Logic Games are Complete for Game Logics

Game logics describe general games through powers of players for forcing outcomes. In particular, they encode an algebra of sequential game operations such as choice, dual and composition. Logic games are special games for specific purposes such as proof or semantical evaluation for first-order or modal languages. We show that the general algebra of game operations coincides with that over just logical evaluation games, whence the latter are quite general after all. The main tool in proving this is a representation of arbitrary games as modal or first-order evaluation games. We probe how far our analysis extends to product operations on games. We also discuss some more general consequences of this new perspective for standard logic.     

Self‐perceived competence,learning conceptions and preferred learning situations in the domain of communication

Background: An important purpose of education in the field of social work is the development of social‐communicative competence and students' individual learning theories (ILTs) concerning this domain. Aims: Our first aim was to develop diagnostic instruments for ILT assessment and to understand the relationships between ILT variables. Our second purpose was to study the differences in ILT variables between students of three study years. Samples: A total of 396 full‐time social work students participated in this study: 176 first‐year, 147 second‐year and 73 fourth‐year students (92% women and 8% men). Method: Based on a theoretical framework, three questionnaires have been constructed, covering three ILT variables: self‐perceived competence, learning conceptions and preferred learning situations. For scale construction, principal component analyses and reliability analyses were conducted. ANOVAs and post hoc comparisons of means were used to investigate cross‐sectional differences regarding ILT variables. Pearson correlations and regression analyses were performed to gain more insight into the relationships between ILT variables. Results: Five aspects of self‐perceived competence, four learning conceptions and five preferred learning situations were found. Learning conceptions and self‐perceived competencies were found to be predictors of students' preferred learning situations. Many differences were found between the three groups of students, especially between the first‐year students and the others. Conclusions: When studying the acquisition of social‐communicative competence, it is important to take students' individual learning theories into account. Increased insight into the role ILTs play can be of help in improving social work education.     

Orientational Effects and Component Processes in Symmetry Detection

In previous research on symmetry detection, factors contributing to orientational effects (axis and virtual lines connecting symmetrically positioned dots) and component processes (axis selection and pointwise evaluation) have always been confounded. The reason is the restriction to bilateral symmetry (BS), with pointwise correspondences being orthogonal to the axis of symmetry. In our experiments, subjects had to discriminate random dot patterns from symmetries defined by combining 12 axis orientations (every 15°) with seven reflection angles (0°, yielding BS, and three clockwise and counterclockwise 15° steps, yielding skewed symmetry, SS). In Experiment 1, with completely randomized trial order, a significant interaction between axis and skewing angle was obtained, indicating that classically observed orientational effects are restricted to BS and that the orientation of the pointwise correspondences is important. These basic findings were replicated in three subsequent experiments, which differed in that they used blocks containing patterns with the same axis (Experiment 2), virtual lines orientation (Experiment 3), or their combination (Experiment 4). Based on a comparison between the results obtained by these manipulations, we suggest a possible reason for the failure of preattentive symmetry detection in the case of dot patterns with SS.     

Inconsistencies in extensive games

In certain finite extensive games with perfect information, Cristina Bicchieri (1989) derives a logical contradiction from the assumptions that players are rational and that they have common knowledge of the theory of the game. She argues that this may account for play outside the Nash equilibrium. She also claims that no inconsistency arises if the players have the minimal beliefs necessary to perform backward induction. We here show that another contradiction can be derived even with minimal beliefs, so there is no paradox of common knowledge specifically. These inconsistencies do not make play outside Nash equilibrium plausible, but rather indicate that the epistemic specification must incorporate a system for belief revision. Whether rationality is common knowledge is not the issue.     

Money Pumps,Incompleteness, and Indeterminacy

In an alleged counter‐example to the completeness of rational preferences, a career as a clarinettist is compared with a career in law. It seems reasonable to neither want to judge that the law career is at least as preferred as the clarinet career nor want to judge that the clarinet career is at least as preferred as the law career. The two standard interpretations of examples of this kind are, first, that the examples show that preferences are rationally permitted to be incomplete and, second, that the examples show that preferences are rationally permitted to be indeterminate. In this paper, I shall argue that the difference between these interpretations is crucial for the money‐pump argument for transitivity, which is the standard argument that rational preferences are transitive. I shall argue that the money‐pump argument for transitivity fails if preferences are rationally permitted to be incomplete but that it works if preferences are rationally permitted to be indeterminate and rationally required to be complete.     

Profiting from poverty

We consider whether and under what conditions it is morally illicit to profit from poverty. We argue that when profit counterfactually depends on poverty, the agent making the profit is morally obliged to relinquish it. Finally, we argue that the people to whom the profit should be redirected are those on whom it counterfactually depends.