Hans Rott

According to Otto Neurath, the practice of science consists in a large undertaking of setting up and maintaining systems of statements: In unified science we try ... to create a consistent system of protocol statements and nonprotocol statements . When a new statement is presented to us we compare it with the system at our disposal and check whether the new statement is in contradiction with the system or not. If the new statement is in contradiction with the system, we can discard this statement as unusable , for example, the statement: ‘In Africa lions sing only in major chords’ ; however, one can also ‘accept’ the statement and change the system accordingly so that it remains consistent if this statement is added. The statement may then be called ‘true’

Prioritized bases, i.e., weakly ordered sets of sentences, have been used for specifying an agent’s ‘basic’ or ‘explicit’ beliefs, or alternatively for compactly encoding an agent’s belief state without the claim that the elements of a base are in any sense basic. This paper focuses on the second interpretation and shows how a shifting of priorities in prioritized bases can be used for a simple, constructive and intuitive way of representing a large variety of methods for the change of belief states—methods that have usually been characterized semantically by a system-of-spheres modeling. Among the methods represented are ‘radical’, ‘conservative’ and ‘moderate’ revision, ‘revision by comparison’ in its raising and lowering variants, as well as various constructions for belief expansion and contraction. Importantly, none of these methods makes any use of numbers.

This paper presents a number of apparent anomalies in rational choice scenarios, and their translation into the logic of everyday reasoning. Three classes of examples that have been discussed in the context of probabilistic choice since the 1960s (by Debreu, Tversky and others) are analyzed in a non-probabilistic setting. It is shown how they can at the same time be regarded as logical problems that concern the drawing of defeasible inferences from a given information base. I argue that initial appearances notwithstanding, these cases should not be classed as instances of irrationality in choice or reasoning. One way of explaining away their apparent oddity is to view certain aspects of these examples as making particular options salient. The decision problems in point can then be solved by ‘picking’ these options, although they could not have been ‘chosen’ in a principled way, due to ties or incomparabilities with alternative options.

Der Band vereint aktuelle Beiträge zu den Themenschwerpunkten Fiktion, Wahrheit und Interpretation im Hinblick auf fiktionale literarische Texte. Im Einzelnen werden Fragen wie die folgenden diskutiert: In welchem Verhältnis stehen Literatur und Wahrheit? Welche Rolle spielen Intentionen für die Interpretation? Sind fiktionale Texte ausschließlich fiktional? Lässt sich die Sprechakttheorie für die Beschreibung der in fiktionalen literarischen Texten enthaltenen Sätze fruchtbar machen? Warum nehmen wir Anteil an fiktionaler Literatur, obwohl wir wissen, dass die beschriebenen Personen und Ereignisse nicht real sind? Die Beiträger nehmen diese Problemfelder aus einer interdisziplinären Warte zwischen Literaturtheorie und analytischer Philosophie in den Blick.

Dieser Beitrag vergleicht G. F. Meiers Prinzip der hermeneutischen Billigkeit mit D. Davidsons „Principle of Charity". In der Literatur wurde darauf hingewiesen, daß diese sehr allgemeinen Prinzipien wohlwollender Interpretation insofern verwandt sind, als sie Sprechern und Autoren generell eine gewisse Form von Rationalität unterstellen. Doch weisen sie auch deutlich erkennbare Unterschiede auf. Während Meiers Auslegungskunst einen naiven Bedeutungsbegriff voraussetzt, wirkt Davidsons Prinzip in erster Linie bedeutungskonstitutiv. Ich setze die beiden Prinzipien in den Rahmen einer allgemeinen, hier nur grob entworfenen Theorie der Interpretation, nach der die Interpretation von Äußerungen und Texten stets ein Rekonstruktionsunternehmen darstellt, welches die Existenz von Bedeutungen elementarer lexikalischer Einheiten und grammatikalischer Konstruktionen postuliert, die kontextuell-holistisch verstanden und kompositional verknüpft werden können

In recent years there has been a growing consensus that ordinary reasoning does not conform to the laws of classical logic, but is rather nonmonotonic in the sense that conclusions previously drawn may well be removed upon acquiring further information. Even so, rational belief formation has up to now been modelled as conforming to some fundamental principles that are classically valid. The counterexample described in this paper suggests that a number of the most cherished of these principles should not be regarded as valid for commonsense reasoning. An explanation of this puzzling failure is given, arguing that a problem in the theory of rational choice transfers to the realm of belief formation.

