An asset in his role as public intellectual, if possibly a regrettable one for the reception of his work as whole, was Hirschman's persistent, aphoristic habit of elevating deceptively simple, counterintuitive observations as grand principles of the human condition.The most famous of these, the "Principle of the Hiding Hand" (a knowing nod to Adam Smith's invisible hand), states that in large human undertakings—dam construction, say—we tend to underestimate the difficulties involved. This makes us likelier to get going than we otherwise would have been, had we known all the problems in advance. We also underestimate our creativity in solving problems as they arise, which makes us likelier to succeed than a sober assessment might have determined at the outset.
http://bostonreview.net/class-inequality-politics-philosophy-religion/simon-torracinta-we-dont-know-lets-try-it