They argue that their intention is not to describe

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Unformatted text preview: ably evokes anxiety.” Additional limitations on maximising behaviour become apparent in considering the human predicament of decision-making. Shackle (1974 p1) eloquently articulates this in the following quote: 190 “If choice is originative, it can be effective, it can give thrust to the course of things intended to secure its ends. In order to secure its ends, choice must apply a knowledge of what will be the consequence of what. But the sequel of an action chosen by one man will be shaped by circumstance, and its circumstances will include the actions chosen now and actions to be chosen in time to come by other men. If, therefore, choice is effective, it is unpredictable and thus defeats, in some degree, the power of choice itself to secure exact ends. This is the human predicament…Decision is not, in its ultimate nature, calculation, but origination.” If, as Shackle indicates, decision-making is not founded on calculation, the assumptions underlying decision analysis are untenable. As such Tocher and other opponents would rather operate with no model at all than utilise a model that is in conflict with how people actually act and think: “…any theory which is worth using predicts how people will behave, not how they should, so we can do our mathematics.” (Tocher, 1976 reprinted in French, 1989 p140) Decision analysts response to such criticisms is that they acknowledge that utility functions and subjective probability distributions do not provide valid models of decision-maker’s actual preferences and beliefs (French, 1989). They argue that their intention is not to describe the decision-maker’s beliefs and preferences as they are; it is to suggest what they ought to be, if the decision-maker wishes to be consistent. French urges that the “is” should not be confused with the “ought”, and decision analysis only suggests how people ought to choose. Decision analysis, he argues, is normative not descriptive analysis. Keeney and Raiffa (1976 pvii) adopt a similar stance: “…[decision analysis is a] prescriptive approach designed for normally intelligent people who want to think hard and systematically about important real problems.” Krantz et al. (1971) describe decision analysis to be: “…normative principles defining the concept of rational behaviour rather than a description of actual behaviour”. (cited by Tocher, 1978 reprinted in French, 1989 p151) They go on to say: “…We want to stress that subjective probabilities are means of describing rational behaviour. Nothing more! They cannot be used as estimates of the 191 objective probability of an event or the credibility of a statement or the corroboration of a theory.” (cited by Tocher, 1978 reprinted in French, 1989 p151) But to critics such as Tocher such a defence is weak and referring to the above quote from Krantz, Tocher writes: “This sums up my attitude to the utilitarians; I am irritated by their arrogance – they will tell me how I ought to think regardless of the evidence of how people actually think or take decisi...
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