Complete Dialogue

[Editor’s note: After their formal presentations, Stephen Weinberg and John Polkinghorne engaged in a discussion of the issues of science and religion and design as well as responded to questions from the audience. Owen Gingerich moderated the discussion. The following is a transcript of their comments in which an effort has been made to retain their “voices” in written form.]

Weinberg: First, let me respond to John’s eloquent talk just on a few scientific issues which are not at the center of it but worth commenting on. I don’t agree that the two metaphysical approaches to quantum mechanics are the probabilistic theory of Bohr and the deterministic theory of Bohm. I share John’s view that I don’t think much of Bohm’s reworking of quantum mechanics. What I would refer to as an alternative to the probabilistic view of quantum mechanics is a deterministic view. After all quantum mechanics in its basic equations is completely deterministic. The Schrödinger Equation tells us that if we know the wave function in any instant, we know precisely what it is at any future instant and in fact there is no chaos as in Newtonian mechanics, because the equations are perfectly linear. The question always has been how to represent the observer in the deterministic evolution of the wave function. And this is a problem that is increasingly being solved although not yet completely solved. But that’s the opposition I would make between the modern deterministic view which sees the observer as part of the reality described by the wave function and Bohr’s view in which the observer was something separate.

Polkinghorne: That is another way of setting it up but you would agree that it is a metaphysical argument about ...

Weinberg: Yes, that’s right and ... it’s just I don’t think you should take Bohm, David Bohm, as the representative of ...

Polkinghorne: I just had two, I could ... but, of course, you are right.

Weinberg: Another question is about the fine-tuning. I, as I said in my talk, am not terribly impressed by the examples of fine-tuning of constants of nature that have been presented. To be a little bit more precise about the case of carbon, the energy levels of carbon, which is the most notorious example that’s always cited, there is an energy level that is 7.65 MeV above the ground state of carbon. If it was .06 of an MeV higher, then carbon production would be greatly diminished and there would be much less chance of life forming. That looks like a 1% fine-tuning of the constants of nature. If the energy level were lower, then there would be even more carbon produced. But it is striking that it could not be more than a percent higher. However, as has been realized subsequently after this “fine-tuning” was pointed out, you should really measure the energy level not above the ground state of carbon but above the state of the nucleus Beryllium 8 (⁸Be) plus a helium nucleus. And it is only .28 MeV above that. In other words, the fine-tuning is not 1% but it’s something like 25%. So, it’s not very impressive fine-tuning at all. I’m not saying that none of these examples of fine-tuning will survive or that we won’t discover others. I’m also not saying that the many universe picture has been established. These are open questions. Are the constants of nature remarkably well adjusted to allow for the presence of life? We don’t really know. And can they be explained by having many sub-universes? We don’t really know that either. And indeed at any moment we may get evidence of a supernatural supervisor of the universe. I mean suddenly in this auditorium a flaming sword may come and strike me for my impiety, and then we will know the answer.

Polkinghorne: Actually, we won’t. But that’s by the way.

Weinberg: I don’t agree that this is a metaphysical question. I think the question of - if there are these many terms in the wave function as Coleman describes or many separate big bangs as Linde would have it, this is something that will appear in our scientific theories. It hasn’t yet. We don’t know this for sure. It has appeared as a possibility but it is not something that’s going to remain a matter of metaphysical choice. Either our theories will show us that this is the case or they will not. And it will not be a matter of personal taste. At this moment the question is open.

The question John raised - John has raised this before in his writings and I thought I had answered it in my talk, but let me underline the answer I offered. He said, “Why is it that we are so fortunate to be able to do quantum mechanics and do mathematics? Is it really necessary from evolution that we should be able to do this?” And I would answer; no, it is not, that we are able to have such abstract thoughts and to be able to have the leisure to sit around talking about it. It may be, as I explained, that in the great majority of planets where life arises and evolves only that measure of intelligence evolves which is strictly necessary for breeding and eating. However, those animals are not discussing the issue and the fact that we are discussing the issue creates a bias and naturally the people who are discussing the issue have intelligence and the leisure to discuss it.

Now, John makes a big point that science is not everything. I think this is really - the points I have covered so far, I think, are minor points. The big point, “Science is not everything.” There is, in addition to physics - there is metaphysics. I agree, but I do look differently at the examples he gave.

