Online research in philosophy

Some requirements concerning deontic logic are formulated and discussed. Stress is laid on the need to distinguish between theories and deductive systems. It is argued that deontic theories need not be closed under the rule of detachment. Two deontic calculi, called DSC1, DSC2, are presented and talked over.

Three (apparent ) deontic antinomies are discussed: the paradoxes of the watchman and the praiser, as weIl as deontic dilemmas. A paraconsistent deontic logic, Ad, is put forward whose underlying 1st-order calculus is an infinite-valued tensorial logic. Several arguments are offered bearing out be existence of deontic contradictions, while two ways of dealing with conditional obligation paradoxes within the framework of Ad are canvassed. While the aggregation rule and the ought-implies-can principle are upheld, sundry schemata are shown not to obtain which involve iterated deontic operators (most conspicuously: that whatever ought to be obligatory is obligatory; and that it is obligatory that whatever ought to be the case should in fact be the case).

The chief aim of the paper is to extend the calculusDSC 1 (see [4]) in such a way as to satisfy all the requirements listed in [4] as well as a further stipulation — called the principle of uninvolvement — to the effect that neither deontic compatibility nor deontic incompatibility of codes (see [2]) should be presupposed in deontic logic.

We report two new phenomena of deontic reasoning: (1) For conditionals with deontic content such as, "If the nurse cleaned up the blood then she must have worn rubber gloves", reasoners make more modus tollens inferences (from "she did not wear rubber gloves" to "she did not clean up the blood") compared to conditionals with epistemic content. (2) For conditionals in the subjunctive mood with deontic content, such as, "If the nurse had cleaned up the blood then she must have had to wear rubber gloves", reasoners make the same frequency of all inferences as they do for conditionals in the indicative mood with deontic content. In this regard, subjunctive deontics are different from subjunctive epistemic conditionals: reasoners interpret subjunctive epistemic conditionals as counterfactual and they make more negative inferences such as modus tollens from them. The experiments show these two phenomena occur for deontic conditionals that contain the modal auxiliary "must" and ones that do not. We discuss the results in terms of the mental representations of deontic conditionals and of counterfactual conditionals.

Introduction -- Instrumental rationality -- Social order -- Deontic constraint -- Intentional states -- Preference noncognitivism -- A naturalistic perspective -- Transcendental necessity -- Weakness of will -- Normative ethics.

This paper compares two ways of formalising defeasible deontic reasoning, both based on the view that the issues of conflicting obligations and moral dilemmas should be dealt with from the perspective of nonmonotonic reasoning. The first way is developing a special nonmonotonic logic for deontic statements. This method turns out to have some limitations, for which reason another approach is recommended, viz. combining an already existing nonmonotonic logic with a deontic logic. As an example of this method the language of Reiter's default logic is extended to include modal expressions, after which the argumentation framework in default logic of [20, 22] is used to give a plausible logical analysis of moral dilemmas and prima facie obligations.

The purpose of this paper is to e»tahlish some connections between precedent-based reasoning as it is studied in the field of Artificial Intelligence and Law, particularly in the work of Ashley, and two other fields: deontic logic and nonmonotonic logic. First, a deontic logic is described that allows lor sensible reasoning in the presence of conflicting norms. Second, a simplified version of Ashley's account of precedent-based reasoning is reformulated within the framework of this deontic logic. Finally, some ideas from the theory of nonmonotonic inheritance are employed to show how Ashley's account might be elaborated to allow for a richer representation of the process of argumentation.

There seems to be no clear consensus in the existing literature about the role of deontic logic in legal knowledge representation — in large part, we argue, because of an apparent misunderstanding of what deontic logic is, and a misplaced preoccupation with the surface formulation of legislative texts. Our aim in this paper is to indicate, first, which aspects of legal reasoning are addressed by deontic logic, and then to sketch out the beginnings of a methodology for its use in the analysis and representation of law.The essential point for which we argue is that deontic logic — in some form or other —needs to be taken seriously whenever it is necessary to make explicit, and then reason about, the distinction between what ought to be the case and what is the case, or as we also say, between the ideal and the actual. We take the library regulations at Imperial College as the main illustration, and small examples from genuinely legal domains to introduce specific points. In conclusion, we touch on the role of deontic logic in the development of the theory of normative positions.

Power has been studied in various guises in both the social cognition and the reasoning literatures. In this paper, three experiments are reported in which this factor was investigated in the domain of deontic thinking. Power of source of deontic statements was varied within several scenarios, and participants judged the degree to which they thought an injunction would be carried out. In the first experiment, permission statements were used, and it was found that, as predicted, power was positively related to degree of endorsement of deontic conclusions across scenarios. In the second experiment, these findings were generalised across three further deontic domains (threat, warning, and promise) and two different syntactic forms (conjunctive and disjunctive). In the third experiment, the hypothesis that power effects were mediated by subjective judgements of conditional probability was investigated and confirmed. It is argued that these results favour theories that give a general role to probabilistic factors, rather than those based on domain-specific schemas.

Deontic reasoning is thinking about whether actions are forbidden or allowed, obligatory or not obligatory. It is proposed that social norms, imposing constraints on individual actions, constitute the fundamental concept for the system of these four deontic modalities, and that people reason from such norms flexibly according to deontic core principles. Two experiments are presented, one on deontic conditional reasoning, the other on “pure” deontic reasoning. Both experiments demonstrate people's high deontic competence and confirm the proposed representational and inferential principles. Experiment 1 additionally shows small effects of the conditional formulations. These findings support the dual source approach (Beller & Spada, 2003) that distinguishes between domain-specific and domain-general inferences. Implications for other theories of deontic reasoning are discussed.