Why is the world the way it is? Presumably there are a whole raft of possible worlds, so why is this one actual? It's a weird question, but it seems a reasonable one to ask. I feel like this is a fact in need of explanation. (Does anyone disagree?) But it's hard to imagine what the explanation might be. Here are a few possibilities which spring to mind:
1) Brute chance. A different world could have been actualized, but it simply happens that this one was instead, for no particular reason. (That's an explanation of sorts, albeit a fairly unsatisfying one.)
2) Design. Someone (call them 'God') had the option of which world to make actual, and chose this one. (Why? You'll have to ask her.) [Regress: why does God exist? I assume most theists will then appeal to the next explanation...]
3) Necessity. There are two variations on this theme:
(a) Our world is the only genuinely possible world [are we to take this as a brute modal fact?]. When we think that there are other ways the world could have been, e.g. with different physical laws, we are simply mistaken.
(b) Modal realism: all possible worlds are equally real, and necessarily existing, and so this world in particular could not have failed to exist as it does. (This leaves open the locative question of why we find ourselves in this world rather than some other. But that's a separate issue, and not uniquely troubling here. For now, I'm more concerned about the ontological question of why our world exists.)
Are there any other options? Which is the best explanation?