Imagine that the
word universe is actually a
misnomer in that there is not just one of them. Instead there are an incredibly or even
infinite number of universes which all reside in a "
multiverse". Scientists in our particular
universe or our section of the
multiverse discover
M-Theory - the overarching
structure of
Superstring Theory (commonly known as "
String Theory") -, and begin to wonder why it is that
life can exist in our particular
manifestation of
string theory*.
But could it all actually just be that in order to ask such a question the proper requirements for life must already exist and therefore the question is basically invalid? That in these infinities of universes the majority go without developing intelligent life simple because the conditions are not proper? But, in our universe, life developed and becamse intelligent enough (some my argue with me here...), at least for scientific inquiry.
We exist because we can. There is no other reason. Had intelligent life been so that it should develop in a different environment then the beings in that universe would now be the ones asking the questions and not us.
This is the principle but forth by various physicists over the years. Stephen Hawking discusses it as does Brian Greene The Elegant Universe. It may be that this is the always-present easy out. It may be that there is no good answer for the whys. I think we have to just search, because there's no way to know what's really out there.
* There are values which could be different in a different universe; for example, the weight of protons or the charge of electrons. String theory hopes to discover exactly "why" the values which exist here are what they are, but the anthropic principle might make the search pointless.