TY - JOUR T1 - Deontic Reasoning on the Basis of Consistency Considerations Y1 - Submitted A1 - Straßer, Christian A1 - Meheus, Joke A1 - Aleks Knoks AB -

Deonticconflictsposeanimportantchallengetodeonticlogicians. The standard account —standard deontic logic, SDL— is not apt for addressing this challenge since it trivializes con flicts. Two main stratagems for gaining conflict-tolerance have been proposed: to weaken SDL in various ways, and to contextualize the reign of SDL to consistent subsets of the premise set. The latter began with the work of van Fraassen and has been further developed by Horty. In this paper we characterize this second approach in general terms. We also study three basic ways to contextualize SDL and supplement each of these with a dynamic proof theory in the framework of adaptive logics.

ER - TY - JOUR T1 - Non-Adjunctive Deontic Logics That Validate Aggregation as Much as Possible JF - Journal of Applied Logic Y1 - In Press A1 - Meheus, Joke A1 - Beirlaen, Mathieu A1 - Van De Putte, Frederik A1 - Straßer, Christian ER - TY - JOUR T1 - Adaptive Logic Characterizations of Input/output Logic JF - Studia Logica Y1 - 2016 A1 - Straßer, Christian A1 - Beirlaen, Mathieu A1 - Van De Putte, Frederik AB -

We translate the unconstrained and constrained input/output-logics from [17, 18] to reflexive modal logics, using adaptive logics for the constrained case. The resulting reformulation has various advantages. First, we obtain a proof-theoretic (dynamic) characterization of input/output logics. Second, we demonstrate that our modal framework gives naturally rise to useful variants. Finally, the modal logics display a gain in expressive power over their original counterparts in the input/output framework.

VL - 104 SP - 869-916 CP - 5 ER - TY - JOUR T1 - Adaptive strategies and finite-conditional premise sets JF - Journal of Logic and Computation Y1 - 2016 A1 - Straßer, Christian A1 - Van De Putte, Frederik VL - 26 SP - 1517-1539 UR - + http://dx.doi.org/10.1093/logcom/exu044 ER - TY - JOUR T1 - Which Style of Reasoning to Choose in the Face of Conflicting Information? JF - Journal of Logic and Computation Y1 - 2016 A1 - Meheus, Joke A1 - Straßer, Christian A1 - Verdée, Peter AB -

In the context of non-monotonic reasoning different kinds of consequence relations are defined for reasoning from (possibly) inconsistent information. Examples are consequence relations that are characterized in terms of maximal consistent subsets of the premise set. The strong consequences are those formulas that follow by Classical Logic from every maximal consistent subset. The weak consequences follow from some maximal consistent subset. The free consequences follow from the set of formulas that belong to every maximal consistent subset. In this paper the question is discussed which of these consequence relations should be applied in which reasoning context. First the concerns that are expressed in the literature with respect to the usefulness of the weak consequences are addressed. Then it is argued that making weak inferences is sensible for some application contexts, provided one has a (dynamic) proof theory for the corresponding consequence relation. Such a dynamic proof theory is what adaptive logics offer. Finally, all this is illustrated by means of a very simple adaptive logic reconstruction of the free, strong, and weak consequences

VL - 26 SP - 361--380 ER - TY - Generic T1 - Withstanding Tensions: Scientific Disagreement and Epistemic Tolerance Y1 - 2015 A1 - Straßer, Christian A1 - Šešelja, Dunja A1 - Wieland, Jan Willem ED - Ippoliti, Emiliano AB -

Many philosophers of science consider scientific disagreementto be a major promoter of scientific progress. However, we lack an ac-count of the epistemically and heuristically appropriate response scien-tists should have towards opposing positions in peer disagreements. Eventhough some scientific pluralists have advocated a notion of tolerance,the implications of this notion for one’s epistemic stance and, more gen-erally, for the scientific practice have been insuficiently explicated in theliterature. In this paper we explicate a characteristic tension in whichdisagreeing scientists are situated and on this basis we propose a notionof epistemic tolerance.

