented things like mass production, unmanned factories, and so on. We take for granted that the water gets to us from the water supply without anyone having to carry it laboriously

on their head in pots. It doesn't require effort. It just requires the knowledge of how to install the automatic system. Much of our life support is automatic. And every time we invent a better way of life support, we then make it automatic. So the people on the moon, living on the moon in a lunar colony, to them, keeping the vacuum away will not be a thing they think about. They'll take that for granted. What they will be thinking about is new things, and the same on Mars and the same in deep space.

Right. Well, again, that's an incredibly hopeful vision of our possible future. And so thus far we've covered territory where I really don't have any significant doubts despite the fact that I pretended to have one with the ontological argument. So let's get to this notion of the reach of explanation, because you seem to believe that the reach of our explanations is unbounded, which is to say that anything that can be explained, either in practice or in principle, can be explained by us, which is to say human beings as we currently are. So you seem to be saying that we alone among all the Earth's species have achieved a kind of cognitive escape velocity,

and we're capable of understanding everything. And you contrast this view with what you call parochialism, which is a view that I have often expressed, and many scientists have expressed it. Max Tegmark was on my podcast a few podcasts back, and we more or less agreed about this thesis. And so the thesis of parochialism is just evolution hasn't designed us to fully understand the nature of reality. We're not, you know, either the very small, the very large, the very fast, the very old. These are not domains in which our intuitions about what is real or what is logically consistent have been tuned up in any way by evolution. And insofar as we've made progress here, it has been by a kind of happy accident. And it's an accident which gives us no reason to believe that we can, by dint of this accident,

travel as far as we might like across the horizon of what is knowable. So which is to say that if a super intelligent alien came to Earth for the purpose of explaining all that is knowable to us, he or she may make no more headway with us than you would if you were attempting to teach the principles of quantum computation to a chicken. And so I want you to talk about why that analogy doesn't run through, why why parochialism, this notion that we are, we just, we occupy this kind of cognitive niche that there is really no good evolutionary reason

to expect we can fully escape. Why that doesn't hold true. Yes, well, you actually made two or three different arguments there, all of which are wrong, so... Oh, nice. If you'd like to continue listening to this conversation, you'll need to subscribe at SamHarris.org. Once you do, you'll get access to all full-length episodes of the Making Sense podcast, along

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