... The anthropic principle says, the universe is the way it is because if it was any different, we wouldn't be here. The idea is that there's this big landscape with lots of universes in it, but the only one which can allow us to exist is the one with exactly the laws of physics that we see. It sounds like a flaky argument- and it is. It's a very flaky argument. Because it doesn't predict anything. It's a classic example of postdiction: its just saying, oh well, it has to be this way, because otherwise we wouldn't be here talking about it. There are many other logical flaws in the argument which I could point to, but the basic point is that this argument doesn't really get you anywhere. Its not predictive and it isn't testable. The anthropic principle, as it's currently being used, isn't really leading to any progress in the subject. Even worse than that, it is discouraging people from tackling the important questions, like the fact that string theory, as it is currently understood, is incomplete and needs to be extended to deal with the Big Bang. That's just such an obvious point, but at the moment surprisingly few people seem to appreciate it.
...For example, just to give a trivial example: if you ask, why is the gas in this room smoothly distributed, we need a physical theory to explain it. It wouldn't be helpful to say, well if it wasn't that way, there would be a big vacuum in part of the room and if I walked into it, I would die. If the distribution of gas wasn't completely uniform, we wouldn't last very long. That's the anthropic principle. But it's not the scientific explanation. The explanation is that molecules jangle around the room and when you understand their dynamics you understand that it's vastly more probable for them to settle down in a configuration where they're distributed nearly uniformly. It's nothing to do with the existence of people.