Moreover, core beliefs and style constrain policy makers profoundly. So don't ask them to do something outside their range of psychological possibility by, for example, proposing cold-eyed realpolitik to a band of idealists or vice versa. There are no platonic ideal-type policies, valid no matter who is in charge. What may make sense for one administration may make no sense for another, not because of the external environment, but because of who has to execute the policy and live with its consequences.