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Policy Sciences 4 (1973), 155-169 © Elsevier Scientific Publishing Company, Amsterdam--Printed in Scotland

Dilemmas in a General Theory of Planning* H O R S T W . J . R I T T E L

Professor of the Science of Design, University of California, Berkeley

M E L V I N M. W E B B E R

Professor of City Planning, University of California, Berkeley

A B S T R A C T

The search for scientific bases for confronting problems of social policy is bound to fail, because of the nature of these problems. They are "wicked" problems, whereas science has developed to deal with "tame" problems. Policy problems cannot be definitively described. Moreover, in a pluralistic society there is nothing like the undisputable public good; there is no objective definition of equity; policies that respond to social problems cannot be meaningfully correct or false; and it makes no sense to talk about "optinaal solutions" to social probIems unless severe qualifications are imposed first. Even worse, there are no "solutions" in the sense of definitive and objective answers.

G e o r g e B e r n a r d S h a w d i a g n o s e d the case several years a g o ; in m o r e r e c e n t times p o p u l a r p r o t e s t m a y h a v e a l r e a d y b e c o m e a social m o v e m e n t . S h a w a v e r r e d t h a t " e v e r y p r o f e s s i o n is a c o n s p i r a c y against the l a i t y . " T h e c o n t e m p o r a r y publics are r e s p o n d i n g as t h o u g h t h e y h a v e m a d e the same discovery.

F e w o f the m o d e r n p r o f e s s i o n a l s seem t o be i m m u n e f r o m the p o p u l a r a t t a c k - - w h e t h e r t h e y be social w o r k e r s , e d u c a t o r s , h o u s e r s , p u b l i c h e a l t h officials, p o l i c e m e n , city p l a n n e r s , h i g h w a y engineers o r physicians. O u r restive clients h a v e b e e n telling us t h a t t h e y d o n ' t like the e d u c a t i o n a l p r o g r a m s t h a t s c h o o l m e n h a v e b e e n offering, the r e d e v e l o p m e n t p r o j e c t s u r b a n renewal agencies h a v e b e e n p r o p o s i n g , the law- e n f o r c e m e n t styles o f the police, the a d m i n i s t r a t i v e b e h a v i o r o f the welfare agencies, t h e l o c a t i o n s o f the h i g h w a y s , a n d so on. I n t h e c o u r t s , t h e streets, a n d t h e political c a m p a i g n s , w e ' v e b e e n h e a r i n g e v e r - l o u d e r p u b l i c p r o t e s t s a g a i n s t the p r o f e s s i o n s ' d i a g n o s e s o f the clients' p r o b l e m s , a g a i n s t p r o f e s s i o n a l l y d e s i g n e d g o v e r n m e n t a l p r o g r a m s , a g a i n s t p r o f e s s i o n a l l y certified s t a n d a r d s f o r the p u b l i c services.

I t d o e s seem o d d t h a t this a t t a c k s h o u l d be c o m i n g j u s t w h e n p r o f e s s i o n a l s in

* This is a modification of a paper presented to the Panel on Policy Sciences, American Association for the Advancement of Science, Boston, December 1969.

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the social services are beginning to acquire professional competencies. It might seem that our publics are being perverse, having c o n d o n e d professionalism when it was really only dressed-up amateurism and condemning professionalism when we finally seem to be getting good at o u r jobs. Perverse tho u g h the laity m a y be, surely the professionals themselves have been behind this attack as well.

Some o f the generators o f the confrontation have been intellectual in origin. Th e anti-professional m o v e m e n t stems in part f r o m a reconceptualization o f the pro- fessional's task. Others are more in the character o f historical imperatives, i.e. con- ditions have been thrown up by the course o f societal events t h a t call fo r different modes o f intervention.

The professional's j o b was once seen as solving an assortment o f problems that appeared to be definable, understandable and consensual. H e was hired to eliminate those conditions that predominant opinion judged undesirable. His record has been quite spectacular, o f course; the c o n t e m p o r a r y city a n d c o n t e m p o r a r y urban society stand as clean evidences o f professional prowess. The streets have been paved, and roads now connect all places; houses shelter virtually everyone; the dread diseases are virtually gone; clean water is piped into nearly every building; sanitary sewers carry wastes f r o m them; schools and hospitals serve virtually every district; a n d so on. The accomplishments o f the past century in these respects have been truly pheno- menal, however short o f some persons' aspirations they might have been.

But now that these relatively easy problems have been dealt with, we have been turning o u r attention to others that are much m o r e stubborn. Th e tests fo r efficiency, that were once so useful as measures o f accomplishment, are being challenged by a renewed preoccupation with consequences for equity. The seeming consensus, that might once have allowed distributional problems to be dealt with, is being eroded by the growing awareness o f the nation's pluralism a n d o f the differentiation o f values that accompanies differentiation o f publics. Th e professionalized cognitive and occupational styles that were refined in the first h a l f o f this century, based in Newtonian mechanistic physics, are not readily adapt e d to c o n t e m p o r a r y conceptions o f interacting open systems and to c o n t e m p o r a r y concerns with equity. A growing sensitivity to the waves o f repercussions that ripple t h r o u g h such systemic networks and to the value consequences o f those repercussions has generated the recent re- examination o f received values a n d the recent search fo r national goals. There seems to be a growing realization that a weak strut in the professional's support system lies at the juncture where goal-formulation, problem-definition a n d equity issues meet. We should like to address these matters in turn.

I. G o a l F o r m u l a t i o n

The search for explicit goals was initiated in force with the opening o f the 1960s. In a 1960 R A N D publication, Charles J. Hitch urged that " W e must learn to l o o k at o u r o b j e c t i v e s as critically and as professionally as we l o o k at o u r models and o u r other inputs." 1 The subsequent work in systems analysis reaffirmed that injunction.

