Full Idea
It is necessary that there be something rather than nothing because it is necessarily contingent that there is something rather than something else.
Gist of Idea
It is necessarily contingent that there is one thing rather than another - so something must exist
Source
Quentin Meillassoux (After Finitude; the necessity of contingency [2006], 3)
Book Reference
Meillassoux: 'After Finitude: the necessity of contingency', ed/tr. Brassier,R [Bloomsbury 2008], p.76
A Reaction
The great charm of metaphysics is the array of serious answers to the question of why there is something rather than nothing. You'll need to read Meillassoux's book to understand this one.