When David Hume (Dialogues concerning Natural Religion) protests that the universe is a " singular effect " and that we have no right to affirm a cause for it, unless we have experience of the origin of many universes, and can generalize the conclusion, They all have causes - he may be unassailable upon empiricist grounds.
The universe exists - or, as otherwise stated, the universe is " contingent " - therefore, even without detailed knowledge of different universes, we can affirm that it must be caused, and in its " Great First Cause " we recognize God.'
Similarly, James is willing to believe in many universes nebeneinander or durcheinander but not (ineinander.
But why must universes be so bad?
Thus we are led to regard the two systems as completely intermingled, a fact which adds considerably to the difficulty of explaining the phenomena otherwise than as produced by two great systems - universes they have been called - which have come together, perhaps, by their mutual attraction, and are passing through one another.
How would you define universes? Add your definition here.