1 Charles J. Hitch, "On the Choice of Objectives in Systems Studies" (Santa Monica, California: The RAND Corporation, 1960; P-1955), p. 19.

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M e n in a wide a r r a y o f fields were p r o m p t e d to redefine the systems they dealt with in the syntax o f verbs r a t h e r t h a n n o u n s - - t o a s k " W h a t d o the systems do ?" r a t h e r t h a n " W h a t are they m a d e o f ? " - - a n d then to a s k the m o s t difficult question o f all: " W h a t shouM these systems d o ?" Also 1960 was i n a u g u r a t e d with the p u b l i c a t i o n o f Goals for Americans, the r e p o r t o f President E i s e n h o w e r ' s C o m m i s s i o n o n N a t i o n a l Goals.2 There followed then a wave o f similar efforts. The C o m m i t t e e for E c o n o m i c D e v e l o p m e n t commissioned a fo!low-u p re-examination. So did the Brookings Institution, the A m e r i c a n A c a d e m y o f A r t s a n d Sciences, a n d then President N i x o n t h r o u g h his N a t i o n a l G o a l s Research Staff. But2these m a y be only the m o s t a p p a r e n t a t t e m p t s to clarify the n a t i o n ' s directions.3

Perhaps m o r e s y m p t o m a t i c in the U.S. were the efforts to install PPBS, which requires explication o f desired outcomes; a n d then the m o r e recent a t t e m p t s to build systems o f social indicators, which are in effect surrogates for statements o f desired conditions. As we all now know, it has t u r n e d out t o be terribly difficult, i f n o t i m - possible, to m a k e either o f these systems operational. A l t h o u g h there are some small success stories recounted in a few civilian agencies, successes are still rare. Goal-finding is turning o u t t o be a n extraordinarily obstinate task. Because goal-finding is one o f the central functions o f planning, we shall shortly want to a s k why t h a t m u s t be so.

A t the same time t h a t these formalized a t t e m p t s were being m a d e to discover o u r latent aims, the nation was buffeted by the revolt o f the blacks, then b y the revolt o f the students, then b y the widespread revolt against the war, m o r e recently with a new c o n s u m e r i s m and conservationism. All these m o v e m e n t s were striking o u t a t the underlying systemic processes o f c o n t e m p o r a r y A m e r i c a n society. I n a style r a t h e r different f r o m those o f the systems analysts a n d the Presidential commissioners, participants in these revolts were seeking t o restructure the value a n d goal systems t h a t affect the distribution o f social p r o d u c t a n d shape the directions o f national policy.

Systems analysis, goals commissions, PPBS, social indicators, the several revolts, the p o v e r t y p r o g r a m , model cities, the current concerns with e n v i r o n m e n t a l quality a n d with the qualities o f u r b a n life, the search f o r new religions a m o n g c o n t e m p o r a r y youth, and the increasing attractiveness o f the planning i d e a - - a l l seem to be driven b y a c o m m o n quest. Each in its peculiar way is asking f o r a clarification o f purposes, f o r a redefinition o f problems, for a re-ordering o f priorities to m a t c h stated purposes, f o r the design o f new kinds o f goal-directed actions, for a reorientation o f the p r o - fessions to the o u t p u t s o f professional activities r a t h e r t h a n to the inputs into them, a n d then f o r a redistribution o f the o u t p u t s o f g o v e r n m e n t a l p r o g r a m s a m o n g the c o m p e t i n g publics.

A deep-running current o f o p t i m i s m in A m e r i c a n t h o u g h t seems to have been propelling these diverse searches f o r direction-finding instruments. But a t the same time, the A m e r i c a n s ' traditional faith in a g u a r a n t e e d Progress is being e r o d e d b y the same waves t h a t are wearing d o w n old beliefs in the social o r d e r ' s inherent goodness a n d in history's intrinsic benevolence. Candide is dead. H i s place is being

2 The report was published by Spectrum Books, Prentice-Hall, 1960. 3 At the same time to be sure, counter voices--uncomfortable to many--were claiming that the

"nation's direction" presents no meaningful reference system at all, owing to the worldwide character of the problems and the overspill of crises across national boundaries.

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occupied by a new conception o f future history that, rejecting historicism, is searching for ways o f exploiting the intellectual and inventive capabilities o f men.

This belief comes in two quite c o n t r a d i c t o r y forms. On the one hand, there is the belief in the " m a k e a b i l i t y , " or unrestricted malleability, o f future history by means o f the planning i n t e l l e c t - - b y reasoning, rational discourse, a n d civilized negotiation. At the same time, there are vocal p r o p o n e n t s o f the "feeling a p p r o a c h , " o f com- passionate engagement and dramatic action, even o f a revival o f mysticism, aiming at overcoming The System which is seen as the evil source o f misery and suffering.

The Enlightenment m a y be coming to full maturity in the late 20th century, or it may be o n its deathbed. Many Americans seem to believe b o t h that we can perfect future h i s t o r y - - t h a t we can deliberately shape future outcomes to accord with o u r w i s h e s - - a n d that there will be no future history. Some have arrived at deep pessimism and some at resignation. T o them, planning for large social systems has p r o v e d to be impossible without loss o f liberty and equity. Hence, for them the ultimate goal o f planning should be anarchy, because it should aim at the elimination o f govern- ment over others. Still a n o t h e r group has arrived at the conclusion that liberty and equity are luxuries which cannot be afforded by a m o d e r n society, a n d t h a t they should be substituted by "cybernetically feasible" values.

