Deontic action logic, atomic boolean algebras and fault-tolerance

We introduce a deontic action logic and its axiomatization. This logic has some useful properties (soundness, completeness, compactness and decidability), extending the properties usually associated with such logics. Though the propositional version of the logic is quite expressive, we augment it with temporal operators, and we outline an axiomatic system for this more expressive framework. An important characteristic of this deontic action logic is that we use boolean combinators on actions, and, because of finiteness restrictions, the generated boolean algebra is atomic, which is a crucial point in proving the completeness of the axiomatic system. As our main goal is to use this logic for reasoning about fault-tolerant systems, we provide a complete example of a simple application, with an attempt at formalization of some concepts usually associated with fault-tolerance.     

Expressivity results for deontic logics of collective agency

We use a deontic logic of collective agency to study reducibility questions about collective agency and collective obligations. The logic that is at the basis of our study is a multi-modal logic in the tradition of stit (‘sees to it that’) logics of agency. Our full formal language has constants for collective and individual deontic admissibility, modalities for collective and individual agency, and modalities for collective and individual obligations. We classify its twenty-seven sublanguages in terms of their expressive power. This classification enables us to investigate reducibility relations between collective deontic admissibility, collective agency, and collective obligations, on the one hand, and individual deontic admissibility, individual agency, and individual obligations, on the other.

     

From Oughts to Goals: A Logic for Enkrasia

This paper focuses on (an interpretation of) the Enkratic principle of rationality, according to which rationality requires that if an agent sincerely and with conviction believes she ought to X, then X-ing is a goal in her plan. We analyze the logical structure of Enkrasia and its implications for deontic logic. To do so, we elaborate on the distinction between basic and derived oughts, and provide a multi-modal neighborhood logic with three characteristic operators: a non-normal operator for basic oughts, a non-normal operator for goals in plans, and a normal operator for derived oughts. We prove two completeness theorems for the resulting logic, and provide a dynamic extension of the logic by means of product updates. We illustrate how this setting informs deontic logic by considering issues related to the filtering of inconsistent oughts, the restricted validity of deontic closure, and the stability of oughts and goals under dynamics.

     

An Intuitionistic Reformulation of Mally’s Deontic Logic

In 1926, Ernst Mally proposed a number of deontic postulates. He added them as axioms to classical propositional logic. The resulting system was unsatisfactory because it had the consequence that A is the case if and only if it is obligatory that A. We present an intuitionistic reformulation of Mally’s deontic logic. We show that this system does not provide the just-mentioned objectionable theorem while most of the theorems that Mally considered acceptable are still derivable. The resulting system is unacceptable as a deontic logic, but it does make sense as a lax logic in the modern sense of the word.     

Action negation and alternative reductions for dynamic deontic logics

Dynamic deontic logics reduce normative assertions about explicit complex actions to standard dynamic logic assertions about the relation between complex actions and violation conditions. We address two general, but related problems in this field. The first is to find a formalization of the notion of ‘action negation’ that (1) has an intuitive interpretation as an action forming combinator and (2) does not impose restrictions on the use of other relevant action combinators such as sequence and iteration, and (3) has a meaningful interpretation in the normative context. The second problem we address concerns the reduction from deontic assertions to dynamic logic assertions. Our first point is that we want this reduction to obey the free-choice semantics for norms. For ought-to-be deontic logics it is generally accepted that the free-choice semantics is counter-intuitive. But for dynamic deontic logics we actually consider it a viable, if not, the better alternative. Our second concern with the reduction is that we want it to be more liberal than the ones that were proposed before in the literature. For instance, Meyer's reduction does not leave room for action whose normative status is neither permitted nor forbidden. We test the logics we define in this paper against a set of minimal logic requirements.     

Logical dynamics of some speech acts that affect obligations and preferences

In this paper, illocutionary acts of commanding will be differentiated from perlocutionary acts that affect preferences of addressees in a new dynamic logic which combines the preference upgrade introduced in DEUL (dynamic epistemic upgrade logic) by van Benthem and Liu with the deontic update introduced in ECL II (eliminative command logic II) by Yamada. The resulting logic will incorporate J. L. Austin’s distinction between illocutionary acts as acts having mere conventional effects and perlocutionary acts as acts having real effects upon attitudes and actions of agents, and help us understand why saying so can make it so in explicit performative utterances. We will also discuss how acts of commanding give rise to so-called “deontic dilemmas” and how we can accommodate most deontic dilemmas without triggering so-called “deontic explosion”.     

Development of the deontic advantage in reasoning: Reply to Cummins

In response to Cummins’s report that comments on our article (Dack & Astington, Journal of Experimental Child Psychology, 2011, Vol. 110, pp. 94–114), this article clarifies our perspective on what constitutes the deontic advantage, and notes similarities and differences between Cummins’s perspective and our own. Like Cummins, we believe that young children are capable of deontic reasoning and that methodological factors alone cannot explain this ability. However, we maintain that it is important to be precise about methodology in order to facilitate investigation of how the deontic advantage changes over developmental time, and this question is our main interest, although as yet incompletely answered. Contrary to Cummins, we do not think that existing data can speak to the issue of the potential innateness of deontic reasoning. We also disagree with Cummins’s perspective on norm versus normative proposition and with some of her comparisons between deontic and epistemic phenomena.     

