DISCUSSION 23

Third, the analyst would encourage all the par-ticipants to express any sense of unease about anyaspect of the analysis as soon as it arises. Explor-ing the sense of unease through introspection,talking to others, gathering data, considering pos-sible future scenarios, role playing, decision simu-lation, outcome psychodrama, or any otherapproach, could, as Wright and Goodwin help-fully suggest, deepen understanding of the issuesas well as clarify values. Wooler and Erlich foundthat their managers often did not like the firstanalysis and came back for two or three moresessions before they began to feel comfortablewith the results of the modelling. Developing arequisite model requires iteration.

Finally, rather than passively evaluating op-tions against criteria, as in conventional decisionanalysis, the decision maker would be encouragedto take a proactive stance. The model can be usedto ‘explore the future without having to live it’ asone decision conference participant put it. Bytrying different values and weights, seeing whatassessments affect the overall preferences, and

which do not, the decision maker gains a clearerview of what matters and of what may requirefurther work. Then, even without precise valuesthe model can serve as a guide to construct thedesired job, to negotiate the terms that will bestsatisfy the decision maker’s values as they are atthe time of the decision. This is the generative useof decision modelling, and I would bet that ifJoseph Priestly had been assisted in developing atruly requisite decision model, he might have ac-cepted Lord Shelburne’s offer in the first place.

REFERENCES

Phillips, L.D., ‘A theory of requisite decision models’,Acta Psychol., 56, 29–48 (1984).

Wooler, S. and Erlich, A., ‘Independence betweenproblem structuring and attribute weighting in transi-tional decision problems’, in Humphreys, P., Sven-son, O. and Vari, A. (eds), Analysing and AidingDecision Processes, Amsterdam, North Holland,1982.

Comment by Thomas L. Saaty

The paper by Wright and Goodwin makes severalgood points with which I am in total agreement,particularly about the need for scenarios and for acreative approach in laying out a decision prob-lem. I am concerned that the mathematics theyuse gets compromised in ways that I consider toogallant. If I were in their place, I would look atthe entire problem including the methodologythey assume to be unique and irrevocable, andquestion why one has to accept its axioms andassumptions. We are free to create a picture of aworld that serves our needs and interests. Whyshould we assume that other people know better,particularly when their knowledge leads us intoseemingly irresolvable problems, and prevent usfrom asking questions about potential thinkingand procedures not addressable in that approach?For example, if the authors allow for dependenceand feedback in their thought framework, theycould derive importance weights for the at-tributes, not a priori, although in some problemsthat may be the case, but in terms of the alterna-tives. I am aware that utility theory does not

allow that, and argumentatively insist that it can-not be done, but why not? Suppose the alterna-tives are to select the best among three and onlythree candidates for a teacher. Assume that onewants to make the best of a bad lot so one has tolook at the candidates to see what they each haveto offer and then determine who is best, overall. Itseems to me that one can ask ‘is candidate Abetter at music or at maths and how much betterat one than the other?’ One does this sort ofevaluation in real life all the time. The result isthat in this case the attributes inherit their impor-tance from the alternatives and the alternatives inturn from the attributes and we have a feedbackevaluation process. Now if the alternatives aremeasured on an interval scale, one cannot usethese utility values to carry out feedback becausenumbers that belong to an interval scale used inutility theory cannot be added except under re-strictive circumstances. What is extremely limitingis that they cannot be used to weight other num-bers and carry out feedback. The fact that theauthors choose to limit their thinking because of

Copyright © 1999 John Wiley & Sons, Ltd. J. Multi-Crit. Decis. Anal. 8: 11–27 (1999)

DISCUSSION24

such restrictions does not mean that our thoughtprocesses are stuck. If they allow ratio scalesthroughout the evaluation process things wouldlook very different and most of the problemsthey talk about would dim in importance. I maybe wrong, but I feel that there is religion in thiswhole business and of course there is only onereligion that is presumably right and rational andfree of paradoxes (see the work of Allais and hisNobel prize), and that is utility theory. If onewere to be scientific about it, one would see thatthe rules and inventions we impose on ourselvestoday will not look rational and mandatoryforever. To make good decisions, we need to bemore descriptive and less normative. Look atwhat utility practitioners do. One of the basicassumptions in utility theory is that the alterna-tives must be independent of each other. Themoment one knows them all even in one’s mindthey are no longer independent and if they aredependent then anything can happen in rankingthem. Yet they blindly assume the poorest ver-sion, the fourth of four (see Luce and Raiffa and

what they say) of the rank preservation ax-iomatic formulations! Is that good science?

I am also a little concerned that too muchchit-chat about values sometimes forces peopleto accept things which after walking out of theroom they find questionable. One should notunderestimate the fact that we all have our owncharacteristic preferences and likes and dislikesthat do not disappear on command or at thebehest of momentary rationality. We are like arubber band that is most comfortable and natu-ral when not too stressed, whatever the reasonmay be. Discussion is important and scenariosare even more important. The question is howmuch difference they make to a particular deci-sion maker. If such ideas actually work, why dotheir advocates not try them out in a mundaneway, for example making a million dollars in thestock market by appropriate choice of scenariosand risk attitude? Really, why not. I would settlefor a much smaller amount if I were sure theywould work every time or even nearly everytime!

Comment by Bertram Schoner, Eng Ung Choo andWilliam C. Wedley

VALUES—WHAT IS THE SOLUTION?

We are members of a small school of AHP revi-sionists who find common ground in believing thestandard AHP model flawed but repairable, withmodest agreement on how to fix it. Most AHPresearchers presume that decision makers are ex-plicitly aware of their values, and are capable ofperforming pairwise comparisons of alternativesand criteria. We are grateful to Wright and Good-win for sparking some serious thinking (at leaston our part) on how values fit into the largerAHP framework.

Clearly, the values of the decision maker arecentral in any significant decision problem. Valuesconstitute a determinant of the alternatives to beconsidered, determine the salient attributes/crite-ria under which alternatives are to be evaluated,and underlie the relative preference for alterna-tives on each attribute.

Wright and Goodwin claim that values may bechangeable or even unformed, and straightfor-ward decision analysis breaks down under thesecircumstances. They illustrate the problem by dis-cussing the application of decision analytic tech-niques to the problem of a career move that hadbeen considered by one of them (DM). (Like DM,one of us was also recently faced with a careerchoice decision. In a rare capitulation to his rightbrain, he made the decision intuitively.)

Keeney (1992) indicates that the first stage ofthe decision problem, even before investigatingcriteria or alternatives, should involve the identifi-cation of values. But even when implicit andunreflective (as is generally the case in the multi-criteria decisions) values perform as if they werearticulated (Williams, 1979). Values enter into theproblem at both the problem definition and evalu-ation stages in the decision process. At the prob-lem definition stage they define the criteria to be

Copyright © 1999 John Wiley & Sons, Ltd. J. Multi-Crit. Decis. Anal. 8: 11–27 (1999)