Professionalism has been understood to be one o f the major instruments for perfectability, an agent sustaining the traditional American optimism. Based in m o d e r n science, each o f the professions has been conceived as the medium t h ro u g h which the knowledge o f science is applied. In effect, each profession has been seen as a subset o f engineering. Planning and the emerging policy sciences are a mo n g the more optimistic o f those professions. Their representatives refuse t o believe that planning for betterment is impossible, however grave their misgivings a b o u t the appropriateness o f past and present modes o f planning. T h e y have not a b a n d o n e d the hope t h a t the instruments o f perfectability can be perfected. It is that view that we want to examine, in an effort to ask whether the social professions are equipped to do what they are expected to do.

H. Problem Definition

During the industrial age, the idea o f planning, in c o m m o n with the idea o f pro- fessionalism, was dominated by the pervasive idea o f efficiency. D ra w n fro m 18th century physics, classical economics and the principle o f least-means, efficiency was seen as a condition in which a specified task could be p e rfo rme d with low inputs o f resources. T h a t has been a powerful idea. It has long been the guiding concept o f civil engineering, the scientific m a n a g e m e n t movement, mu c h o f c o n t e m p o r a r y operations research; and it still pervades m o d e r n government a n d industry. When attached to the idea o f planning, it became dominating there too. Planning was then seen as a process o f designing problem-solutions that might be installed and operated cheaply. Because it was fairly easy to get consensus on the nature o f problems during the early industrial period, the task c o u l d be assigned to the technically skilled, w h o in turn could be trusted to accomplish the simplified end-in-view. Or, in the mo re work-a-day setting, we could rely u p o n the efficiency expert to diagnose a p ro b l e m

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and then solve it, while simultaneously reducing the resource inputs into whatever it was we were doing.

We have come to think a b o u t the planning task in very different ways in recent years. We have been learning to ask whether what we are doing is the right thing to do. T h a t is to say, we have been learning to ask questions a b o u t the outputs o f actions and to pose problem statements in valuative frameworks. We have been learning to see social processes as the links tying open systems into large a n d interconnected networks o f systems, such that outputs f r o m one become inputs to others. In t h a t structural framework it has become less a p p a r e n t where problem centers lie, a n d less apparent where and how we should intervene even i f we d o h a p p e n to k n o w w h a t aims we seek. We are now sensitized to the waves o f repercussions generated b y a problem-solving action directed to any one node in the network, and we are no longer surprised to find it inducing problems o f greater severity at some o t h e r node. A n d so we have been forced to expand the boundaries o f the systems we deal with, trying to internalize those externalities.

This was the professional style o f the systems analysts, who were c o m m o n l y seen as forebearers o f the universal problem-solvers. With arrogant confidence, the early systems analysts p r o n o u n c e d themselves ready to take on anyone's perceived problem, diagnostically to discover its hidden character, and then, having exposed its true nature, skillfully to excise its r o o t causes. T w o decades o f experience have w o rn t h e self-assurances thin. These analysts are coming to realize h o w valid their model really is, f or they themselves have been caught by the very same diagnostic difficulties t h a t troubled their clients.

By now we are all beginning to realize that one o f the most intractable problems is that o f defining problems (of knowing what distinguishes an observed condition from a desired condition) and o f locating problems (finding where in the complex causal networks the trouble really lies). In turn, and equally intractable, is the p r o b l e m o f identifying the actions that might effectively n a r r o w the gap between what-is and what-ought-to-be. As we seek to improve the effectiveness o f actions in pursuit o f valued outcomes, as system boundaries get stretched, a n d as we become m o r e sophisticated a b o u t the complex workings o f open societal systems, it becomes ever more difficult to make the planning idea operational.

M a n y now have an image o f how an idealized planning system would function. It is being seen as an on-going, cybernetic process o f governance, incorporating systematic procedures for continuously searching out goals; identifying problems; forecasting uncontrollable contextual changes; inventing alternative strategies, tactics, a n d time- sequenced actions; stimulating alternative and plausible action sets a n d their con- sequences; evaluating alternatively forecasted outcomes; statistically m o n i t o r i n g those conditions o f the publics a n d o f systems that are j u d g e d t o be germane; feeding back information to the simulation a n d decision channels so t h a t errors c a n be c o r r e c t e d - - a l l in a simultaneously functioning governing process. T h a t set o f steps is familiar to all o f us, for it comprises what is by n o w the modern-classical model o f planning. A n d yet we all k n o w that such a planning system is unattainable, even as we seek more closely to approximate it. It is even questionable whether such a plan- ning system is desirable.

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IH. Planning Problems are Wicked Problems

A great many barriers keep us f r o m perfecting such a planning/governing system: theory is inadequate for decent forecasting; o u r intelligence is insufficient to o u r tasks; plurality o f objectives held by pluralities o f politics makes it impossible to pursue unitary aims; and so on. The difficulties attached to rationality are tenacious, and we have so far been unable to get untangled fro m their web. This is partly because the classical paradigm o f science and eng i n e e ri n g --t h e paradigm that has underlain m o d e r n professionalism--is not applicable to the problems o f open societal systems. One reason the publics have been attacking the social professions, we believe, is that the cognitive and occupational styles o f the professions--mimicking the cognitive style o f science and the occupational style o f engineering---have just not worked on a wide array o f social problems. T h e lay customers are complaining because planners and other professionals have not succeeded in solving the problems they claimed they could solve. We shall want to suggest t h a t the social professions were misled somewhere along the line into assmning they could be applied scientists-- that they could solve problems in the ways scientists can solve their sorts o f problems. T h e e r r o r has been a serious one.

The kinds o f problems that planners deal with--societal p r o b l e m s - - a r e inherently different f r o m the problems that scientists and perhaps some classes o f engineers deal with. Planning problems are inherently wicked.