JA - Heuristic Reasoning T3 - Studies in Applied Philosophy, Epistemology and Rational Ethics PB - Springer VL - 16 SP - 113–146 ER - TY - JOUR T1 - Adaptive logics: a parametric approach JF - Logic Journal of the IGPL Y1 - 2014 A1 - Van De Putte, Frederik A1 - Straßer, Christian VL - 22 SP - 905-932 UR - + http://dx.doi.org/10.1093/jigpal/jzu017 ER - TY - Generic T1 - Dynamic Derivations for Sequent-Based Deductive Argumentation T2 - COMMA 2014 Y1 - 2014 A1 - Straßer, Christian A1 - Arieli, Ofer ED - Parsons, Simon ED - Oren, Nir ED - Reed, Chris ED - Cerutti, Federico AB -

We introduce a general approach for representing and reasoning with argumentation-based systems. In our framework arguments are represented by Gentzen-style sequents, attacks (conflicts) between arguments are represented by sequent elimination rules, and deductions are made by dynamic proof systems. This framework accommodates different languages and logics in which arguments may be represented, supports a variety of attack relations, and tolerates dynamic changes in the argumentation setting by revising derivations of assertions in light of new information.

JA - COMMA 2014 VL - Computational Models of Argument SP - 89–100 ER - TY - JOUR T1 - Epistemic Justification in the Context of Pursuit: A Coherentist Approach JF - Synthese Y1 - 2014 A1 - Straßer, Christian A1 - Šešelja, Dunja AB -

The aim of this paper is to offer an account of epistemic justification suitable for the context of theory pursuit, that is, for the context in which new scientific ideas, possibly incompatible with the already established theories, emerge and are pursued by scientists. We will frame our account paradigmatically on the basis of one of the influential systems of epistemic justification: Laurence Bonjour’s coherence theory of justification. The idea underlying our approach is to develop a set of criteria which indicate that the pursued system is promising of contributing to the epistemic goal of robustness of scientific knowledge and of developing into a candidate for acceptance. In order to realize this we will (a) adjust the scope of Bonjour’s standards—consistency, inferential density, and explanatory power, and (b) complement them by the requirement of a programmatic character. In this way we allow for the evaluation of the “potential coherence” of the given epistemic system.

VL - 191 SP - 3111-3141 ER - TY - JOUR T1 - Heuristic Reevaluation of the Bacterial Hypothesis of Peptic Ulcer Disease in the 1950s JF - Acta Biotheoretica Y1 - 2014 A1 - Šešelja, Dunja A1 - Straßer, Christian AB -

Throughout the first half of the twentieth century the research on peptic ulcer disease (PUD) focused on two rivaling hypothesis: the “acidity” and the “bacterial” one. The latter was dismissed during the 1950s only to be revived with Warren’s and Marshall’s discovery of Helicobacter pylori in the 1980s. In this paper we investigate why the bacterial hypothesis was abandoned in the 1950s, and whether there were good epistemic reasons for its dismissal. Of special interest for our research question is Palmer’s 1954 large-scale study, which challenged the bacterial hypothesis with serious counter-evidence, and which by many scholars is considered as the shifting point in the research on PUD. However, we show that: 1. The perceived refutatory impact of Palmer’s study was disproportionate to its methodological rigor. This undermines its perceived status as a crucial experiment against the bacterial hypothesis. 2. In view of this and other considerations we argue that the bacterial hypothesis was worthy of pursuit in the 1950s.

VL - 62 SP - 429–454 ER - TY - JOUR T1 - Sequent-Based Argumentation for Normative Reasoning JF - Deontic Logic and Normative Systems: Lecture Notes in Computer Science Y1 - 2014 A1 - Straßer, Christian A1 - Arieli, Ofer AB -

In this paper we present an argumentative approach to normative reasoning. Special attention is paid to normative conflicts, contrary-to-duty and specificity cases. These are modeled by means of argumentative attacks. For this, we adopt a recently proposed frame- work for logical argumentation in which arguments are generated by a sequent calculus of a given base logic (Arieli, CLIMA’2013, pp.69–85), and use an intuitionistic variant of stan- dard deontic logic as our base logic. Argumentative attacks are realized by elimination rules that allow to discharge specific sequents. We demonstrate our system by means of various well-known benchmark examples.

VL - 8554 SP - 224–240 ER - TY - JOUR T1 - Abstract argumentation and explanation applied to scientific debates JF - Synthese Y1 - 2013 A1 - Šešelja, Dunja A1 - Straßer, Christian AB -

Abstract argumentation has been shown to be a powerful tool within many fields such as artificial intelligence, logic and legal reasoning. In this paper we enhance Dung's well-known abstract argumentation framework with explanatory capabilities. We show that an explanatory argumentation framework (EAF) obtained in this way is a useful tool for the modeling of scientific debates. On the one hand, EAFs allow for the representation of explanatory and justificatory arguments constituting rivaling scientific views. On the other hand, different procedures for selecting arguments, corresponding to different methodological and epistemic requirements of theory evaluation, can be formulated in view of our framework.

