Valentine's Day theology
A friend once told me she thought I wanted to prove the existence of God. She meant that I was too ambitious in my work, but what the heck, let’s talk about the existence of God. Warning! This is amateur theology. I bet there are professionals who have thought this all through very carefully. I am just too lazy to read them.
The best argument for God is probably no different from what it was back in the 18th century: the universe seems well-designed to sustain life. As Robert Boyle put it: “a machine immense, beautiful, well contrived... cannot have been the effect of mere chance”. The key exhibit for this view back then was the existence of complex life forms. Even a sceptic like Gibbon could write:
... the enthusiast who entered the dome of St. Sophia might be tempted to suppose that it was the residence, or even the workmanship, of the Deity. Yet how dull is the artifice, how insignificant is the labour, if it be compared with the formation of the vilest insect that crawls upon the surface of the temple!
This argument took a body blow when Darwin showed that life’s complexity could be the result of evolution. But although evolution explains life, it still seems surprising that the universe contains places where evolution can arise. It can’t arise everywhere: life could never evolve at the centre of the sun, because the temperature would destroy it.
Is the universe really surprisingly capable of sustaining life? To answer this we need to think what the set of possible universes could be. A good start is the set of universes that can be described by maths. For example, here are some possible universes: a two dimensional space, with no time, in which points are either “solid” or “empty” (or “there” or “not there”, or whatever). These aren’t very interesting universes for a biologist – they certainly couldn’t sustain life. They are the universes mathematicians draw on graph paper: subsets of the 2D plane.
Still, even these simple universes have some interesting variation. One such 2D universe has “solid” points wherever x = 0, and nowhere else. This universe is highly predictable. If you needed to fly your spaceship around this universe, without hitting a solid point, you’d only need to avoid the line going through the origin. The rule “don’t go near the x = 0 line” would work everywhere. You could learn it in one place, and it would apply everywhere else.
Another of these 2D universes just has random points being “solid”. Maybe every point has a 1% chance of being solid, independently of all the other points. If you tried to navigate this universe, you’d be screwed. No matter what you learned about your local area, it wouldn’t help you navigate anywhere else. Sooner or later, your spaceship would run into a rock.
The first universe is law-like. The second universe is not. Evolved life requires a law-like universe, because evolution lets organisms adapt to their environment. If the environment changes unpredictably, then that adaption will be useless. And, guess what, our universe is highly law-like. (Drop an apple from your hand: it falls downward. Now drop it again: a miracle! It falls again, in the same direction.)
Is our universe surprisingly law-like? It seems to be. Among the possible 2D graph-paper universes, the vast majority are not lawlike at all: they can’t be described in a simple rule like “solid wherever x = 0”. (There may be some subtle issues of information theory here, but I’ll just ignore them and assume I’m right.)
If so, then it would be surprising for our universe to arise by chance. It would make more sense for it to be created by a designer who wanted life to arise. (There are subtle issues about the concept of probability here, but guess what I’ll do.)
This view has some counter-arguments. One is that life only arises in a few tiny corners of space – maybe only in one specific planet, if that’s how you resolve the Fermi Paradox. So perhaps even a random universe could have tiny, predictable corners where life emerges?
But this counter-argument assumes the whole machinery of space and time. It imagines a set of universes where most of space-time is unpredictable, or otherwise hostile to life, but a few parts of space-time can sustain life. But space and time themselves are features of our universe that could be different. Here’s a set of universes that’s even more minimal than the graph paper one. These universes are a collection of points which are either “solid” or empty. Here’s a universe with 4 points: {1, 1, 0, 1}. And another: {0, 1, 1, 0}. But there’s no distance between these points. They just exist. These are “conceivable universes”. You can’t fly around them, but you can reason about them (for example, the first universe has more solid points than the second one). Put it another way: the existence of space-time itself is part of the predictability of our universe. I walk to the shops, and I always get there, passing through each point along the way. I never get transported to Australia or Mars!
Another counter-argument is the anthropic principle. This is the idea that any universe we observe has to be complex enough to sustain life, because otherwise we couldn’t be alive to observe it. So, although among all possible universes, being life-sustaining may be very rare, all observable universes are life-sustaining.
This is a subtle point. One simple response is that, yes, it’s not surprising that the universe is life-sustaining given that we observe it, but we should still be surprised that we do observe it. Here is a nice analogy, which I actually did get from a theological article. Suppose that, during the Mexican revolution, you are captured by the other side. The revolution being what it is, you are sentenced to the firing squad. (Curse you, General Huerta!) You are blindfolded. You hear the order to fire. In terror you lose consciousness. Yet, a while later, you wake up. You feel sun on your face, and someone is shaking your shoulder.
Now, should you be surprised? A supporter of the anthropic principle might argue “of course you shouldn’t be surprised. Given that you’re around to observe these events, naturally you must have survived somehow.” Well, yes, but I think that you still should be surprised and need an explanation of what happened. If that analogy holds, then it’s still surprising that we are here to observe this life-friendly universe.
These arguments make me think that creation by Divine intelligence is still a reasonable hypothesis for the existence of the universe. Of course, they don’t say anything about what this intelligence might be, what He thinks He’s doing, what His attitude is to us, or whether He keeps kosher.
Happy Valentine’s Day!
I don't get your response to the sampling argument. What is the sample space? I can understand what the broad possibilities for the fire squad scenario are. But, as you yourself illustrate above, the number and variety of possible universes is unfathomable.
One way to go about this discussion is to make the observation that our notion of what god is evolves the more we know. Things that were once in the deity domain (from thunderstorms to dreams) consistently move as new understanding come along. If you want to call the set of universes God, that's fine. One thing, I think, is clear. Any existing human notion of a god that has any relevance to ethics or human structures is highly unlikely. So what is the use of using this loaded term?