...our knowledge of possible worlds is, in general, no more than an inference from our knowledge of God....But because our understanding is not the unrestricted act, we are not in a position to go into details. Briefly, we are committed to the sobriety of Aquinas in the twenty-fifth question of the first part of his Summa theologiae, and we are led to reject as methodologically unsound the Scotist view that a question becomes scientific when it is raised with respect to all possible worlds. The fact is that a question then usually becomes indeterminable....
Bernard Lonergan, Insight, p. 702
I'm not sure how Scotist the methodology is, but it is certainly something requiring caution and sobriety. Possible worlds analysis makes, I think, a great many questions indeterminable.