As distinguished from problems in the natural sciences, which are definable and separable and may have solutions t h a t are findable, the p r o N e m s o f governmental p l a n n i n g - - a n d especially those o f social or policy p l a n n i n g - - a r e ill-defined; and they rely upon elusive political j u d g m e n t for resolution. (N o t " s o l u t i o n . " Social problems are never solved. A t best they are only r e - s o l v e d - - o v e r and over again.) Permit us to draw a cartoon that will help clarify the distinction we intend.

The problems that scientists and engineers have usually focused u p o n are mostly " t a m e " or " b e n i g n " ones. As an example, consider a problem o f mathematics, such as solving an equation; or the task o f an organic chemist in analyzing the structure o f some u n k n o w n c o m p o u n d ; or that of the chessplayer attempting to accomplish checkmate in five moves. F o r each the mission is clear. It is clear, in turn, whether o r not the problems have been solved.

Wicked problems, in contrast, have neither o f these clarifying traits; a n d they include nearly all public policy issues--whether the question concerns the location o f a freeway, the adjustment o f a tax rate, the modification o f school curricula, or the c o n f r o n t a t i o n o f crime.

There are at least ten distinguishing properties o f planning-type problems, i.e. wicked ones, that planners h a d better be alert to and which we shall comment u p o n in turn. As y o u will see, we are calling them " w i c k e d " not because these properties are themselves ethically deplorable. We use the ter m " w i c k e d " in a meaning akin to that o f " m a l i g n a n t " (in contrast to " b e n i g n " ) or " v i c i o u s " (like a circle) or " t r i c k y " (like a leprechaun) or "aggressive" (like a lion, in contrast to the docility o f a lamb). We do not mean to personify these properties o f social systems by implying malicious

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intent. But then, y o u may agree that it becomes morally objectionable fo r the planner to treat a wicked problem as though it were a tame one, o r to tame a wicked problem prematurely, or to refuse to recognize the inherent wickedness o f social problems.

1. T h e r e is no definitive f o r m u l a t i o n o f a w i c k e d p r o b l e m

F o r any given tame problem, an exhaustive formula t i o n can be stated containing all the information the problem-solver needs for understanding a n d solving the p r o b l e m - - p r o v i d e d he knows his " a r t , " o f course.

This is not possible with wicked-problems. The i n fo rma t i o n needed to understand the problem depends upon one's idea for solving it. T h a t is to say: in o rd e r to describe a wicked-problem in sufficient detail, one has to develop an exhaustive inventory o f all conceivable solutions ahead o f time. The reason is that every question asking fo r additional information depends upon the understanding o f the p r o b l e m - - a n d its r e s o l u t i o n - - a t that time. Problem understanding a n d p r o b l e m resolution are con- comitant to each other. Therefore, in order to anticipate all questions (in o rd e r t o anticipate all information required for resolution ahead o f time), knowledge o f all conceivable solutions is required.

Consider, for example, what would be necessary in identifying the nature o f the p o v e r t y problem. Does p o v e r t y mean low i n c o m e ? Yes, in part. But what are the determinants o f low income ? Is it deficiency o f the national a n d regional economies, or is it deficiencies o f cognitive and occupational skills within the labor force ? I f the latter, the problem statement and the problem " s o l u t i o n " must encompass the educa- tional processes. But, then, where within the educational system does the real p ro b l e m lie ? W h a t then might it mean to " i m p r o v e the educational s y s t e m " ? O r does the poverty problem reside in deficient physical and mental health ? I f so, we must a d d those etiologies to o u r information package, and search inside the health services f o r a plausible cause. Does it include cultural de p ri v a t i o n ? spatial dislocation? problems o f ego identity ? deficient political and social skills ? - - a n d so on. I f we can formulate the problem by tracing it to some sorts o f s o u r c e s - - s u c h t h a t we can say, " A h a ! That's the locus o f the difficulty," i.e. those are the r o o t causes o f the differences between the " i s " and the " o u g h t to b e " c o n d i t i o n s - - t h e n we have thereby also f o r m u l a t e d a solution. T o find the problem is thus the same thing as finding the solution; the problem can't be defined until the solution has been found.

The formulation o f a wicked problem is the p r o b l e m ! The process o f formulating the p r o b l e m and o f conceiving a solution (or re-solution) are identical, since every specification o f the problem is a specification o f the direction in which a t re a t me n t is considered. Thus, if we recognize deficient mental health services as p a rt o f the problem, then--trivially e n o u g h - - " i m p r o v e m e n t o f mental health services" is a specification o f solution. If, as the next step, we declare the lack o f c o m m u n i t y centers one deficiency o f the mental health services system, t h e n " p r o c u r e m e n t o f c o m m u n i t y centers" is the next specification o f solution. I f it is inadequate treatment within community centers, then improved t h e r a p y training o f staff m a y be the locus o f solution, and so on.

This p r o p e r t y sheds some tight on the usefulness o f the famed " s y s t e m s - a p p r o a c h "

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f o r treating wicked problems. The classical systems-approach o f the military a n d the space programs is based on the assumption t h a t a planning project can be organized into distinct phases. Every t e x t b o o k o f systems engineering starts with an enumeration o f these phases: " u n d e r s t a n d the problems or the mission," " g a t h e r i n f o r m a t i o n , " "analyze i n f o r m a t i o n , " "synthesize information an d wait for the creative leap," " w o r k o u t solution," or the like. F o r wicked problems, however, this type o f scheme does not work. One cannot understand the problem without knowing a b o u t its context; one cannot meaningfully search for information w i t h o u t the orientation o f a solution concept; one cannot first understand, then solve. T h e systems-approach " o f the first generation" is inadequate for dealing with wicked-problems. Approaches o f the "second generation" should be based on a :model o f planning as an argumen- tative process in the course o f which an image o f the p ro b l e m a n d o f the solution emerges gradually among the participants, as a p r o d u c t o f incessant judgment, subjected to critical argument. The methods o f Operations Research play a prominent role in the systems-approach o f the first generation; they become operational, how- ever, only after the most i m p o r t a n t decisions have already been made, i.e. after the problem has already been tamed.

