Anthropic Principles

Carter’s strong anthropic principle says this about conditions in any cosmic region you decide to call “a universe”, while his weak anthropic principle says the same thing about conditions in anything you prefer to call a spatiotemporal locality. Inevitably, though, one speaker’s “large spatiotemporal locality” is another speaker’s “universe”, for there are no firm rules for using these words. The point to notice is that neither Carter’s weak anthropic principle nor his strong anthropic principle has anything to do with divine design. These principles concern observational selection effects, period. When reminding us, with his strong anthropic principle, that the universe in which we find ourselves must (since we observers are in it, aren’t we?) be a universe whose properties are not totally hostile to life and to intelligence, Carter has never meant that this universe was forced to be of a kind which would permit intelligent life to evolve, let alone that it had been positively compelled to contain intelligent living beings. He has always accepted that a great deal of randomness might enter into whether a universe developed life - permitting properties, and if it did, then whether living things, intelligent or otherwise, would actually evolve in it.

I ought to make clear that Carter has himself written so little about this area that he has now largely lost control of what the term “anthropic principle” means. I sometimes get the impression that most people use the phrase “believing in the anthropic principle” to mean something like “believing in divine design”; and, sure enough, when sufficiently many folk use words in a particular fashion, then that fashion can become right. Still, I recommend using the term “anthropic principle” in the way that Brandon Carter outlined.

Instead of confusing Carter’s observational selection with divine selection, otherwise known as divine design, might we not combine these two things? Imagine God creating hugely many universes, the general properties of each universe being settled by random processes at early instants. Suppose that the likely outcome of such random processes would be that only a tiny proportion of the universes had properties permitting life to evolve. God could still be certain that life would arrive in many places if he created sufficiently many universes - perhaps infinitely many. And although it would now be observational selection, not divine selection, which guaranteed that intelligent beings found that their universes had properties of life - permitting kinds, God might still be counted not merely as a creator but also as a designer since he had at least ensured that the fundamental laws obeyed by all the various universes were laws leading living beings to evolve in some of them. Why not think along these lines?

I suspect that they would be unsatisfactory lines. Yes, a deity interested in producing good states of affairs might be expected to create infinitely many universes, for why be satisfied with creating only fifty - seven, or only thirty million? However, it could seem bizarre to imagine that this deity would create any universe which he knew in advance would develop in a fashion totally hostile to intelligent life. And he could of course know in advance whether a universe would become totally hostile if this depended on physical processes that were only partially controlled by fundamental laws since these laws, for instance ones of quantum physics, failed to dictate precisely what would happen, so that the deity himself had to decide this when exerting his power of conservation, of keeping things in existence while at the same time changing them slightly. Remember, divine conservation, the preservation of the existence of things, without which they would at once vanish, is very traditional theology. And theologians are not such fools as to fancy that “conservation” here means “preservation in a totally unaltered state” so that nothing ever changes.

Contributed by: Dr. John Leslie