Wednesday, April 25, 2012

By Root or by Branch


For complex problems, the first of these two approaches is of course impossible. Although such an approach can be described, it cannot be practiced except for relatively simple problems and even then only in a somewhat modified form. It assumes intellectual capacities and sources of information that men simply do not possess, and it is even more absurd as an approach to policy when the time and money that can be allocated to a policy problem is limited, as is always the case. Of particular importance to public administrators is the fact that public agencies are in effect instructed not to practice the first method. That is to say, their prescribed functions and constraints - the politically or legally possible - restrict their attention to relatively few values and relatively few alternative policies among the countless alternatives that might be imagined. It is the second method that is practiced.
Curiously, however, the literatures of decision-making, policy formulation, planning, and public administration formalize the first approach rather than the second, leaving public administrators who handle complex decisions in the position of practicing what few preach. For emphasis I run some risk of over-statement. True enough, the literature is well aware of limits on man's capacities and of the inevitability that policies will be approached in some such style as the second. But attempts to formalize rational policy formulation - to lay out explicitly the necessary steps in the process - usually describe the first approach and not the second.'
The common tendency to describe policy formulation even for complex problems as though it followed the first approach has been strengthened by the attention given to, and successes enjoyed by, operations research, statistical decision theory, and systems analysis. The hallmarks of these procedures, typical of the first approach, are clarity of objective, explicitness of evaluation, a high degree of comprehensiveness of overview, and, wherever possible, quantification of values for mathematical analysis. But these advanced procedures remain largely the appropriate techniques of relatively small-scale problem-solving where the total number of variables to be considered is small and value problems restricted. Charles Hitch, head of the Economics Division of RAND Corporation, one of the leading centers for application of these techniques, has written:
I would make the empirical generalization from my experience at RAND and elsewhere that operations research is the art of sub-optimizing, that is, of solving some lower-level problems, and that difficulties increase and our special competence diminishes by an order of magnitude with every level of decision-making we attempt to ascend. The sort of simple explicit model which operations researchers are so proficient in using can certainly reflect most of the significant factors influencing traffic control on the George Washington Bridge, but the proportion of the relevant reality which we can represent by any such model or models in studying, say, a major foreign-policy decision, appears to be almost trivial.2
Accordingly, I propose in this paper to clarify and formalize the second method, much neglected in the literature. This might be described as the method of successive limited comparisons. I will contrast it with the first approach, which might be called the rational-comprehensive method.' More impressionistically and briefly - and therefore generally used in this article - they could be characterized as the branch method and root method, the former continually building out from the current situation, step-by-step and by small degrees; the latter starting from fundamentals anew each time, building on the past only as experience is embodied in a theory, and always prepared to start completely from the ground up.
Let us put the characteristics of the two methods side by side in simplest terms.

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