Love in the Time of Consequentialism

There are several powerful motivations for neutral value‐based deontic theories such as Act Consequentialism. Traditionally, such theories have had great difficulty accounting for partiality towards one's personal relationships and projects. This paper presents a neutral value‐based theory that preserves the motivations for Act Consequentialism while vindicating some crucial intuitions about reasons to be partial. There are two central ideas. The first is that when it comes to working out what you ought to do, your friends’ interests, the needs of your family, the significance of your own projects and ideals, etc. have more weight than the interests and needs of strangers. Your friends’ interests are not (thereby) more neutrally valuable than the interests of others. So there is a difference between the value of an outcome and its deontic significance. The second familiar idea is that reasons are modifiable. Reasons of partiality are reasons the weights of which are a function of the value of the relevant outcome modified by facts about the value of caring about the outcome in question. The resulting principle has various further explanatory advantages; in particular, it accounts for project‐ and relationship‐specific permissions and requirements, both at a time and across time.     

Concrete problems in the abstract deontic selection task - and how to solve them

The abstract deontic selection task was introduced by Cheng and Holyoak with the aim of demonstrating that people possess abstract reasoning schemas for processing deontic rules about what an individual must, must not, may, or need not do. Solving this task requires people to detect possible rule violators. The average solution rate across several studies, while being substantially higher than that with abstract nondeontic tasks, did not reach the level obtained with concrete deontic tasks. A task analysis based on the deontic principles by Beller uncovers several problems with the formulation of the original task. They concern the presentation of the deontic rule as well as the instructions (focusing on rule following) and result in a specific selection behaviour. Three experiments replicate the difficulties with the original task and show that task performance increases when the formulation problems are resolved. The best performance was obtained with a task that combined a genuine violation detection instruction with a genuine permission rule. Interestingly, permissions are weak deontic rules that, if taken literally, cannot be violated in a deontic sense. Therefore, people must interpret these rules as implying a strong deontic constraint (i.e., a ban), which then constitutes the basis for solving the task. The results provide novel insights into the interpretation of deontic rules and into the role that these content-specific, but abstract, tasks can play for the study of reasoning processes.     

Understanding conditional promises and threats

Conditional promises and threats are speech acts that are used to manipulate other people's behaviour. Studies on human reasoning typically use propositional logic to analyse what people infer from such inducements. While this approach is sufficient to uncover conceptual features of inducements, it fails to explain them. To overcome this limitation, we propose a multilevel analysis integrating motivational, linguistic, deontic, behavioural, and emotional aspects. Commonalities and differences between conditional promises and threats on various levels were examined in two experiments. The first shows that both types of inducements are understood as being complementary on the linguistic level, but not reversible, due to the specific temporal order of their actions. In addition, it gives a first assessment of emotional reactions. The second experiment investigated the novel question of whether complementary promises and threats, despite semantic differences, both imply an obligation to cooperate on the deontic level. The data corroborate this hypothesis, and they support various appraisal-theoretical assumptions on the elicitation of emotions. They also reveal that content affects not only the attribution of emotions, but also the deontic interpretation.     

Motive and Right Action

Some philosophers believe that a change in motive alone is sometimes sufficient to bring about a change in the deontic status (rightness or wrongness) of an action. I refer to this position as ‘weak motivism’, and distinguish it from ‘strong’ and ‘partial motivism’. I examine a number of cases where our intuitive judgements appear to support the weak motivist’s thesis, and argue that in each case an alternative explanation can be given for why a change in motive brings about (or, in some cases, appears to bring about) a change in deontic status.     

Evidence of deontic reasoning in 3- and 4-year-old children

Deontic reasoning is reasoning about what one may, ought, or ought not do in a given set of circumstances. Virtually all of our social institutions and child-rearing practices presume the capacity to reason about deontic concepts, such as what is permitted, obligated, or prohibited. Despite this, very little is known about the development of deontic reasoning. Two experiments were conducted that contrasted children’s reasoning performance on deontic and indicative reasoning tasks (i.e., the reduced array selection version of the Wason card selection task). Like adults, children as young as 3 years of age were found to adopt a violation-detecting strategy more often when reasoning about the deontic case than when reasoning about the indicative case. These results indicate that violation detection emerges as an effective deontic reasoning very early in human development.     

Domains of deontic reasoning: Resolving the discrepancy between the cognitive and moral reasoning literatures

Deontic reasoning has been studied in two subfields of psychology: the cognitive and moral reasoning literatures. These literatures have drawn different conclusions about the nature of deontic reasoning. The consensus within the cognitive reasoning literature is that deontic reasoning is a unitary phenomenon, whereas the consensus within the moral reasoning literature is that there are different subdomains of deontic reasoning. We present evidence from a series of experiments employing the methods of both literatures suggesting that people make a systematic distinction between two types of deontic rule: social contracts and precautions. The results call into question the prevailing opinion in the cognitive reasoning literature and provide further support for both an evolutionary view of deontic reasoning and the more domain-specific perspective found in the moral reasoning literature.     

