Representation of subjective preferences under ambiguity

The objective of this paper is to show how potentially incomplete preferences of a decision maker (DM) on acts can be modelled formally in a subjective ambiguity perspective. We identify acts as functions from a state space Ω to bounded support (finitely additive) probabilities over a set X of prizes. Then, we characterize preferences over equibounded acts a which have a numerical representation by the family of functionals , where u is a cardinal utility on X (representing the risk attitude of the DM) and Π is a unique pointwise closed convex set of probabilities on all events in Ω (representing the ambiguity perceived by the DM). To this end, in addition to the usual independence and continuity assumptions, we add completeness and dominance for preferences restricted to constant acts; moreover, we consider two other properties (subjective monotonicity and coherence) related with the preferences of a DM who is not able, owing to his partial knowledge, to evaluate any event in Ω.     

On Empty Compliments and Deceptive Detours A Neopragmatist Response to Theodore W. Nunez

The philosophical question Nunez raises is whether we can have, as he thinks we need, a theoretical grounding for appeal to the intrinsic value of nature. This article examines the neopragmatist reasons for repudiating metaphysical realism's notions of intrinsicality and subject-independent reality. Following the holism of Donald Davidson and Richard Rorty rather than the epistemological premises of Holmes Rolston and Bernard Lonergan, the author concludes that coping with the ecological crisis does not require conjuring an epistemic crisis. Environmental ethics in neopragmatist hands would seek procedures for bringing about agreement in improving our practices, not our epistemology.     

Chisholm's Epistemic Principles

Abstract: An exposition and discussion of Chisholm's “epistemic principles.” These are compared with relevant views of Wilfrid Sellars and Richard Foley. A further comparison, with the approach favored by Descartes, is argued to throw light on the status of such principles.     

Memory of Past Beliefs and Actions

Two notions of memory are studied both syntactically and semantically: memory of past beliefs and memory of past actions. The analysis is carried out in a basic temporal logic framework enriched with beliefs and actions.     

Distortion of probability and outcome information in risky decisions

Substantial evidence indicates that information is distorted during decision making, but very few studies have assessed the distortion of probability and outcome information in risky decisions. In two studies involving six binary decisions (e.g., banning blood donations from people who have visited England, because of “mad cow disease”), student and nonstudent participants distorted their evaluations of probability and outcome information in the direction of their preferred decision alternative and used these biased evaluations to update their preferences. Participants also evaluated the utilities of possible outcomes more positively when the outcomes could follow only from the preferred alternative and more negatively when they could follow only from the competing alternative. Such circular reasoning is antithetical to the normative consequentialist principles underlying decision analysis. Presenting numerical information as precise values or as ranges of values did not significantly affect information distortion, apparently because the manipulation did not affect perceived ambiguity as intended.     

PHILOSOPHERS OF INTELLECTUAL DISABILITY: A TAXONOMY

Abstract: This essay explores various roles that philosophers occupy in relation to intellectual disability. In examining how philosophers define their object of inquiry as experts and gatekeepers, it raises critical questions concerning the nature of philosophical discourse about intellectual disability. It then goes on to consider three alternate positions, the advocate or friend, the animal, and the "intellectually disabled," each of which points to new ways of philosophizing in the face of intellectual disability.     

Projective expected utility

Motivated by several classic decision-theoretic paradoxes, and by analogies with the paradoxes which in physics motivated the development of quantum mechanics, we introduce a projective generalization of expected utility along the lines of the quantum-mechanical generalization of probability theory. The resulting decision theory accommodates the dominant paradoxes, while retaining significant simplicity and tractability. In particular, every finite game within this larger class of preferences still has an equilibrium.     

Decomposition,Interdependence and Precision in Multiattribute Utility Measurements

Traditionally, parameters of multiattribute utility models, representing a decision maker's preference judgements, are treated deterministically. This may be unrealistic, because assessment of such parameters is potentially fraught with imprecisions and errors. We thus treat such parameters as stochastic and investigate how their associated imprecision/errors are propagated in an additive multiattribute utility function in terms of the aggregate variance. Both a no information and a rank order case regarding the attribute weights are considered, assuming a uniform distribution over the feasible region of attribute weights constrained by the respective information assumption. In general, as the number of attributes increases, the variance of the aggregate utility in both cases decreases and approaches the same limit, which depends only on the variances as well as the correlations among the single-attribute utilities. However, the marginal change in aggregate utility variance decreases rather rapidly and hence decomposition as a variance reduction mechanism is generally useful but becomes relatively ineffective if the number of attributes exceed about 10. Moreover, it was found that utilities which are positively correlated increase the aggregate utility variance, hence every effort should be made to avoid positive correlations between the single-attribute utilities. We also provide guidelines for determining under what condition and to what extent a decision maker should decompose to obtain an aggregate utility variance that is smaller than that of holistic assessments. Extensions of the current model and empirical research to support some of our behavioural assumptions are discussed. © 1997 John Wiley & Sons, Ltd.     

A simple trade-off condition for additive multiattribute utility

We show that only two simple trade-off judgments are sufficient to determine whether the multiplicative multiattribute model assumes its additive form, regardless of the number of attributes in the model. This additivity condition offers a useful alternative to the test based on multiattribute lotteries commonly presented in textbooks. It can make the determination of additivity easier and more reliable. © 1997 John Wiley & Sons, Ltd.