Multiple and iterated contraction reduced to single-step single-sentence contraction

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.     

Coherence in Epistemology and Belief Revision*

A general theory of coherence is proposed, in which systemic and relational coherence are shown to be interdefinable. When this theory is applied to sets of sentences, it turns out that logical closure obscures the distinctions that are needed for a meaningful analysis of coherence. It is concluded that references to “all beliefs” in coherentist phrases such as “all beliefs support each other” have to be modified so that merely derived beliefs are excluded. Therefore, in order to avoid absurd conclusions, coherentists have to accept a weak version of epistemic priority, that sorts out merely derived beliefs. Furthermore, it is shown that in belief revision theory, coherence cannot be adequately represented by logical closure, but has to be represented separately. *Contribution to “Seven Bridges”     

The Modes of Value

Contrary to the received view, decision theory is not primarily devoted to instrumental (ends-to-means) reasoning. Instead, its major preoccupation is the derivation of ends from other ends. Given preferences over basic alternatives, it constructs preferences over alternatives that have been modified through the addition of value object modifiers (modes) that specify probability, uncertainty, distance in time etc. A typology of the decision-theoretical modes is offered. The modes do not have (even extrinsic) value, but they transform the value of objects to which they are applied. A rational agent's total set of preferences should be coherent, but from this it does not follow that her preferences over mode-containing objects have to be derivable from her preferences over mode-free objects.     

Genetic probes of three theories of maternal adjustment: I. Recent evidence and a model.

Studies focusing on genetic and social influences on maternal adjustment will illumine mother's marriage, parenting, and the development of psychopathology in her children. Recent behavioral genetic research suggests mechanisms by which genetic and social influences determine psychological development and adjustment. First, heritable, personal attributes may influence individuals' relationships with their family members. These genetically influenced family patterns may amplify the effects of adverse, heritable personal attributes on adjustment. Second, influences unique to siblings may be the most important environmental determinants of adjustment. We derive three hypotheses on maternal adjustment from integrating these findings from genetic studies with other contemporary research on maternal adjustment. First, mother's marriage mediates the influence of her heritable, personal attributes on her adjustment. Second, mother's recall of how she was parented is partially genetically influenced, and both her relationships with her spouse and her child mediate the impact of these genetically influenced representations on her current adjustment. Third, characteristics of mother's spouse are important influences on difference between her adjustment and that of her sister's. These sibling-specific influences are unrelated to mother's heritable attributes. The current article develops this model, and [figure: see text] the companion article describes the Twin Mom Study that was designed to test it as well, as its first findings. Data from this study can illumine the role of family process in the expression of genetic influence and lead to specific family interventions designed to offset adverse genetic influences.     

Genetic probes of three theories of maternal adjustment: II. Genetic and environmental influences.

This is the first report of the Twin Mom Study, an investigation of three hypotheses concerning influences on maternal adjustment. These hypotheses concern the role of the marital and parent-child relationships in mediating genetic influences on maternal adjustment and on the importance of the mothers' marital partners as a specifiable source of influences on their adjustment not shared with their sisters. The study's sample of 150 monozygotic (MZ) twins and 176 dizygotic (DZ) twins was drawn randomly from the Swedish Twin Registry and is, with some small exceptions, likely to be representative of women in the Swedish population. The sample included the marital partners of these twins and their adolescent children. Self-report and coded videotapes were a source of information about family process. Results reported in this first report focus on comparability of American and Swedish samples on scales measuring psychiatric symptoms, and on an analysis of genetic and environmental influences on nine measures of mothers' adjustment. Results suggest comparability between the US and Sweden. Genetic influences were found for all measures of adjustment, particularly in the psychological manifestations of anxiety and for smoking. The pattern of findings also underscored the importance of influences unique to each sibling within the twin pair, thus focusing attention on the potential role of marital partners in maternal adjustment. Results also suggested that experiences shared by the twin sisters, experiences unrelated to their genetic similarity, may influence their fearfulness and alcohol consumption. Our model did not include these influences and thus must be amended.     

A new semantical approach to the logic of preference

A possible world semantics for preference is developed. The remainder operator () is used to give precision to the notion that two states of the world are as similar as possible, given a specified difference between them. A general structure is introduced for preference relations between states of affairs, and three types of such preference relations are defined. It is argued that one of them, actual preference, corresponds closely to the concept of preference in informal discourse. Its logical properties are studied and shown to be plausible.     

Protecting people in research: a comparison between biomedical and traffic research

Traffic research shares a fundamental dilemma with other areas of empirical research in which humans are potentially put at risk. Research is justified because it can improve safety in the long run. Nevertheless, people can be harmed in the research situation. Hence, we need to balance short-term risks against long-term safety improvements, much as in other areas of research with human subjects. In this paper we focus on ethical issues that arise when human beings are directly affected in the performance of research by examining how the ethical requirements in biomedical research can inform traffic research. After introducing the basic ethical requirements on biomedical research, each of the major requirements is discussed in relation to traffic research. We identify the main areas where biomedical research and traffic research differ, and where the ethical requirements from the former cannot easily be transferred to the latter. Finally, we argue that there is a need for systematic studies of the ethics of traffic research and point to some of the issues that need to be addressed.     

Preference-based choice functions: a generalized approach

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.     

The Endurance/Perdurance Controversy is No Storm in a Teacup

Several philosophers have maintained in recent years that the endurance/perdurance debate is merely verbal: these prima facie distinct theories of objects’ persistence are in fact metaphysically equivalent, they claim. The present paper challenges this view. Three proposed translation schemes (those set forth by Miller in Erkenntnis 62:91–117, 2005, McCall and Lowe in Noûs 40:570–578, 2006, and Hirsch in Metametaphysics—new essays on the foundations of ontology. Oxford University Press, Oxford, 2009) are examined; all are shown to be faulty. In the process, constructive reasons for regarding the debate as a substantive one are provided. It is also suggested that the theories may have differing practical implications.