VL - 190 SP - 2195–2217 ER - TY - JOUR T1 - Concerning Peter Vickers' Recent Treatment of 'Paraconsistencitis' JF - International Studies in the Philosophy of Science Y1 - 2013 A1 - Šešelja, Dunja A1 - Straßer, Christian VL - 28 SP - 325–340 ER - TY - JOUR T1 - An Inconsistency-Adaptive Deontic Logic for Normative Conflicts JF - Journal of Philosophical Logic Y1 - 2013 A1 - Beirlaen, Mathieu A1 - Straßer, Christian A1 - Meheus, Joke AB -

We present the inconsistency-adaptive deontic logic \sys{DP}$^r$, a nonmonotonic logic for dealing with conflicts between normative statements. On the one hand, this logic does not lead to explosion in view of normative conflicts. On the other hand, \sys{DP}$^r$ still verifies all intuitively reliable inferences valid in Standard Deontic Logic (\sys{SDL}). \sys{DP}$^r$ interprets a given premise set ‘as normally as possible’ with respect to \sys{SDL}. Whereas some \sys{SDL}-rules are verified unconditionally by \sys{DP}$^r$, others are verified conditionally. The latter are applicable unless they rely on formulas that turn out to behave inconsistently in view of the premises. This dynamic process is mirrored by the proof theory of \sys{DP}$^r$

VL - 42 SP - 285–315 ER - TY - JOUR T1 - Kuhn and the question of pursuit worthiness JF - Topoi - An International review of philosophy Y1 - 2013 A1 - Šešelja, Dunja A1 - Straßer, Christian AB -

The aim of this paper is, on the one hand, to critically investigate Kuhn's stance on the assessment of the pursuit worthiness of scientific theories, and, on the other hand, to show the actuality of some of Kuhn's points on this issue, in view of their critical analysis. To this end we show that Kuhn presents certain tools, which may help scientists to overcome communication breakdowns when engaging in the process of rational deliberation regarding the question whether a theory is worthy of further pursuit. These tools are persuasion, translation and interpretation. However, we argue that the perspective of epistemic semantic monism present in Kuhn's work obstructs the full applicability of these tools. We show that dropping this perspective makes the notions of persuasion and interpretation more fruitful, and moreover, allows for a pluralism of scientific theories and practices that complements the pluralism based on disagreement among scientists, emphasized by Kuhn.

VL - 32 SP - 9–19 ER - TY - JOUR T1 - Non-monotonic reasoning with normative conflicts in multi-agent deontic logic JF - Journal of Logic and Computation Y1 - 2013 A1 - Beirlaen, Mathieu A1 - Straßer, Christian AB -

We present two multi-agent deontic logics that consistently accommodate various types of normative conflicts. Its language features modal operators for obligation and permission, and for the realization of individual and collective actions. The logic is non-classical since it makes use of a paraconsistent and paracomplete negation connective. Moreover, it is non-monotonic due to its definition within the adaptive logics framework for defeasible reasoning. The logic is equipped with a defeasible proof theory and semantics.

VL - 24 SP - 1179–1207 ER - TY - JOUR T1 - Preferential Semantics using Non-smooth Preference Relations JF - Journal of Philosophical Logic Y1 - 2013 A1 - Van De Putte, Frederik A1 - Straßer, Christian AB -

This paper studies the properties of eight semantic consequence relations defined from a Tarski-logic L and a preference relation &\#8826;. They are equivalent to Shoham’s so-called preferential entailment for smooth model structures, but avoid certain problems of the latter in non-smooth configurations. Each of the logics can be characterized in terms of what we call multi-selection semantics. After discussing this type of semantics, we focus on some concrete proposals from the literature, checking a number of meta-theoretic properties and elaborating on their intuitive motivation. As it turns out, many of their meta-properties only hold in case &\#8826; is transitive. To tackle this problem, we propose slight modifications of each of the systems, showing the resulting logics to behave better at the intuitive level and in metatheoretic terms, for arbitrary &\#8826;.

