Randy likes to sit on his porch overlooking his frozen lake as snow approaches from the mountains to the west. A flock of geese land on the snow-covered ice. The ice breaks and rows of geese, quite unaware of the hidden risks, cascade into the chilly water. We sense a teaching moment. Not surprisingly, but perhaps incongruously, we recall the words of the infamous and humorous Donald Rumsfeld, former U.S. Secretary of Defense, who once spoke volubly on the absence of evidence linking the supply of weapons of mass destruction to the star-crossed war in Iraq

“[T]here are known knowns; there are things we know that we know. There are known unknowns; that is to say there are things that, we now know we don’t know. But there are also unknown unknowns — there are things we do not know we don’t know.”

Known knowns are generally amenable to quantification. Then there are unknown risks. For cognitive reasons we are vaguely aware