Take an optimization model. Here the inputs needed include the definition o f the solution space, the system o f constraints, and the performance measure as a function o f the planning and contextual variables. But setting u p and constraining the solution space and constructing the measure o f performance is the wicked p a r t o f the problem. Very likely it is more essential than the remaining steps o f searching for a solution which is optimal relative to the measure of performance and the constraint system.

2. W i c k e d problems have no stopping rule

In solving a chess problem or a mathematical equation, the problem-solver knows when he has done his job. There are criteria that tell when the o r a solution has been found.

N o t so with planning problems. Because (according to Proposition 1) the process o f solving the problem is identical with the process o f understanding its nature, because there are no criteria for sufficient understanding and because there are n o ends to the causal chains that link interacting open systems, the would-be planner can always try to do better. Some additional investment o f effort might increase the chances o f finding a better solution.

The planner terminates w o r k on a wicked problem, n o t fo r reasons inherent in the " l o g i c " o f the problem. He stops for considerations that are external to the problem: he runs out o f time, or money, or patience. He finally says, " T h a t ' s good e n o u g h , " o r " T h i s is the best I can do within the limitations o f the project," or " I like this solution," etc.

3. Solutions to wicked problems are n o t true-or-false, but good-or-bad

There are conventionalized criteria for objectively deciding whether the offered solution to an equation or whether the proposed structural f o r m u l a o f a chemical c o m p o u n d is correct or false. They can be independently checked b y other qualified

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persons who are familiar with the established criteria; a n d the answer will b e n o r m a l l y u n a m b i g u o u s .

F o r wicked planning problems, there are no true or false answers. N o r m a l l y , m a n y parties are equally equipped, interested, a n d / o r entitled to judge the solutions, a l t h o u g h none has the p o w e r to set f o r m a l decision rules to determine correctness. Their j u d g m e n t s are likely to differ widely to accord with their g r o u p or personal interests, their special value-sets, a n d their ideological predilections. T h e i r assess- ments o f p r o p o s e d solutions are expressed as " g o o d " o r " b a d " or, m o r e likely, as " b e t t e r o r w o r s e " o r " s a t i s f y i n g " or " g o o d e n o u g h . "

4. There is no immediate and no ultimate test o f a solution to a wicked problem

F o r t a m e - p r o b l e m s one can determine o n the spot h o w g o o d a s o l u t i o n - a t t e m p t has been. M o r e accurately, the test o f a solution is entirely u n d e r the c o n t r o l o f the few p e o p l e w h o are involved a n d interested in the p r o b l e m .

With wicked p r o b l e m s , on the other hand, a n y solution, after being i m p l e m e n t e d , will generate waves o f consequences over a n e x t e n d e d - - v i r t u a l l y a n u n b o u n d e d - - period o f time. M o r e o v e r , the next d a y ' s consequences o f the solution m a y yield utterly undesirable repercussions which outweigh the intended a d v a n t a g e s or the advantages accomplished hitherto. In such cases, one would have been b e t t e r off i f the p l a n h a d never been carried out.

The full consequences c a n n o t be appraised until the waves o f repercussions h a v e completely r u n out, a n d we have no w a y o f tracing all the waves t h r o u g h all the affected lives a h e a d o f time or within a limited time span.

5. Every solution to a wicked problem is a "one-shot operation"; because there is no opportunity to learn by trial-and-error, every attempt counts significantly

In the sciences and in fields like m a t h e m a t i c s , chess, puzzle-solving o r m e c h a n i c a l engineering design, the p r o b l e m - s o l v e r c a n t r y various runs w i t h o u t penalty. W h a t - ever his o u t c o m e on these individual experimental runs, it d o e s n ' t m a t t e r m u c h t o the subject-system or to the course o f societal affairs. A lost chess game is s e l d o m consequential f o r other chess games or f o r non-chess-players.

With wicked planning problems, however, every i m p l e m e n t e d solution is con- sequential. I t leaves " t r a c e s " t h a t c a n n o t be undone. One c a n n o t build a freeway t o see h o w it works, a n d then easily correct it after unsatisfactory p e r f o r m a n c e . L a r g e public-works are effectively irreversible, a n d the consequences they generate have long half-lives. M a n y p e o p l e ' s lives will have been irreversibly influenced, a n d large a m o u n t s o f m o n e y will have been s p e n t - - a n o t h e r irreversible act. T h e s a m e h a p p e n s with m o s t other large-scale public w o r k s a n d w i t h virtually all puNic-service p r o - grams. T h e effects o f a n experimental curriculum will follow the pupils into their adult lives.

W h e n e v e r actions are effectively irreversible a n d whenever the half-lives o f the consequences are long, every trial counts. A n d every a t t e m p t to reverse a decision or to correct f o r the undesired consequences poses a n o t h e r set o f wicked p r o b l e m s , which are in turn subject to the same dilemmas.

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6. Wicked problems do not have an enumerable (or an exhaustively describable) set of potential solutions, nor is there a well-described set o f permissible operations that may be incorporated into the plan

There are no criteria which enable one to p r o v e t h a t all solutions to a wicked p r o b l e m h a v e been identified a n d considered.

I t m a y h a p p e n t h a t no solution is found, owing t o logical inconsistencies in the " p i c t u r e " o f the p r o b l e m . ( F o r example, the p r o b l e m - s o l v e r m a y arrive at a p r o b l e m description requiring t h a t b o t h A and not-A should h a p p e n at the same time.) O r it might result f r o m his failing t o develop a n idea f o r solution (which does not m e a n t h a t s o m e o n e else might be m o r e successful). But normally, in the pursuit o f a wicked planning p r o b l e m , a host o f potential solutions arises; a n d a n o t h e r host is never t h o u g h t up. I t is then a m a t t e r o f judgment whether one should try to enlarge the available set or not. A n d it is, o f course, a m a t t e r o f j u d g m e n t which o f these solutions should be pursued a n d implemented.