VL - 43 SP - 903–942 ER - TY - JOUR T1 - Reactive standard deontic logic JF - Journal of Logic and Computation Y1 - 2013 A1 - Gabbay, Dov M. A1 - Straßer, Christian AB -

We introduce a reactive variant of SDL (standard deontic logic): SDLR1 (reactive standard deontic logic). Given a Kripkean view on the semantics of SDL in terms of directed graphs where arrows → represent the accessibility relation between worlds, reactive models add two elements: arrows → are labelled as ‘active’ or ‘inactive’, and double arrows &8608; connect arrows, e.g. (x1 → x2) &\#8608; (x3 → x4). The idea is that passing through x1 → x2 activates a switch represented by &8608; that inverts the label of x3 → x4 and hence activates respectively deactivates this arrow. This allows to introduce two modalities: &\#9633; is the usual KD-modality of SDL and operates on the Kripkean graph where all labels and double arrows are ignored, while &\#8709; takes them into account. We demonstrate that RSDL1 allows for an intuitive interpretation of ‘ought’. The logic can handle contrary-to-duty cases such as several instantiations of the Chisholm set in a paradox-free way by means of using double arrows and annotations to block and give access to ideal worlds.

VL - 25 SP - 117–157 ER - TY - JOUR T1 - Three formats of prioritized adaptive logics: a comparative study JF - Logic journal of the IGPL Y1 - 2013 A1 - Van De Putte, Frederik A1 - Straßer, Christian AB -

A broad range of defeasible reasoning forms has been explicated by prioritized adaptive logics. However, the relative lack in meta-theory of many of these logics stands in sharp contrast to the frequency of their application. This article presents the first comparative study of a large group of prioritized adaptive logics. Three formats of such logics are discussed: superpositions of adaptive logics, hierarchic adaptive logics from F. Van De Putte (2011, Log. J. IGPL, doi:10.1093/jigpal/jzr025) and lexicographic adaptive logics from F. Van De Putte and C. Stra&\#223;er (2012, Log. Anal., forthcoming). We restrict the scope to logics that use the strategy Minimal Abnormality. It is shown that the semantic characterizations of these systems are equivalent and that they are all sound with respect to either of these characterizations. Furthermore, sufficient conditions for the completeness and equivalence of the consequence relations of the three formats are established. Some attractive properties, including Fixed Point and the Deduction Theorem, are shown to hold whenever these conditions are obeyed.

VL - 21 SP - 127–159 ER - TY - JOUR T1 - Two adaptive logics of norm-propositions JF - JOURNAL OF APPLIED LOGIC Y1 - 2013 A1 - Beirlaen, Mathieu A1 - Straßer, Christian AB -

We present two defeasible logics of norm-propositions (statements about norms) that (i) consistently allow for the possibility of normative gaps and normative conflicts, and (ii) map each premise set to a sufficiently rich consequence set. In order to meet (i), we define the logic LNP, a conflict- and gap-tolerant logic of norm-propositions capable of formalizing both normative conflicts and normative gaps within the object language. Next, we strengthen LNP within the adaptive logic framework for non-monotonic reasoning in order to meet (ii). This results in the adaptive logics LNPrLNPr and LNPmLNPm, which interpret a given set of premises in such a way that normative conflicts and normative gaps are avoided ‘whenever possible’. LNPrLNPr and LNPmLNPm are equipped with a preferential semantics and a dynamic proof theory.

VL - 11 SP - 147–168 ER - TY - JOUR T1 - Adaptively applying modus ponens in conditional logics of normality JF - Journal of applied non-classical logics Y1 - 2012 A1 - Straßer, Christian AB -

This paper presents an adaptive logic enhancement of conditional logics of normality that allows for defeasible applications of Modus Ponens to conditionals. In addition to the possibilities these logics already offer in terms of reasoning about conditionals, this way they are enriched by the ability to perform default inferencing itself. The idea is to apply Modus Ponens defeasibly to a conditional A&\#8605;B and a fact A on the condition that it is “safe” to do so concerning the factual and conditional knowledge at hand. It is for instance not safe if the given information describes exceptional circumstances: although birds usually fly, penguins are exceptional to this rule. The two adaptive standard strategies are shown to correspond to different intuitions, a skeptical and a credulous reasoning type, which manifest themselves in the handling of so-called floating conclusions.

