video
Topic Series
John Leslie
Sara Imari Walker on Physics, Emergence, and Life on Other Planets
Greg Epstein on Technology, Morality, and Non-Religion
David Papineau on Consciousness, Physics, & the Mind-Body Problem
Or Graur on the Big Bang and the Physics of Galaxies
Ned Block on Perception, Cognition, and Consciousness
Brian Swimme on Consciousness, Cultural Evolution, and the Noosphere
- Robert Lawrence Kuhn
- John, in trying to understand existence, I'm told by various people—philosophers, physicists—that to think about nonexistence is absurd. In other words, why worry? The thing that upsets me and I think about is just a non-issue and totally dismissed. I feel – I – I feel like I'm stupid.
- John Leslie
- Well, you'll find a lot of type people saying precisely that, that there's some sort of contradiction in blankness, that if we knew enough logic we could say that there had to be a universe. How do you actually refute them? Only by going and looking at some very complicated arguments. Suppose you take the argument, which I like, that things could vanish one by one until the last one went. You'd have some people saying, well they could vanish one by one, but with the last one going then all the laws of mathematics would have to go because they depend on countable things. Even if you have a single thing, you can always split it up into bits and say two and two make four by the bits, but if the last one goes, poof, mathematics goes. And it's ridiculous to say that mathematics, mathematical truths, wouldn't keep on being true. Therefore, the last thing couldn't go, and then some people think that there's a mind behind the universe.
- Robert Lawrence Kuhn
- God, or something. How does – how does that work, that a blank is absurd?
- John Leslie
- Well some people would say that a blank is absurd because you can't imagine it. And others would try to give a bit more force to this by saying reality is essentially mental and there wouldn't be anything mental in a blank, and therefore blank can't exist. That was argued by the idealist philosophers who took after Hagel. Another way is to say that physics, in some way, makes a blank absurd.
- Robert Lawrence Kuhn
- Why is that?
- John Leslie
- Well, I would tend to react in the same way. How can they say that? But recent pronouncements by Stephen Hawking, he says that logic, or he seems to say that logic can explain the existence of the universe. And if we are to take that seriously, that would mean that there's some sort of contradiction in a blank.
- Robert Lawrence Kuhn
- A blank meaning absolutely nothing at all?
- John Leslie
- Absolutely nothing, nothing existent. I want to say that even if there was nothing existent there could be all sorts of facts, truths, and so on. And Stephen Hawking would seem to be saying that some of those facts, truths, truths about quantum physics, and they make a blank unstable and make it necessary that a universe exists. Again, some people would say that there's no essential difference between the mere possibility of something and something being real somewhere.
- Robert Lawrence Kuhn
- Now how does that work? That sounds very strange. I mean I can think of a possibility of a unicorn, or a possibility of a universe where everyone looked like me. I mean, those are possible universes.
- John Leslie
- Well there is one extremely clever philosopher, recently died off, David Lewis, who thinks that there are universes with unicorns and there are, indeed, universes where everybody looks exactly like you.
- Robert Lawrence Kuhn
- I wouldn't want to live there myself.
- John Leslie
- Lewis's view is that all possibles exists somewhere, it's just they don't exist in our world. They–
- Robert Lawrence Kuhn
- And that's why a blank, an utter nothing, is absurd?
- John Leslie
- It's absurd because you can't get rid of possibilities; I think that's correct. But he says he can't think of possibilities as real as genuine possibilities unless they genuinely exist somewhere. And Lewis is a very, very clever man. I think his system gets into problems, but he's clever and he thinks the problems go away.
- Robert Lawrence Kuhn
- When Hawking talks about that, a blank or nothing would be absurd because of the laws of physics, that's not nothing. The laws of physics are not nothing, even though the laws of physics would have nothing – be an instability and, therefore, something would have to arise. So why is that an absurdity? Why does that mean that nothing would be an absurdity?
- John Leslie
- Well, first, as I said, there's nothing clear in this area at all. Somebody as clever as Einstein suggested that it might have been that God had no choice as to what to create. There could be just a single coherent cosmic possibility. And you might see Hawking as doing the sort of thing that Einstein wanted to do and adding a little more structure to it. Now this horrifies most philosophers. Most philosophers would say they can easily think of worlds which are completely different from our world, which obeyed laws of physics which are completely different from the ones we see, or which are so quite chaotic that they obey no laws at all. This would be the sounded philosophical view. And it's tempting to read Hawking as not meaning what he seems to say. He says in – he and Mlodinow say in the book they recently put out, The Grand Design, that abstract considerations of logic could explain why the universe exists. Now, this might mean simply that the laws of physics are such that if you tried to bend them slightly, they would break completely.
- Robert Lawrence Kuhn
- And therefore that's the only way that it could work so–
- John Leslie
- The only way that laws, even vaguely like this could work, would be that the laws would be exactly like this. That could be what they're saying. But it could be that they are believing that ultimately the laws of physics are somehow, in the end, dictated by the laws of logic. And as a good philosopher, I say this is nonsense, but there are a lot of physicists who are taking it seriously. And Hawking is a very clever guy. So maybe there's something there, or maybe there's something in the view that the laws of physics could exist even if the universe weren't there. That I take more seriously than the view that there would be a contradiction in the universe not being there.
- Robert Lawrence Kuhn
- Sure. Sure.
- John Leslie
- I think that the idea that the laws don't have to depend on the universe being there that should be taken seriously, even though I, myself, don't believe it.
- Robert Lawrence Kuhn
- Alright. So looking at this at the whole, from the physical point of view, from the philosophical point of view, from this plentitude of worlds point of view, how do you analyze, what is your view of the answer to existence being that nonexistence is absurd?
- John Leslie
- Well, my view is that that doesn't work. That nonexistence would have no absurdity in that you could image things vanishing one by one and then the last thing goes, and there you have nonexistence. This is an argument which is being developed these days by some very good philosophers. Also, I, myself, think that there's a necessity behind the existence of the universe, which you wouldn't be absurd to deny this necessity. There'd be a conflict with the nature of necessity if the universe weren't here, but it's not a logical conflict. Talking about a blank isn't like talking about a round square, or what philosophers always talk about, a married bachelor. Married bachelors and round squares, they're absolutely impossible. We can see that there's a contradiction there. There's no contradiction, which will ever be seen in the same way in blankness. That's my own take on it.