Sven Ove Hansson

Although choice and preference are distinct categories, it may in some contexts be a useful idealization to treat choices as fully determined by preferences. In order to construct a general model of such preference-based choice, a method to derive choices from preferences is needed that yields reasonable outcomes for all preference relations, even those that are incomplete and contain cycles. A generalized choice function is introduced for this purpose. It is axiomatically characterized and is shown to compare favourably with alternative constructions.

Several attempts have been made to transfer the concept of informed consent from medical and research ethics to dealing with affected groups in other areas such as engineering, land use planning, and business management. It is argued that these attempts are unsuccessful since the concept of informed consent is inadequate for situations in which groups of affected persons are dealt with collectively (rather than individually, as in clinical medicine). There are several reasons for this. The affected groups from which informed consent is sought cannot be identified with sufficient precision. Informed consent is associated with individual veto power, but it does not appear realistic to give veto power to all individuals who are affected for instance by an engineering project. Most importantly, the concept of informed consent puts focus on the public’s acceptance of ready-made proposals rather than on its participation in the decision-making process as a whole, which includes the development of alternatives for the decision. Therefore, the concept of informed consent is not applicable to a company’s relations with groups and collectives. It may, however, be applicable to a company’s relations with individual persons such as customers and employees.

Den moralfilosofiska traditionen har sina begränsningar. De frågor som stått i centrum för den moralfilosofiska diskussionen har ofta varit helt andra än de som människor i det praktiska livet har uppfattat som centrala moraliska problem. En viktig begränsning är att moralfilosofin, liksom beslutsteorin, nästan uteslutande har handlat om hur man hanterar välavgränsade problem där handlingsalternativen är givna. I det verkliga livet löser vi ofta moraliska problem genom att finna på nya handlingsalternativ, som inte fanns med från början.1 En annan begränsning är att moralfilosofin till allra största delen har handlat om situationer där konsekvensen av de olika handlingsalternativen är välkänd. I det praktiska livet är det annorlunda. Vi vet sällan med säkerhet vad som kommer att bli följden av de olika alternativ som vi väljer mellan. Man kan också uttrycka detta så att moralfilosofin i huvudsak rör sig i en tänkt deterministisk värld, där man inte behöver räkna med någon slump. Detta är aningen märkligt mot bakgrund av det oerhörda genomslag som sannolikhetstänkande och på senare år även kaos har fått inom andra vetenskapsområden. Det finns naturligtvis förklaringar till detta moralfilosofins kvardröjande i en äldre världsbild. Redan i det deterministiska fallet uppstår svårhanterliga problem som man gärna ger sin odelade uppmärksamhet. Dessutom finns det en särskild disciplin, beslutsteorin, som behandlar beslut under risk och osäkerhet. Man har i allmänhet tänkt sig ett slags arbetsfördelning, där problemen med risk och osäkerhet utelämnas i moralfilosofin för att i stället hanteras inom beslutsteorin med rena rationalitetsprinciper (dvs. utan att moraliska principer är inblandade). Enligt min mening är denna arbetsfördelning inte hållbar. Betrakta t ex osäkerheten om hur klimatet kommer att förändras med nuvarande utsläppstrender för växthusgaser. Denna osäkerhet ger upphov inte enbart till ett problem om rationellt beslutsfattande utan också till moraliska problem..

Two of the major problems in AGM-style belief revision, namely the difficulties in accounting for iterated change and for Ramsey test conditionals, have satisfactory solutions in descriptor revision. In descriptor revision, the input is a metalinguistic sentence specifying the success condition of the operation. The choice mechanism selects one of the potential outcomes in which the success condition is satisfied. Iteration of this operation is unproblematic. Ramsey test conditionals can be introduced without giving rise to the paradoxical results that they generate in other systems. In addition to standard Ramsey test conditionals, a more general variant of epistemic conditionals is defined, representing statements of the form ”if the belief state is changed to satisfy condition A then it will satisfy condition B”. An axiomatic characterization of such descriptor conditionals is presented. It is related in intricate ways to the KLM postulates for cumulative reasoning.

Multiple contraction (simultaneous contraction by several sentences) and iterated contraction are investigated in the framework of specified meet contraction (s.m.c.) that is extended for this purpose. Multiple contraction is axiomatized, and so is finitely multiple contraction (contraction by a finite set of sentences). Two ways to reduce finitely multiple contraction to contraction by single sentences are introduced. The reduced operations are axiomatically characterized and their properties are investigated. Furthermore, it is shown how iterated contraction can be reduced to single-step, single-sentence contraction. However, in this framework the outcome of iterated contraction depends unavoidably on the order in which the inputs are received. This order-dependence makes it impossible to treat two inputs on an equal footing. Therefore it is often preferable to perform changes involving several pieces of information as multiple rather than iterated change.

An agent can usually hold a very large number of beliefs. However, only a small part of these beliefs is used at a time. Efficient operations for belief change should affect the beliefs of the agent locally, that is, the changes should be performed only in the relevant part of the belief state. In this paper we define a local consequence operator that only considers the relevant part of a belief base. This operator is used to define local versions of the operations for belief change. Representation theorems are given for the local operators.

Generalizations of partial meet contraction are introduced that start out from the observation that only some of the logically closed subsets of the original belief set are at all viable as contraction outcomes. Belief contraction should proceed by selection among these viable options. Several contraction operators that are based on such selection mechanisms are introduced and then axiomatically characterized. These constructions are more general than the belief base approach. It is shown that partial meet contraction is exactly characterized by adding to one of these constructions the condition that all logically closed subsets of the belief set can be obtained as the outcome of a single (multiple) contraction. Examples are provided showing the counter-intuitive consequences of that condition, thus confirming the credibility of the proposed generalization of the AGM framework

The ideal world semantics of standard deontic logic identifies our obligations with how we would act in an ideal world. However, to act as if one lived in an ideal world is bad moral advice, associated with wishful thinking rather than well-considered moral deliberation. Ideal world semantics gives rise to implausible logical principles, and the metaphysical arguments that have been put forward in its favour turn out to be based on a too limited view of truth-functional representation. It is argued that ideal world semantics should be given up in favour of other, more plausible uses of possible worlds for modelling normative subject-matter.