I would guess that within the next few decades or centuries, mainstream philosophy will reach one of two conclusions here:
- No fact or cycle of facts can be meaningfully self-explaining, and so the Big Why is provably unanswerable.
- The Big Why is rendered fundamentally incoherent by its self-contradictory assumption that there pre-exists a tendency toward non-existence.
If we don't ever know the answer, here is a fundamentally unverifiable answer that may nevertheless satisfy some people:
Nothing exists except logical possibility, which necessarily exists, and our perception of material existence is an epiphenomenon of our being logical subcomponents of a logically possible universe.
Consider gliders in Conway's game of Life. Even if nobody ever wrote down the rules of Life, gliders would still be a logical consequent of certain possible configurations of the logically possible game of Life. It has been proven that Life is rich enough to instantiate a Turing machine, which are of course known to be able to compute anything computable. So if mind is computable, consider a configuration of Life that instantiates a Turing machine that instantiates some mind.
Consider the particular Life configuration in which that mind eventually comes to ask itself "why is there something instead of nothing?". Even if in our universe no such Life configuration is ever instantiated, that particular configuration would still be logically possible, and the asking of the Big Why would still be a virtual event in the logically possible universe of that Life configuration. The epiphenomenal quality of that event for that logically possible mind would surely be the same, regardless of whether our universe ever actually ran that Life configuration. So the answer to that mind's Big Why would be: because your existence is logically possible.
So pop up a level, and consider that you are that mind, and that your universe too is just a (highly complex) logically possible state machine. In that case, the answer to your Big Why would be the same.
Note that, while the Life thought experiment depends on mind being computable, the logically possible universe (LPU) thought experiment only assumes that our universe could be considered as a logically possible sequence of (not necessarily finitely describable) universe-states. The LPU hypothesis also depends on the thesis that physicalism is right and that qualia and consciousness are epiphenomena. The LPU hypothesis is of course unparsimonious (sort of like the many-worlds interpretation of quantum theory), but parsimony is perhaps inconsistent with *any* answer to the Big Why. The LPU hypothesis is incompatible with strong free will (which itself may be incoherent), but is compatible with weak free will (perhaps only if we assume there are rules governing the transitions among universe-states).
The idea that the world might be a dream is of course not new. But I don't recall ever hearing that the world might be just a logically possible dream for which no dreamer exists.
[Posted on talk.philosophy.misc on 2001-01-12.]