Online research in philosophy

A suggestion is made for representing iterated deontic modalities in stit theory, the “seeing-to-it-that” theory of agency. The formalization is such that normative sentences are represented as agentive sentences and therefore have history dependent truth conditions. In contrast to investigations in alethic modal logic, in the construction of systems of deontic logic little attention has been paid to the iteration... of the deontic modalities.

In order to avoid the paradoxes of standard deontic logic, we have to give up the semantic construction that identifies obligatory status with presence in all elements of a subset of the set of possible worlds. It is proposed that deontic logic should instead be based on a preference relation, according to the principle that whatever is better than something permitted is itself permitted. Close connections hold between the logical properties of a preference relation and those of the deontic logics that are derived from it in this way. The paradoxes of SDL can be avoided with this construction, but it is still an open question what type of preference relation is best suited to be used as a basis for deontic logic.

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.

This paper shows that the Dawson technique of modelling deontic logics into alethic modal logics to gain insight into deontic formulas is not available for modelling a normal (in the spirit of Anderson) relevance deontic modal logic into either of the normal relevance alethic modal logics R S4or R M. The technique is to construct an extension of the well known entailment matrix set M 0and show that the model of the deontic formula P (A v B). PA v PB is excluded.

Situationist deontic logic is a model of that fraction of normative discourse which refers to only one situation and one set of alternatives. As we can see from a whole series of well-known paradoxes, standard deontic logic (SDL) is seriously mistaken even at the situationist level. In this paper it is shown how a more realistic deontic logic can be based on the assumption that prescriptive predicates satisfy the property of contranegativity. A satisfactory account of situation-specific norms is a necessary prerequisite for a successful treatment of more complex normative structures.

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).

Deontic reasoning is reasoning about permission and obligation: what one may do and what one must do, respectively. Conceivably, people could reason about deontic matters using a purely formal deontic calculus. I review evidence from a range of psychological experiments suggesting that this is not the case. Instead, I argue that deontic reasoning is supported by a collection of dissociable cognitive adaptations for solving adaptive problems that likely would have confronted ancestral humans.

This paper introduces Exclusion Logic - a simple modal logic without negation or disjunction. We show that this logic has an efficient decision procedure. We describe how Exclusion Logic can be used as a deontic logic. We compare this deontic logic with Standard Deontic Logic and with more syntactically restricted logics.

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.