TO see into our nation's third century with any degree of certainty so obviously exceeds a man's reach that the first reaction is to reexamine such a possibility. A former secretary of state when asked how he handled congressional hearings replied that when asked a question he could not answer, he answered another one. It may be possible to see a few years ahead, but who can claim even a quarter-century of forward vision? That remarkable group of men who made up the first Policy Planning Staff in the Department of State under Secretary of State George C. Marshall discovered that looking ahead beyond the span of three to five years was a practical impossibility. They also learned that if the planner was to influence foreign policy he needed to become an operator, and this restricted attention to more immediate problems and narrowed the span of relevant planning to a year or two, if that.

Yet scholars and informed observers continue to hear a call for responsible forecasting, and the more brash among us appear unable to resist answering it. At one level it is possible