Conflict detection during moral decision-making: evidence for deontic reasoners’ utilitarian sensitivity

Moral dilemmas often force us to decide between deontological (harming others is wrong) and utilitarian (harming others can be acceptable depending on the consequences) considerations. Cognitive scientists have shown that utilitarian responders typically engage demanding deliberate thinking to override a conflicting intuitive deontological response. A key question is whether deontic responders also take utilitarian considerations into account and detect that there are conflicting responses at play. The present study addressed this issue by contrasting people's processing of moral dilemmas in which utilitarian and deontological considerations cued conflicting or non-conflicting decisions. Results showed that deontic responders were slower and less confident about their decision when solving the conflict (vs. no-conflict) dilemmas. This suggests that they are considering both deontic and utilitarian aspects of their decision and indicates that a deontic decision is more informed and less oblivious than it might appear.     

Leibniz and the Square: A Deontic Logic for the Vir Bonus

Seventeenth century philosopher Gottfried Leibniz's contributions to metaphysics, mathematics, and logic are well known. Lesser known is his ‘invention’ of deontic logic, and that his invention derives from the alethic logic of the Aristotelian square of opposition. In this paper, I show how Leibniz developed this ‘logic of duties’, which designates actions as ‘possible, necessary, impossible, and omissible’ for a ‘vir bonus’ (good person). I show that for Leibniz, deontic logic can determine whether a given action, e.g. as permitted, is therefore obligatory or prohibited (impossible). Secondly, since the deontic modes are derived from what is possible, necessary, etc., for a good person to do, and that ‘right and obligation’ are the ‘moral qualities’ of a good person, we can see how Leibniz derives deontic logic from these moral qualities. Finally, I show how Leibniz grounds a central deontic concept, namely obligation, in the human capacity for freedom.     

Moral dilemmas,disjunctive obligations,and Kant's principle that ‘ought’ implies ‘can’

In moral dilemmas, where circumstances prevent two or more equally justified prima facie ethical requirements from being fulfilled, it is often maintained that, since the agent cannot do both, conjoint obligation is overridden by Kant's principle that ought implies can, but that the agent nevertheless has a disjunctive obligation to perform one of the otherwise obligatory actions or the other. Against this commonly received view, it is demonstrated that although Kant's ought-can principle may avoid logical inconsistency, the principle is incompatible with disjunctive obligation in standard deontic logic, and that it entails paradoxically that none of the conflicting dilemma actions will in fact occur. The principle appears to provide the only plausible safeguard against deontic antinomy, but cannot be admitted because of its collision with considered moral judgments.     

Moral dilemmas and nonmonotonic logic

Conclusion From a philosophical standpoint, the work presented here is based on van Fraassen [26]. The bulk of that paper is organized around a series of arguments against the assumption, built into standard deontic logic, that moral dilemmas are impossible; and van Fraassen only briefly sketches his alternative approach. His paper ends with the conclusion that the problem of possibly irresolvable moral conflict reveals serious flaws in the philosophical and semantic foundations of orthodox deontic logic, but also suggests a rich set of new problems and methods for such logic. My goal has been to suggest that some of these methods might be found in current research on nonmonotonic reasoning, and that some of the problems may have been confronted there as well.I have shown that nonmonotonic logics provide a natural framework for reasoning about moral dilemmas, perhaps even more useful than the ordinary modal framework, and that the issues surrounding the treatment of exceptional information within these logics run parallel to some of the problems posed by conditional oughts. However, there is also another way in which deontic logic might benefit from a connection to nonmonotonic reasoning. A familiar criticism among ethicists of work in deontic logic is that it is too abstract, and too far removed from the kind of problems confronted by real agents in moral deliberation. It must be said that similar criticisms of abstraction and irrelevance are often lodged against work in nonmonotonic reasoning by more practically minded researchers in artificial intelligence; but here, at least, the criticisms are taken seriously. Nonmonotonic logic aims at a qualitative account of commonsense reasoning, which can be used to relate planning and action to defeasible goals and beliefs; and at least some of the theories developed in this area have been tested in realistic situations. By linking the subject of deontic logic to this research, it may be possible also to relate the idealized study of moral reasoning typical of the field to a more robust treatment of practical deliberation.     

Conditions for the acceptance of deontic conditionals.

Recent psychological research has investigated how people assess the probability of an indicative conditional. Most people give the conditional probability of q given p as the probability of if p then q. Asking about the probability of an indicative conditional, one is in effect asking about its acceptability. But on what basis are deontic conditionals judged to be acceptable or unacceptable? Using a decision theoretic analysis, we argue that a deontic conditional, of the form if p then must q or if p then may q, will be judged acceptable to the extent that the p & q possibility is preferred to the p & not-q possibility. Two experiments are reported in which this prediction was upheld. There was also evidence that the pragmatic suitability of permission rules is partly determined by evaluations of the not-p & q possibility. Implications of these results for theories of deontic reasoning are discussed.