The classical qualitative theory of belief change due to Alchourrón, Gärdenfors and Makinson has been widely known as being characterised by two packages of postulates. While the basic package consists of six postulates and is very weak, the full package that adds two further postulates is very strong. I revisit two classic constructions of theory contraction, viz., relational possible worlds contraction and entrenchment-based contraction and argue that four intermediate levels can be distinguished that play - or ought to play - important roles within qualitative belief revision theory. Levels 3 and 4 encode two ways of interpreting the idea of imperfect discrimination of the plausibilities of possible worlds or propositions.

The paper attempts to reconcile two very different approaches to the concept of causation. In the original form, it is the opposition found in Laplace between his doctrine of constant and variable causes on the one hand and his mechanistic determinism on the other. This tension was described clearly only by Maxwell who stressed the contrast between the statistical and the dynamical method (calling the latter also the historical or strictly kinetic method). A similar dichotomy surfaces in the work of Wesley Salmon who distinguished statistical from aleatory causation. Acknowledging that we seem to have conflicting intuitions about causality and explanation, I argue that assigning probabilistic laws a fundamental role in scientific explanation does not conflict with the assumption of Laplacian determinism. This is due to the fact that in most systems of interest, we confront a complex interaction of multiple causal factors and an extreme sensitivity to small variations of initial conditions.

This paper investigates the formal relationship between two prominent approaches to the logic of belief change. The first one uses the idea of "relational partial meet contractions" as developed by Alchourrón, Gärdenfors and Makinson (Journal of Symbolic Logic 1985), the second one uses the concept of "epistemic entrenchment" as elaborated by Gärdenfors and Makinson (in Theoretical Aspects of Reasoning about Knowledge, M. Y. Vardi, Los Altos 1988). The two approaches are shown to be strictly equivalent via direct links between the underlying formal relations. The paper closes with observations about the application of epistemic entrenchment to simple and iterated revisions.

According to Otto Neurath, the practice of science consists in a large undertaking of setting up and maintaining systems of statements: In unified science we try... to create a consistent system of protocol statements and nonprotocol statements. When a new statement is presented to us we compare it with the system at our disposal and check whether the new statement is in contradiction with the system or not. If the new statement is in contradiction with the system, we can discard this statement as unusable, for example, the statement: ‘In Africa lions sing only in major chords’ ; however, one can also ‘accept’ the statement and change the system accordingly so that it remains consistent if this statement is added. The statement may then be called ‘true’.

Richard Bradley has initiated a new debate, with Brian Hill and Jake Chandler as further participants, about the implications of a number of so-called triviality results surrounding the Ramsey test for conditionals. I comment on this debate and argue that ‘Inclusion’ and ‘Preservation’, which were originally introduced as postulates for the rational revision of factual beliefs, have little to recommend them in the first place when extended to languages containing conditionals. I question the philosophical method of postulation that was applied in the new debate, and instead base my arguments on explicit representations of belief states and canonical constructions of belief state revisions.

This paper studies the idea of conservatism with respect to belief change strategies in the setting of unary, iterated belief revision functions (based on the conclusions of Rott, ‘Coherence and Conservatism in the Dynamics of Belief, Part I: Finding the Right Framework’, Erkenntnis 50, 1999, 387–412). Special attention is paid to the case of ‘basic belief change’ where neither the (weak) AGM postulates concerning conservatism with respect to beliefs nor the (stong) supplementary AGM postulates concerning dispositional coherence need to be satisfied. One‐step belief change generated by ‘basic entrenchment’ is combined with a natural conservative method of revising entrenchment relations. A logical characterization of this method is presented, and it is compared with three other methods known from the literature which I call ‘external’, ‘radical’ and ‘moderate’ belief revision. While conservative belief change turns out to be incoherent in its treatment of the recency of information, moderate belief change is more satisfactory in this respect.

In this paper I discuss the foundations of a formal theory of coherent and conservative belief change that is (a) suitable to be used as a method for constructing iterated changes of belief, (b) sensitive to the history of earlier belief changes, and (c) independent of any form of dispositional coherence. I review various ways to conceive the relationship between the beliefs actually held by an agent and her belief change strategies (that also deal with potential belief sets), show the problems they suffer from, and suggest that belief states should be represented by unary revision functions that take sequences of inputs. Three concepts of coherence implicit in current theories of belief change are distinguished: synchronic, diachronic and dispositional coherence. Diachronic coherence is essentially identified with what is known as conservatism in epistemology. The present paper elaborates on the philosophical motivation of the general framework; formal details and results are provided in a companion paper.