Anthropic Principle

The Anthropic Principle

In the early 1970s, Brandon Carter stated what he called "the anthropic principle": that what we can expect to observe "must be restricted by the conditions necessary for our presence as observers" (Leslie ed. 1990). Carter's word "anthropic" was intended as applying to intelligent beings in general. The "weak" version of his principle covered the spatiotemporal districts in which observers found themselves, while its "strong" version covered their universes, but the distinction between spatiotemporal districts and universes, and hence between the weak principle and the strong, could not always be made firmly: one writer's "universe" could sometimes be another's "gigantic district". Moreover, the necessity involved was never -- not even in the case of the "strong anthropic principle" -- a matter of saying that some factor, for instance God, had made our universe utterly fated to be intelligent-life-permitting, let alone intelligent-life-containing. However, all these points have often been misunderstood and, at least when it comes to stating what words mean, errors regularly repeated can cease to be errors. Has Carter therefore lost all right to determine what "anthropic principle" and "strong anthropic principle" really mean? No, he has not, for his suggestion that observership's prerequisites might set up observational selection effects is of such importance. Remember, it could throw light on any observed fine tuning without introducing God. Everything is thrust into confusion when people say that belief in God "is supported by the anthropic principle", meaning simply that they believe in fine tuning and think God can explain it. As enunciated by Carter , the anthropic principle does not so much as mention fine tuning.

Being aware of possible "anthropic" observational selection effects can encourage one set of expectations, and belief in God another set. If suspecting that Carter's anthropic principle has practical importance, you will be readier to believe (i) that there exist multiple universes and (ii) that