It is certainly true that scientists are helped in their work by non-rational processes involving an aesthetic sense of beauty, which is very well developed among mathematicians. Mathematics is the science of order and they see order in an abstract inner directed way, which often turns out, quite spookily, to be relevant to the real world. And this poses a problem, how to understand this. And I would try to explain it as the sort of learning that goes on whenever one has long experience - one learns things that one can not express in words. Our long experience is the many centuries of experience of scientific work in which we have learned what sort of thing is beautiful, we’ve learned what sort of mathematics is possible. Not all forms of order are possible. And we’ve learned what sort of ideas might be relevant to the real world. I think that’s what we mean by beauty and, in fact, our sense of beauty has changed.

Today, beauty based on symmetry, on invariance under some group of transformations of change of point of view, is regarded as a highly beautiful part of a theory. Something you would be proud to base a theory on. At the beginning of this century that wasn’t true; in fact, Lorenz criticized Einstein for basing his special theory of relativity on a principle of symmetry which is not something that one should take as a starting point of a physical theory. So, in this sense, I think, we are in the grip of a learning machine which is gradually beating into us a sense of beauty which is a very important part of the work of science.

Finally though, I must admit science isn’t everything. It certainly isn’t. There are things that are outside the scope of science and which are still terribly important to human beings. There is metaphysics of a sort that goes beyond the kind of learning processes I mentioned. But there is also aesthetics and morality. It seems to me that there’s an unbridgeable gulf between statements with the word “is” and statements with the word “ought.” There is no way a scientist [science] can ever tell you how you ought to behave. It may tell you, if you have some fundamental moral principles, how you can satisfy them, how you can bring about what you take as a desired goal. But it can never tell you what your goals ought to be.

There is a moral order. It is wrong to torture children. And the reason it is wrong to torture children is because I say so. And I don’t mean much more than that. I mean that not only I say so, John says so, probably most of us say so but it is not a moral order out there. It is something we impose and bully for us. And in this respect I think religion is no better. Because, think about it, suppose there were a designer, suppose you knew that the universe had been created by a designer who watched our progress and intervened and behaved very much like the god of the Old or the New Testament. That has no moral implications. That god may set down moral principles which are wrong. Wrong from what point of view? Our own point of view. What other point of view could there be? And indeed, that is what I would say is the case. I don’t believe in torturing children but god apparently, according to many religious faiths, believes that children, who were not baptized or when they get older who do not accept god or who do not come to him through Christ or through the Koran, are subject to eternal damnation. I think that even those who believe in a god still have the responsibility to answer the question, “What is right?” And they have to answer it for themselves and, if they accept the morality provided by god, that is their choice, so that they, like the atheist scientist, have to make a free choice of moral behavior which is not dictated by a theory of the universe religious or scientific. Thank you.

Polkinghorne: I want to make a few comments on that, if I may. This question of the nature of morality is a very important issue. I don’t think we just make it up. I don’t think that Steve and I make up one sort of morality and Hitler and Stalin make up another sort of morality. On what basis does Steve say, “Bully for us,” and deny them. There has to be something that transcends, I think, human construction there otherwise these senses of value don’t somehow function the way they do.

Theology does make progress, very slowly. That’s one of the reasons why I swapped out of physics and into theology. It is a more stately subject. But in the 19th century Christians first began to question and have continued to question and dispose of the question really, most of them anyway, that the god of love would condemn people to infinite torment for finite transgressions. Our picture of Hell - that doesn’t mean that Hell’s gone, but Hell is no longer thought of as a place of torment into which an angry God has cast people, it is thought of as colored gray rather than red, as a place of boredom to which people have condemned themselves by their own choice of excluding the divine life. That’s just a little point on Hell and I think that is actual progress in theology to have reached that.

But I think the fundamental difference between you in me is this. We both want to take human persons seriously but we take them seriously in radically different ways. You see human persons as constructing a world of meaning which is a sort of oasis of meaning in a vast desert of a hostile and meaningless universe. I see us not constructing meaning - of course, there is a constructive element in it - but I see us discovering meaning also and that is for me a clue to the nature of reality more generally. It is not an internal good of the human community, of sections of the human community; it’s a perception of the real. And therefore, I see that as a clue that we are not defiant, heretically defiant, inhabitants of an island of meaning in an ocean of meaninglessness but that in fact the world has a meaning that extends beyond us. That is the basic difference between us, I think.

Weinberg: Well, I don’t disagree with that and I don’t disagree with your characterization. If, in fact, there is out there built into the structure of the universe an objective meaning, an objective moral order, that would be really quite wonderful. And perhaps part of my passion about this arises from regret that it isn’t true. But, if it isn’t true, then surely it’s better that we not kid ourselves into thinking that it is. It’s better that we salvage what we can from at least the satisfaction of creating some meaning around us.