Chess has a finite set o f rules, accounting f o r all situations t h a t can occur. I n mathematics, the tool chest o f operations is also explicit; so, too, although less rigorously, in chemistry.

But not so in the world o f social policy. Which strategies-or-moves are permissible in dealing with crime in the streets, f o r example, have been e n u m e r a t e d nowhere. " A n y t h i n g goes," or at least, a n y :new idea f o r a planning m e a s u r e m a y b e c o m e a serious candidate for a re-solution: W h a t should we do to reduce street c r i m e ? Should we disarm the police, as they do in England, since even criminals are less likely to s h o o t u n a r m e d m e n ? O r repeal the laws t h a t define crime, such as those t h a t m a k e m a r i j u a n a use a criminal act or those t h a t m a k e car theft a criminal act ? T h a t would reduce crime b y changing definitions. T r y m o r a l r e a r m a m e n t and substitute ethical self-control for police a n d court control ? S h o o t all criminals and thus reduce the n u m b e r s w h o c o m m i t c r i m e ? Give a w a y free loot to would-be-thieves, a n d so reduce the incentive to crime ? A n d so on.

I n such fields o f ill-defined p r o b l e m s a n d hence ill-definable solutions, the set o f feasible plans o f action relies on realistic j u d g m e n t , the capability to appraise " e x o t i c " ideas a n d o n the a m o u n t o f trust a n d credibility between p l a n n e r a n d clientele t h a t wilt lead t o the conclusion, " O K let's try t h a t . "

7. Every wicked problem is essentially unique

O f course, f o r a n y two p r o b l e m s at least one distinguishing p r o p e r t y can be f o u n d (just as a n y n u m b e r o f properties can be f o u n d which they share in c o m m o n ) , a n d each o f t h e m is therefore unique in a trivial sense. But b y "'essentially u n i q u e " we m e a n that, despite long lists o f similarities between a current p r o b l e m and a previous one, there always might be a n additional distinguishing p r o p e r t y t h a t is o f overriding importance. P a r t o f the a r t o f dealing with wicked p r o b l e m s is the a r t o f n o t k n o w i n g t o o early which type o f solution to apply.

There are n o classes o f wicked p r o b l e m s in the sense t h a t principles o f solution can be developed to fit all m e m b e r s o f a class. I n m a t h e m a t i c s there are rules for classifying families o f p r o b l e m s - - s a y , o f solving a class o f e q u a t i o n s - - w h e n e v e r a

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certain, quite-well-specified set o f characteristics matches the problem. There are explicit characteristics o f tame problems that define similarities a m o n g them, in such fashion that the same set o f techniques is likely to be effective on all o f them.

Despite seeming similarities among wicked problems, one can never be certain that the particulars o f a problem do n o t override its commonalities with o t h e r p ro b - lems already dealt with.

The conditions in a city constructing a subway m a y l o o k similar to the conditions in San Francisco, say; b u t planners would be ill-advised to transfer the San Francisco solutions directly. Differences in c o m m u t e r habits o r residential patterns m a y far outweigh similarities in subway layout, d o w n t o w n layout a n d the rest. In the more complex world o f social policy planning, every situation is likely to be one-of-a-kind. I f we are right a b o u t that, the direct transference o f the physical-science a n d engineer- ing thoughtways into social policy might be dysfunctional, i.e. positively harmful. " S o l u t i o n s " might be applied to seemingly familiar problems which are quite in- c o m p a t i N e with them.

8. Every wicked problem can be considered t o be a symptom o f another problem

Problems can be described as discrepancies between the state o f affairs as it is and the state as it ought to be. The process o f resolving the problem starts with the search for causal explanation o f the discrepancy. R e m o v a l o f t h a t cause poses a n o t h e r problem o f which the original problem is a " s y m p t o m . " In turn, it can be considered the s y m p t o m o f still another, "higher level" problem. Thus "c ri me in the streets" can be considered as a symptom o f general moral decay, or permissiveness, o r deficient opportunity, or wealth, or poverty, or whatever causal explanation y o u h a p p e n to like best. The level at which a problem is settled depends u p o n the self-confidence o f the analyst and cannot be decided on logical grounds. There is nothing like a natural level o f a wicked problem. O f course, the higher the level o f a problem's fo rmu l a t i o n , the b r o a d e r and more general it becomes: and the more difficult it becomes to d o something a b o u t it. On the other hand, one should n o t t ry to cure symptoms: a n d therefore one should try to settle the p r o b l e m on as high a level as possible.

Here lies a difficulty with incrementalism, as well. This doctrine advertises a policy o f small steps, in the hope o f contributing systematically to overall improvement. If, however, the problem is attacked on t o o low a level (an increment), t h e n success o f resolution may result in making things worse, because it m a y become mo re difficult to deal with the higher problems. Marginal i mp ro v e me n t does n o t guarantee overall improvement. F o r example, computerization o f an administrative process m a y result in reduced cost, ease o f operation, etc. Bu t at the same time it becomes more difficult to incur structural changes in the organization, because technical perfection reinforces organizational patterns and normally increases the cost o f change. The newly acquired power o f the controllers o f i n f o r m a t i o n m a y then deter later modifications o f their roles.

U n d e r these circumstances it is not surprising tha t the members o f an organization tend t o see the problems on a level below their own level. I f y o u ask a police chief what the problems o f the police are, he is likely to d e m a n d better hardware.

