To ask why there is something rather than nothing seems to assume on some level that it's less natural for the universe to exist than to not exist. It also assumes that some kind of existential inertia means that there will continue to be something rather than nothing.
This second assumption at least is not universal to humans, and is covered by Robert Nozick in the most effective treatment of this question yet. The Inuit believe that if hunting ceases, even for an instant, the universe will end. Several religious traditions hold that if at any given moment, at least one person somewhere is not copying their holy text, reality will sink back into chaos. These examples are interesting but are probably better explained as cultural technologies to keep people motivated in performing important activities, than as insightful cosmogonies.
Another question is whether it is clearly meaningful to ask counterfactuals about the fact of existence itself - whether existence had to exist - versus finite entities within existence. It is clearer that the pine tree outside my window, or you, might not have existed. In this way existence as a whole, the capacity for things to exist, is qualitatively different than a pine tree.
Changing gears to the ever-popular deep mystery, is it meaningful to talk about a universe that has no consciousness? Is self-awareness, a part of the universe experientially looping back on itself, necessary for existence? There is an intuition (which I share) that questions about necessity of existence and of subjective experience are getting at the same things.
Help Me Choose Posts for My Next Book :-)
19 hours ago