Polkinghorne: I would say I would agree with you that if it isn’t true then it is better that we know it. The central religious question is the question of truth. I mean religion can do all sorts of things for you, console you in life and at the approach of death, but it can’t really do any of those things unless it’s actually true. Not in some knock down sense, because, of course, the divine reality will always exceed our finite thoughts. But if there isn’t a benevolent divine will or purpose behind the world, it is better for us to know that than to live in a sort of happy illusion. I don’t see religion as a way of keeping our spirits up and keeping us through life in a happy illusion in that way.

Weinberg: Yes, in this respect I think John and I represent - we are probably the wrong people to be debating because we represent what must be in today’s world a minority. Just speaking to people in general I find that their - many people claim to be religious and when you ask them what they believe in you find that they have no beliefs to speak of. I love a quote that I have used by Susan Sontag that it’s “piety without content.” I spoke to a Buddhist a while ago and asked, “So, you really believe in reincarnation?” And they said no, they didn’t think they believed in reincarnation. And I couldn’t imagine what it meant to be a Buddhist and not to believe in reincarnation but for them Buddhism was just a flag rather than a belief. So, in this respect John and I are not the right people to argue.

Questions

Gingerich: Steve Weinberg, what meaning if any do you see in the fact that many scientists see their own work, solutions to problems, as coming from outside themselves even having a religious dimension, perhaps?

Weinberg: I don’t think that’s true. In my experience, just talking to my fellow physicists at lunch, I think most of them have not only no religious faith but no interest in the issue. I am a little unusual in being interested in the question. I think again there is a selection effect. Scientists who do talk about supernatural influences on their work are the ones who are likely to get published and win prizes endowed by Mr. Templeton. But, I think the public is getting a rather misleading view. I think most scientists are not atheists to speak of because they don’t think about it enough to be atheists. There are scientists who are quite religious, my friend here and others, but I think they are thin on the ground.

Polkinghorne: Can I just briefly comment on that? I mean this is anecdote swapping. My impression is somewhat different. I certainly agree that the majority of scientists are not religious believers in some traditional sense. I think that the majority in my view, thinking of my friends, are people who can neither take religion or throw it away. They are slightly wistful in relation to religion. They’d like to think there is a deeper meaning and purpose behind things. But they’re wary of religion. They are wary of religion because they think religion involves accepting things on authority which is what someone said this morning, I think, in a question. I want to always say that religious belief isn’t shutting your eyes, gritting your teeth, believing six impossible things before breakfast because the Bible tells you that’s what you gotta do. It is a search for motivated belief. A difficult search and different people will reach different conclusions about it. But you don’t have to commit intellectual suicide to be a religious believer; otherwise I wouldn’t be one.

Gingerich: The questions which have come in are quite interesting but I think many of them are what you would consider simply debating points and not genuine questions. But here is one for both of you. What is the point of continuing to live in a universe that has no ultimate purpose? That’s for you, Steve.

Weinberg: Well, if you don’t see the point then, too bad for you. I feel there is a point. How can I say it? There’s nothing in science that says we should look at life as not worth living any more than there is something that tells what there is about life that is worth living. It is left as an open question for us to decide on any grounds we like. And for me I enjoy life and there are things I value very much about being alive and that’s the point it has. I remember in the preface of one of his plays, I think it was Heartbreak House, George Bernard Shaw said, “Darwin has knocked centuries of dusty theology out of the room and now we don’t have any of that anymore but a the same time he has knocked out morality. And now because of Darwin’s work there is no basis of any moral principle.” I disagree. I don’t think Shaw was right about that. I think Darwin perhaps took away the idea that there was a supernatural plan which imposes a moral order - not only Darwin but science in general - but it did not say that we must behave immorally. We are left to make moral choices or not and we are free to make them. And, in fact, not only to make moral choices for ourselves but for others just as we would condemn someone else who tortured children. We’re free to find point and to make moral choices. We don’t get them from an objective supernatural world order.

Polkinghorne: There was a German atheist philosopher, Max Horkheimer, who said there was a deep longing in the human heart that the murderer should not triumph over his innocent victim. And some of us entertain that hope that the murderer will not ultimately triumph. But those that can’t entertain that hope and who live a sort of, if I might say so, a life of austere nobility in the face of a hostile world, I think that is a very - I think it is mistaken but that it is an admirable position to hold, if I may say so.

Gingerich: Here is a question for you, John. Could you imagine an ultimate argument that God is not existent? If we cannot refute this mode of explanation, then it is just a matter of belief. But how can we be sure or convinced that it is not just wishful thinking?