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9. The existence o f a discrepancy representing a wicked problem can be explained in numerous ways. The choice o f explanation determines the nature o f the problem's resolution

" C r i m e in the streets" can be explained by n o t enough police, b y t o o many criminals, b y inadequate laws, too m a n y police, cultural deprivation, deficient opportunity, too m a n y guns, phrenologic aberrations, etc. Each o f these offers a direction for attacking crime in the streets. Which one is right ? There is no rule o r procedure to determine the " c o r r e c t " explanation o r combination o f them. Th e reason is that in dealing with wicked problems there are several mo re ways o f refuting a hypothesis t h a n there are permissible in the sciences.

The mode o f dealing with conflicting evidence that is customary in science is as follows: " U n d e r conditions C and assuming the validity o f hypothesis H , effect E must occur. Now, given C, E does not occur. Consequently H is to be re fu t e d ." In the context o f wicked problems, however, further modes are admissible: one can deny that the effect E has not occurred, or one can explain the nonoccurrence o f E b y intervening processes without having to a b a n d o n H. Here's an example: Assume that somebody chooses to explain crime in the streets b y " n o t enough police." This is made the basis o f a plan, and the size o f the police force is increased. Assume fu rt h e r that in the subsequent years there is an increased n u m b e r o f arrests, but an increase o f offenses at a rate slightly lower than the increase o f G N P . Has the effect E occurred ? Has crime in the streets been reduced by increasing the police f o r c e ? I f the answer is no, several nonscientific explanations m a y be tried in order to rescue the hypothesis H ("Increasing the police force reduces crime in the streets"): " I f we had n o t increased the n u m b e r o f officers, the increase in crime would have been even greater; . . . . This case is an exception f r o m rule H because there was an irregular influx o f criminal elements; . . . . Time is t o o short to feel the effects y e t ; " etc. But also the answer "Yes, E has o c c u r r e d " can be defended: " T h e n u m b e r o f arrests was increased," etc.

In dealing with wicked problems, the modes o f reasoning used in the argument are m u c h richer t h a n those permissible in the scientific discourse. Because o f the essential uniqueness o f the problem (see Proposition 7) and lacking o p p o r t u n i t y f o r rigorous experimentation (see Proposition 5), it is n o t possible to p u t H to a crucial test.

T h a t is to say, the choice o f explanation is arbitrary in the logical sense. In actuality, attitudinal criteria guide the choice. People choose those explanations which are most plausible to them. Somewhat but not much exaggerated, y o u might say that everybody picks that explanation of a discrepancy which fits his intentions best and which conforms to the action-prospects that are available to him. Th e analyst's " w o r l d view" is the strongest determining factor in explaining a discrepancy and, therefore, in resolving a wicked problem.

10. The planner has no right to be wrong

As Karl P o p p e r argues in The Logic of Scientific Discovery,4 it is a principle o f science that solutions to problems are only hypotheses offered for refutation. This

4 Science Editions, New York, 1961.

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habit is based on the insight that there are no proofs to hypotheses, only potential refutations. The more a hypothesis withstands numerous attempts at refutation, the better its " c o r r o b o r a t i o n " is considered to be. Consequently, the scientific c o m m u n i t y does n o t blame its members for postulating hypotheses that are later r e f u t e d - s o long as the a u t h o r abides by the rules o f the game, o f course.

In the world o f planning and wicked problems no such i mmu n i t y is tolerated. H e re the aim is not to find the truth, but to improve some characteristics o f the w o rl d where people live. Planners are liable for the consequences o f the actions they generate; the effects can matter a great deal to those people t h a t are t o u c h e d b y those actions.

We are thus led to conclude that the problems t h a t planners mu st deal with are wicked and incorrigible ones, for they defy efforts to delineate their boundaries a n d to identify their causes, and thus to expose their problematic nature. Th e planner w h o works with open systems is caught up in the ambiguity o f their causal webs. M o re o v e r, his would-be solutions are confounded by a still further set o f dilemmas posed by the growing pluralism o f the c o n t e m p o r a r y publics, whose valuations o f his proposals are judged against an a r r a y o f different and contradicting scales. Let us t u r n to these dilemmas next.

IV. The Social Context

There was a time during the 'Fifties when the quasi-sociological literature was pre- dicting a Mass Society--foreseen as a rather homogeneously shared culture in which most persons would share values and beliefs, would h o l d to c o m m o n aims, would follow similar life-styles, and thus would behave in similar ways. (You will recall the p o p u l a r literature on suburbia o f ten years ago.) It is now a p p a re n t t h a t those fore- casts were wrong.

Instead, the high-scale societies o f the Western world are becoming increasingly heterogeneous. They are becoming increasingly differentiated, comprising thousands o f minority groups, each joined a r o u n d c o m m o n interests, c o m m o n value systems, and shared stylistic preferences that differ f r o m those o f o t h e r groups. As the sheer volume of information and knowledge increases, as] technological developments further expand the range o f options, and as awareness o f the liberty to deviate a n d differentiate spreads, m o r e variations are possible. Rising atttuence or, even more, growing desire for at least subcultural identity induces groups t o exploit those options and to invent new ones. We almost dare say that irregular cultural permutations are becoming the rule. We have come to realize that the melting p o t never w o r k e d f o r large numbers o f immigrants to America,5 and that the unitary conception o f "'The American W a y o f Life" is now giving way to a recognition that there are n u me ro u s ways o f life that are also American.

It was pre-industrial society that was culturally homogeneous. T h e industrial age greatly expanded cultural diversity. Post-industrial society is likely to be far m o r e differentiated t h a n any in all o f past history.

It is still too early to know whether the current politicization o f subpublics is

5 See an early sign of this growing realization in Nathan Glazer and Daniel Patrick Moynihan, Beyond the Melting Pot (Cambridge: Harvard and MIT Presses, 1963).

