A structured argumentation framework for detaching conditional obligations

We present a general formal argumentation system for dealing with the detachment of conditional obligations. Given a set of facts, constraints, and conditional obligations, we answer the question whether an unconditional obligation is detachable by considering reasons for and against its detachment. For the evaluation of arguments in favor of detaching obligations we use a Dung-style argumentation-theoretical semantics. We illustrate the modularity of the general framework by considering some extensions, and we compare the framework to some related approaches from the literature.Comment: This is our submission to DEON 2016, including the technical appendi

Ethical consistency and the logic of ought

In Ethical Consistency, Bernard Williams vindicated the possibility of moral conflicts; he proposed to consistently allow for the presence of such conflicts within the logic of 'ought'. In determining the nature of moral conflict, Williams stressed its contingency. In this paper, Williams’ characterization of moral conflict is defended. However, Williams’ solution for consistently allowing for such conflicts within the logic of 'ought' is shown to be too crude. Whereas Williams rejects all applications of the agglomeration rule in the logic of 'ought', it is shown that a more sophisticated approach is needed. An alternative solution is presented in which the application of the agglomeration rule is made conditional upon the principle that "ought implies can"

Reasoning by Cases in Structured Argumentation

We extend the $ASPIC^+$ framework for structured argumentation so as to allow applications of the reasoning by cases inference scheme for defeasible arguments. Given an argument with conclusion `$A$ or $B$', an argument based on $A$ with conclusion $C$, and an argument based on $B$ with conclusion $C$, we allow the construction of an argument with conclusion $C$. We show how our framework leads to different results than other approaches in non-monotonic logic for dealing with disjunctive information, such as disjunctive default theory or approaches based on the OR-rule (which allows to derive a defeasible rule `If ($A$ or $B$) then $C$', given two defeasible rules `If $A$ then $C$' and `If $B$ then $C$'). We raise new questions regarding the subtleties of reasoning defeasibly with disjunctive information, and show that its formalization is more intricate than one would presume.Comment: Proceedings of SAC/KRR 201

Adaptive logic characterizations of input/output logic

We translate unconstrained and constrained input/output logics as introduced by Makinson and van der Torre to modal logics, using adaptive logics for the constrained case. The resulting reformulation has some additional benefits. First, we obtain a proof-theoretic (dynamic) characterization of input/output logics. Second, we demonstrate that our framework naturally gives rise to useful variants and allows to express important notions that go beyond the expressive means of input/output logics, such as violations and sanctions

Black ravens, white shoes and scientific evidence : the Ravens Paradox and/in scientific practice

1BLACK RAVENS, WHITE SHOES AND SCIENTIFIC EVIDENCE.THE RAVENS PARADOX AND/IN SCIENTIFIC PRACTICEErik Weber, Mathieu Beirlaen&Inge De BalCentre for Logic and Philosophy of ScienceGhent University (UGent)Blandijnberg 2, B-9000 Gent , BelgiumAbstractA well-known consequence of Hempel’s account of confirmation is the RavensParadox. In this paper we discuss this paradox from the viewpointof scientific practice. The main worry, when looking at this paradox from a scientific practiceperspective, is that it seems to lead to problematic methodological advice for scientists: it seems to licence ‘indoor ornithology’. We show that this problematic advice only follows from Hempel’s account if one adoptsa suboptimal viewof what counts as evidence for anhypothesis. We present and defend a more sophisticated viewof what counts as evidence, whichtakesrandom sampling–an important methodological principle in scientific practice–into account. On this sophisticated view, the problematic methodological advice connected tothe RavensParadox is avoided

Non-monotonic reasoning with normative conflicts in multi-agent deontic logic

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