Polkinghorne: That’s a very interesting question. I think that certainty, in the sense of logical proof, is a pretty spare quantity. There isn’t too much of it around. I mean, Kurt Gödel has told us that even mathematics has its aporia, as the theologians say, its uncertainties. And I think it is also the case that there is a sort of complementary relationship between things that are really interesting and things that can be proved. So, I think we shouldn’t worry about proof and certainty.

That doesn’t mean that anything goes. We should search for motivated beliefs. But I think this is true of both science and religion and everything that lies between them, we will attain beliefs that are motivated but will never be certain. I think one of the best books on the philosophy of science written in the 20th century is Michael Polanyi’s book, Personal Knowledge. Polanyi was a distinguished physical chemist before he became a philosopher. That means he’s been not very well accepted in the philosophical community, I am afraid to say. He wrote this book, he said - and he was talking in relation to his scientific beliefs - how I can hold to what I believe to be true knowing that it might be false. And that is the human condition, I think, whether it is in science or religion or other things. So, I think we shouldn’t get fixated upon certainty. I don’t think you can prove God exists; I don’t think you can prove God does not exist.

Gingerich: Steve, you stated that there is a mysterious realm that science will never explain and that a similar statement is true about religion. What do you see as the nature of this mysterious realm? How is it different from your conception of a religious realm?

Weinberg: Well, the realm I refer to is just the - I do believe we will find, I am not certain about this, but I do believe that sometime in the next century or so we’re going to find that all our physical theories converge to a fundamental theory, maybe something like the string theories that people are talking about today, maybe something deeper, from which in principle all other scientific generalizations that don’t simply rely on historical accidents can be inferred. The mystery will be: why is that true? It will be something very specific, very crystallized into a clear scientific statement. We will then wonder why is it true? As I said there may be a chance of answering the question why it’s not slightly different, but we probably will not ever get the answer why the truth is not totally different.

There is the possibility that we may be able to show that there is no other logically consistent theory which would allow a rich enough universe to allow for people to be raising the issue. That doesn’t completely satisfy me but it may give some satisfaction. I mean when, for instance, you look for alternatives to quantum mechanics you think of Newtonian mechanics which don’t allow for atoms and I can hardly imagine how life could evolve in a purely Newtonian world.

But, on the other hand, the religious mystery is, well, a mystery of whether any of it is true which will always be with us because there’ll never be any - unless the flaming sword descends, unless miracles start happening again in a reproducible way that they haven’t - there’ll never be any way of being certain about religion and the truth as the religious thinker finds it will always be flexible, it will always be something that can be - that can vary indefinitely.

Polkinghorne: May I just say that, God forbid, if a flaming sword were to come and decapitate Steve before our very eyes that would pose a very big theological problem. Because that would be the capricious act of a magical, vengeful god and that’s not the God of my belief. You see the problem of miracles ...

Weinberg: It is the god, however, of your religious tradition.

Polkinghorne: Ha. I wouldn’t say that the religious tradition is unsullied with that belief but it’s certainly not the sole element, strand within that belief. The problem of miracles is the problem of divine consistency. God is not capricious but God is not condemned equally to dreary uniformity.

Weinberg: Well, it would pose not only a theological problem but a janitorial problem.

Gingerich: Steve, here’s a final question for you. You completely reject any notion of a divine designer, but on what basis beyond faith can you justify the idea of multiple universes being more valid?

Weinberg: Oh, I thought I had answered that but I would be happy to say it again. I don’t maintain that that idea is true. I mean, that is a possibility that has emerged and it remains a possibility. When I become convinced of it’s truth, it will be because the equations of physics that unify the various forces - quantum mechanics, relativity, all that - have that as a consequence. It won’t be an act of faith. It will be a deduction from laws which we, unfortunately, at present don’t know. Now you may say that it is an act of faith because we will not be able to observe these other Big Bangs, or these other terms in the wave function. But that’s the fate that science has been in for a long time. We don’t really observe quarks and we never will see the track of a quark. And yet we believe in quarks because the theories that have quarks in them work. And in the same way, if we come to that - and we have not yet come to that - we will believe in these other Big Bangs or these other terms in the wave function because the theories in which they appear work.

Gingerich: ... Ladies and gentlemen, let me just remind you ... that this is the very room in which in April of 1920 the very famous Shapley/Curtis debate on the scale of the universe took place; a debate that has gone down in astronomical lore ever sense. And I think you have been very lucky to have been present at this debate today which I suspect will also assume mythic proportions.

Contributed by: Sir John Polkinghorne and Steven Weinberg