All events but the truly unique require a generic solution. They require a rule, a policy, or a principle. Once the right principle has been developed, all manifestations of the same generic situation can be handled pragmatically—that is, by adaptation of the rule to the concrete circumstances of the case. Truly unique events, however, must be treated individually. The executive cannot develop rules for the exceptional.
The effective decision maker spends time determining which of the four different situations is happening. The wrong decision will be made if the situation is classified incorrectly.
By far the most common mistake of the decision maker is to treat a generic situation as if it were a series of unique events—that is, to be pragmatic when lacking the generic understanding and principle. The inevitable result is frustration and futility.
Equally common is the mistake of treating a new event as if it were just another example of the old problem to which, therefore, the old rules should be applied.Peter Drucker, The Effective Decision, HBR1967