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going t o be a long-run p h e n o m e n o n or not. One could write scenarios t h a t would b e equally plausible either way. But one thing is clear: large p o p u l a t i o n size will m e a n t h a t small minorities can comprise large n u m b e r s o f people; and, as we have been seeing, even small minorities can swing large political influence.

I n a setting in which a plurality o f publics is politically pursuing a diversity o f goals, h o w is the larger society to deal with its wicked p r o b l e m s in a planful way ? H o w are goals to be set, when the valuative bases are so diverse ? Surely a unitary conception o f a unitary "public welfare" is an anachronistic one.

W e d o n o t even have a t h e o r y t h a t tells us h o w to find o u t what m i g h t be considered a societally best state. We have n o t h e o r y t h a t tells us w h a t distribution o f the social p r o d u c t is b e s t - - w h e t h e r those o u t p u t s are expressed in the coinage o f m o n e y income, i n f o r m a t i o n income, cultural opportunities, o r whatever. We h a v e c o m e to realize t h a t the concept o f the social p r o d u c t is n o t very meaningful; possibly there is no aggregate m e a s u r e f o r the welfare o f a highly diversified society, if this measure is claimed to be objective a n d non-partisan. Social science has simply been unable to uncover a social-welfare function t h a t would suggest which decisions would contri- b u t e to a societally best state. Instead, we have h a d to rely u p o n the a x i o m s o f in- dividualism t h a t underlie economic a n d political theory, deducing, in effect, t h a t the larger-public welfare derives f r o m s u m m a t i o n o f individualistic choices. A n d yet, we k n o w t h a t this is n o t necessarily so, as o u r current experience with air pollution has dramatized.

W e also k n o w t h a t m a n y societal processes have the character o f z e r o - s u m games. As the p o p u l a t i o n becomes increasingly pluralistic, inter-group differences are likely to be reflected as inter-group rivalries o f the zero-sum sorts. I f they do, the prospects f o r inventing positive n o n - z e r o - s u m d e v e l o p m e n t strategies would become increasingly difficult.

P e r h a p s we can illustrate. A few years ago there was a nearly universal consensus in A m e r i c a t h a t full-employment, high productivity, a n d widespread distribution o f c o n s u m e r durables fitted into a d e v e l o p m e n t strategy in which all would be winners. T h a t consensus is n o w being eroded. N o w , when substitutes for wages are being disbursed t o the p o o r , the college student, a n d the retired, as well as to the m o r e traditional recipient o f nonwage incomes, o u r conceptions o f " e m p l o y m e n t " and o f a f u l l - e m p l o y m e n t e c o n o m y are h a v i n g t o be revised. N o w , when it is recognized t h a t r a w materials t h a t enter the e c o n o m y end u p as residuals polluting the air mantle a n d the rivers, m a n y are b e c o m i n g w a r y o f rising m a n u f a c t u r i n g production. And, w h e n some o f the new middle-class religions are exorcising worldly goods in f a v o r o f less tangible c o m m u n a l " g o o d s , " the c o n s u m p t i o n - o r i e n t e d society is being chal- l e n g e d - o d d l y enough, to be sure, b y those who were reared in its affluence.

W h a t was once a clear-cut win-win strategy, that h a d the status o f a near-truism, has n o w b e c o m e a source o f contentious differences a m o n g subpublics.

Or, i f these illustrations seem to be p o s e d at t o o high a level o f generality, consider the sorts o f inter-group conflicts i m b e d d e d in u r b a n renewal, r o a d w a y construction, or curriculum design in the public schools. O u r o b s e r v a t i o n is not only that values are changing. T h a t is true enough, a n d the probabilities o f p a r a m e t r i c changes are large enough to h u m b l e even the m o s t perceptive observer o f c o n t e m p o r a r y norms.

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O u r point, rather, is that diverse values are held by different groups o f i n d i v i d u a l s - - that what satisfies one m a y be a b h o r r e n t to another, that what comprises problem- solution f o r one is problem-generation for another. U n d e r such circumstances, and in the absence o f an overriding social t h e o r y or an overriding social ethic, there is n o gainsaying which group is right and which should have its ends served.

One traditional a p p r o a c h to the reconciliation o f social values a n d individual choice is to entrust de facto decision-making to the wise a n d knowledgeable professional experts and politicians. But whether one finds that ethically tolerable or not, we hope we have made it clear that even such a tactic only begs the question, t b r there are no value-free, true-false answers to any o f the wicked problems governments must deal with. T o substitute expert professional j u d g m e n t fo r those o f contending political groups m a y make the rationales and the repercussions m o r e explicit, b u t it would not necessarily make the outcomes better. The one-best answer is possible with tame problems, but not with wicked ones.

A n o t h e r traditional a p p r o a c h to the reconciliation o f social values a n d individual choice is to bias in favor o f the latter. Accordingly, one would p r o m o t e widened differentiation o f goods, services, environments, a n d opportunities, such t h a t indivi- duals might m o r e closely satisfy their individual preferences. Wh e re large-system problems are generated, he would seek to ameliorate the effects t h a t he judges mo st deleterious. Where latent opportunities become visible, he would seek t o exploit them. Where positive non-zero-sum developmental strategies can be designed, he would o f course work hard to install them.

Whichever the tactic, though, it should be clear t h a t the expert is also the player in a political game, seeking to p r o m o t e his private vision o f goodness over others'. Planning is a c o m p o n e n t o f politics. There is no escaping t h a t truism.

We are also suggesting that none o f these tactics will answer the difficult questions attached to the sorts o f wicked problems planners must deal with. We have neither a theory that can locate societal goodness, n o r one that might dispel wickedness, n o r one that might resolve the problems o f equity that rising pluralism is provoking. We are inclined to think that these theoretic dilemmas m a y be the most wicked conditions that confront us.

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