VL - 22 SP - 125–148 ER - TY - JOUR T1 - Extending the standard format of adaptive logics to the prioritized case JF - Logique et Analyse Y1 - 2012 A1 - Van De Putte, Frederik A1 - Straßer, Christian AB -

This paper introduces a new format for reasoning with prioritized stan- dards of normality. It is applicable in a broad variety of contexts, e.g. dealing with (possibly conflicting) prioritized belief bases or combining different reasoning methods in a prioritized way. The format is a gener- alization of the standard format of adaptive logics (see [4]). Every logic that is formulated within it has a straightforward semantics in the style of Shoham’s selection semantics (see [22]) and a dynamic proof theory. Fur- thermore, it can count on a rich meta-theory that inherits the attractive features of the standard format, such as soundness and completeness, re- flexivity, idempotence, cautious monotonicity, and many other properties.

VL - 55 SP - 601–641 ER - TY - Generic T1 - An Andersonian deontic logic with contextualized sanctions T2 - 11th International Conference on Deontic Logic in Computer Science, DEON2012 Y1 - 2012 A1 - Straßer, Christian A1 - Beirlaen, Mathieu ED - Agotnes, Thomas ED - Broersen, Jan ED - Elgesem, Dag AB -

We present a refinement of Anderson's reduction of deontic logic to modal logic with only alethic modalities. The refined proposal contextualizes the Andersonian sanction constant s by replacing it with a unary sanction operator S that is dependent on the concrete normative requirement that is violated. A formula S B is then for instance interpreted as ldquo B causes a sanctionrdquo or as ldquo B provides a reason for (the applicability of) a sanctionrdquo. Due to its modified sanction operator, the resulting logic DSL invalidates some instances of the inheritance principle. This gives rise to new interesting features. For instance, DSL consistently allows for the presence of conflicting obligations. Moreover, it provides novel insights in various central `paradoxes' in deontic logic such as the Ross paradox, the paradox of the good Samaritan, and Forrester's `gentle murderer' paradox.

JA - 11th International Conference on Deontic Logic in Computer Science, DEON2012 PB - Springer SP - 151-169 SN - 9783642315695 ER - TY - JOUR T1 - Proof Theories for Superpositions of Adaptive Logics JF - Logique et Analyse Y1 - 2012 A1 - Straßer, Christian A1 - Van De Putte, Frederik AB -

The standard format for adaptive logics offers a generic and unifying formal framework for defeasible reasoning forms. One of its main distinguishing features is a dynamic proof theory by means of which it is able to explicate actual reasoning. In many applications it has proven very useful to superpose sequences of adaptive logics, such that each logic treats the consequence set of its predecessor as premise set. Although attempts have been made to define dynamic proof theories for some of the resulting logics, no generic proof theory is available yet. Moreover, the existing proof theories for concrete superpositions are suboptimal in various respects: the derivability relations characterized by these proposals are often not adequate with respect to the consequence relation of the superposed adaptive logics and in some cases they even trivialize premise sets. An adequate and generic proof theory is needed in order to meet the requirement of explicating defeasible reasoning in terms of superpositions of adaptive logics. This paper presents two generic proof theories for superpositions of adaptive logics in standard format. By means of simple examples, the basic ideas behind these proof theories are illustrated and it is shown how the older proposals are inadequate.

SP - 1–33 ER - TY - JOUR T1 - The rationality of scientific reasoning in the context of pursuit: drawing appropriate distinctions JF - PHILOSOPHICA Y1 - 2012 A1 - Kosolosky, Laszlo A1 - Šešelja, Dunja A1 - Straßer, Christian AB -

The aim of this paper is to disambiguate between different notions of pursuit worthiness regarding scientific inquiries. To this end we propose a unifying pattern of pursuit worthiness: “It is rational for Y to pursue X if and only if pursuing X is conducive of the set of goals Z.” By showing in which ways variables X, Y, and Z can be changed, we present different notions of pursuit and pursuit worthiness. With respect to variable X, we distinguish the pursuit of scientific theories, epistemic objects, and technological developments. With respect to variable Z, we distinguish between epistemic and practical pursuit worthiness. Finally, with respect to variable Y, we distinguish between individual and communal pursuit worthiness. By means of these distinctions we are able to explicate some of the major ambiguities underlying the concept of pursuit of pursuit worthiness, as well as to shed light on some confusions in philosophical literature that have resulted from their neglect.

