No president enters office knowing everything he needs to know. His experience is limited to some greater or lesser extent; his knowledge of the people from whom he will choose appointees is incomplete; his mastery of the substance of public policy, after years on the campaign trail, is likely to be out of date. And like all of us, he does not know what the future will bring.

So presidents must rely on something else, something intangible and unquantifiable, in determining what is within the realm of possibility and what is a bridge too far: intuition.

No president enters office knowing everything he needs to know. His experience is limited to some greater or lesser extent; his knowledge of the people from whom he will choose appointees is incomplete; his mastery of the substance of public policy, after years on the campaign trail, is likely to be out of date. And like all of us, he does not know what the future will bring.

So presidents must rely on something else, something intangible and unquantifiable, in determining what is within the realm of possibility and what is a bridge too far: intuition.