We characterize Δ20-categoricity in Boolean algebras and linear orderings under some extra effectiveness conditions. We begin with a study of the relativized notion in these structures.

In many classes of structures, each computable structure has computable dimension 1 or $\omega$. Nevertheless, Goncharov showed that for each $n < \omega$, there exists a computable structure with computable dimension $n$. In this paper we show that, under one natural definition of relativized computable dimension, no computable structure has finite relativized computable dimension greater than 1.

The purpose of this study is to explore with more rigor and detail the role of social norms in tax compliance. This study draws on Cialdini and Trost’s (The Handbook of Social Psychology: Oxford University Press, Boston, MA, 1998) taxonomy of social norms to investigate with more specificity this potentially decisive (Alm and McKee, Managerial and Decision Economics, 19:259–275, 1998) influence on tax compliance. We test our research hypotheses regarding the direct and indirect influences of social norms using a hypothetical (...) compliance scenario with 174 experienced taxpayers as participants. Factor analysis of the social norm questions successfully identified four distinct social norm constructs, in line with Cialdini and Trost (1998). Results of the path analysis show that individuals’ standards for behavior/ethical beliefs (personal norms) as well as the expectations of close others (subjective norms) directly influence tax compliance decisions, whereas general societal expectations (injunctive norms) and other individuals’ actual behavior (descriptive norms) have an indirect influence. This shows that social norms have important direct as well as indirect influences on tax compliance behavior. We also investigate a number of attitudinal variables that may be related to social norms and taxpayer compliance. The results of this study further clarify the important role that social norms have with regard to taxpayers’ compliance behavior. (shrink)

We study the complexity of the isomorphism relation on classes of computable structures. We use the notion of FF-reducibility introduced in [9] to show completeness of the isomorphism relation on many familiar classes in the context of all ${\mathrm{\Sigma }}_{1}^{1}$ equivalence relations on hyperarithmetical subsets of ω.

The original Dutch version of this book, whose translator is Herbert D. Morton, was a 1979 doctoral dissertation in philosophy at the Free University of Amsterdam. J. van der Hoeven of the Free University and G. Nuchelmans of the University of Leiden were supervisors of the dissertation. Undoubtedly this monograph was an excellent dissertation which showed its author to be capable of making significant contributions to the history and philosophy of logic. In his commentary on a fragment of John Stuart (...) Mill's logical theory, de Jong shows that he is capable of selecting relevant material from several medieval and early modern logicians and of using interpretations and criticisms of contemporaries. For instance, the concluding chapter, "Appraisal," compares Mill and Kripke on naming. The historical and contemporary sources are relevant for establishing significant theses about Mill's logical theory. He exhibits a talent for portraying logical and semantical theories on charts and diagrams. These several charts and diagrams are some of the most valuable parts of the book. His numerous critical comments on the many views and doctrines summarized indicate an awareness of crucial philosophical problems. Unfortunately, features which fulfill the dissertation function of showing the author capable of making significant contributions may hinder readers from appreciating this book itself as being a significant contribution to the history or philosophy of logic or to the interpretation of John Stuart Mill. The display of so many themes from so many historical figures becomes confusing. The need in a dissertation to show critical awareness leads, in my judgment, to frequent use of the correct but superficial criticism that a writer used concepts in an unclear way. We are led to fear this type of unsympathetic criticism when we read on the first page of the introduction the phrase: "Mill's outrageously sloppy manner of formulating." We should hope that de Jong exploits his dissertation to develop more narrowly focused and more penetrating analyses in papers and in monographs whose significance can be more readily appreciated. (shrink)

For a computable structure A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal{A}}$$\end{document}, there may not be a computable infinitary Scott sentence. When there is a computable infinitary Scott sentence φ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\varphi}$$\end{document}, then the complexity of the index set I\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${I}$$\end{document} is bounded by that of φ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\varphi}$$\end{document}. There are results giving “optimal” Scott sentences for (...) structures of various familiar kinds. These results have been driven by the thesis that the complexity of the index set should match that of an optimal Scott sentence. In this note, it is shown that the thesis does not always hold. For a certain subgroup of Q\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathbb{Q}}$$\end{document}, there is no computable d-Σ2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Sigma_2}$$\end{document} Scott sentence, even though the index set is d-Σ20\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Sigma^0_2}$$\end{document}. (shrink)

This article provides an introduction to the articles in this theme issue. This collection examines epistemological, ontological, moral and political questions in medicine in light of the philosophical ideas of Charles Taylor. A synthesis of Taylor's relevant work is presented. Taylor has argued for a conception of the human sciences that regards human life as meaningful–deriving meaning from surrounding horizons of significance. An overview of the interdisciplinary articles in this issue is presented. This collection advances our thinking in the (...) philosophy of medicine as well as the philosophy of Charles Taylor. (shrink)