VL - 86 SP - 51–82 ER - TY - JOUR T1 - Tolerating Deontic Conflicts by Adaptively Restricting Inheritance JF - Logique et Analyse Y1 - 2012 A1 - Straßer, Christian A1 - Meheus, Joke A1 - Beirlaen, Mathieu AB -

In order to deal with the possibility of deontic conflicts Lou Goble developed a group of logics DPM that are characterized by a restriction of the inheritance principle. While they approximate the deductive power of standard deontic logic, they do so only if the user adds certain statements to the premises. By adaptively strengthening the DPM logics, this paper presents logics that overcome this shortcoming. Furthermore, they are capable of modeling the dynamic and defeasible aspect of our normative reasoning by their dynamic proof theory. This way they enable us to have a better insight in the relations between obligations and thus to localize deontic conflicts.

VL - 219 SP - 477-506 ER - TY - Generic T1 - Adaptive Logic Characterizations of Defeasible Reasoning with Applications in Argumentation, Normative Reasoning and Default Reasoning Y1 - 2011 A1 - Straßer, Christian PB - Ghent University U1 -

Joke Meheus and Diderik Batens

ER - TY - Generic T1 - A paraconsistent multi-agent framework for dealing with normative conflicts T2 - 12th International Workshop on Computational Logic in Multi-Agent Systems (CLIMA XII) Y1 - 2011 A1 - Beirlaen, Mathieu A1 - Straßer, Christian ED - Leite, Joao ED - Torroni, Paolo ED - Agotnes, Thomas ED - Boella, Guido ED - van der Torre, Leon AB -

In a multi-agent deontic setting, normative conflicts can take a variety of different logical forms. In this paper, we present a very general characterization of such conflicts, including both intra- and inter-agent normative conflicts, conflicts between groups of agents, conflicts between obligations and permissions, and conflicts between contradictory norms. In order to account for the consistent possibility of this wide variety of conflict-types, we present a paraconsistent deontic logic, i.e. a logic that invalidates the classical principle of non-contradiction. Next, we strengthen this logic within the adaptive logics framework for defeasible reasoning. The resulting inconsistency-adaptive deontic logic interprets a given set of norms 'as consistently as possible'.

JA - 12th International Workshop on Computational Logic in Multi-Agent Systems (CLIMA XII) PB - Springer SP - 312-329 SN - 9783642223587 UR - http://dx.doi.org/10.1007/978-3-642-22359-4 ER - TY - JOUR T1 - Towards the proof-theoretic unification of Dung's argumentation framework: an adaptive logic approach JF - Journal of logic and computation Y1 - 2011 A1 - Straßer, Christian A1 - Šešelja, Dunja AB -

The article presents a unifying adaptive logic framework for abstract argumentation. It consists of a core system for abstract argumentation and various adaptive logics based on it. These logics represent in an accurate sense all standard extensions defined within Dung's abstract argumentation system with respect to sceptical and credulous acceptance. The models of our logics correspond exactly to specific extensions of given argument systems. Additionally, the dynamics of adaptive proofs mirror the argumentative reasoning of a rational agent. In particular, the presented logics allow for external dynamics, i.e. they are able to deal with the arrival of new arguments and are therefore apt to model open-ended argumentations by providing provisional conclusions.

VL - 21 SP - 133–156 UR - http://dx.doi.org/10.1093/logcom/exq015 ER - TY - JOUR T1 - An adaptive logic framework for conditional obligations and deontic dilemmas JF - Logic and logical philosophy Y1 - 2010 A1 - Straßer, Christian ED - Tanaka, Koji ED - Berto, Francesco ED - Mares, Edwin ED - Paoli, Francesco VL - 19 SP - 95–128 ER - TY - JOUR T1 - A deontic logic framework allowing for factual detachment JF - Journal of applied logic Y1 - 2010 A1 - Straßer, Christian AB -

Since our ethical and behavioral norms have a conditional form, it is of great importance that deontic logics give an account of deontic commitments such as “A commits you to do/bring about B”. It is commonly agreed that monadic approaches are suboptimal for this task due to several shortcomings, for instance their falling short of giving a satisfactory account of “Strengthening the Antecedent” or their difficulties in dealing with contrary-to-duty paradoxes. While dyadic logics are more promising in these respects, they have been criticized for not being able to model “detachment”: A and the commitment under A to do B implies the actual obligation to do B. “We seem to feel that detachment should be possible after all. But we cannot have things both ways, can we? This is the dilemma on commitment and detachment.” (Lennart Åqvis. Deontic logic. In D. Gabbay and F. Guenthner, editors, Handbook of Philosophical Logic, p. 199, Kluwer, Dordrecht, 2002). In this paper I answer &\#197;qvist's question with “Yes, we can”. I propose a general method to turn dyadic deontic logics in adaptive logics allowing for a defeasible factual detachment while paying special attention to specificity and contrary-to-duty cases. I show that a lot of controversy about detachment can be resolved by analysing different notions of unconditional obligations. The logical modeling of detachment is paradigmatically realized on basis of one of Lou Goble's conflict tolerant CDPM logics.

