Common sense has the very curious property of being more correct retrospectively than prospectively, it seems to me that one of the principal criteria to be applied to successful projects is that its results are almost always obvious retrospectively; unfortunately, they seldom are successful prospectively. Common sense provides a kind of ultimate validation after the work; after the project has completed its work; it seldom anticipates what the work is going to discover.
— Russel Lincoln Ackoff, The Art of Problem Solving, 1978