VL - 9 SP - 61–80 UR - http://dx.doi.org/10.1016/j.jal.2010.11.001 ER - TY - RPRT T1 - Towards more conflict-tolerant deontic logics by relaxing the interdefinability between obligations and permissions Y1 - 2010 A1 - Straßer, Christian A1 - Beirlaen, Mathieu AB -

While conflict-tolerant logics (CTDLs) usually allow for obligation- obligation conflicts, they fall short of tolerating obligation-permission con- flicts (OP-conflicts) of the type OA &\#8743; P&\#172; A. Moreover, for the sake of conflict-tolerance these logics usually do not validate the very intuitive principle (D), OA &\#8835; PA. We demonstrate in this paper that by relaxing the interdefinability between obligations and permission PA =df &\#172;O&\#172;A that is characteristic for most deontic logics, the logics get more conflict-tolerant since they allow for OP-conflicts. Moreover, this way they can be equipped with (D) without the need to sacrifice conflict-tolerance. In this paper we offer a generic procedure that transforms a given CTDL into a logic that tolerates OP-conflicts and validates (D).

ER - TY - JOUR T1 - A Deontic Logic Framework Allowing for Factual Detachment –- Appendix JF - Journal of Applied Logic Y1 - 2009 A1 - Straßer, Christian AB -

This Appendix contains in part A the semantic characterization of logics CDPM.2d and CDPM.2e defined in [3]. Soundness and completeness are proven. In part B the logical framework presented in [3] is generalized such that it is able to deal with nested permissible contexts.

VL - 9 SP - 61–80 ER - TY - JOUR T1 - Kuhn and coherentist epistemology JF - Studies in history and philosophy of science Y1 - 2009 A1 - Šešelja, Dunja A1 - Straßer, Christian AB -

The paper challenges a recent attempt by Jouni-Matti Kuukkanen to show that since Thomas Kuhn’s philosophical standpoint can be incorporated into coherentist epistemology, it does not necessarily lead to: (Thesis 1) an abandonment of rationality and rational interparadigm theory comparison, nor to (Thesis 2) an abandonment of convergent realism. Leaving aside the interpretation of Kuhn as a coherentist, we will show that Kuukkanen’s first thesis is not sufficiently explicated, while the second one entirely fails. With regard to Thesis 1, we argue that Kuhn’s view on inter-paradigm theory comparison allows only for (what we shall dub as) ‘the weak notion of rationality’, and that Kuukkanen’s argument is thus acceptable only in view of such a notion. With regard to Thesis 2, we show that even if we interpret Kuhn as a coherentist, his philosophical standpoint cannot be seen as compatible with convergent realism since Kuhn’s argument against it is not ‘ultimately empirical’, as Kuukkanen takes it to be.

VL - 40 SP - 322–327 UR - http://dx.doi.org/10.1016/j.shpsa.2009.06.003 ER - TY - JOUR T1 - On the Transparency of Defeasible Logics: Equivalent Premise Sets, Equivalence of Their Extensions, and Maximality of the Lower Limit JF - Logique et Analyse Y1 - 2009 A1 - Batens, Diderik A1 - Straßer, Christian A1 - Verdée, Peter AB -

For Tarski logics, there are simple criteria that enable one to conclude that two premise sets are equivalent. We shall show that the very same criteria hold for adaptive logics, which is a major advantage in comparison to other approaches to defeasible reasoning forms.
A related property of Tarski logics is that the extensions of equivalent premise sets with the same set of formulas are equivalent premise sets. This does not hold for adaptive logics. However a very similar criterion does.
We also shall show that every monotonic logic weaker than an adaptive logic is weaker than the lower limit logic of the adaptive logic or identical to it. This highlights the role of the lower limit for settling the adaptive equivalence of extensions of equivalent premise sets.

VL - 207 SP - 281–304 ER -