Avoiding deontic explosion by contextually restricting aggregation

In this paper, we present an adaptive logic for deontic conflicts, called P2.1(r), that is based on Goble's logic SDLaPe-a bimodal extension of Goble's logic P that invalidates aggregation for all prima facie obligations. The logic P2.1(r) has several advantages with respect to SDLaPe. For consistent sets of obligations it yields the same results as Standard Deontic Logic and for inconsistent sets of obligations, it validates aggregation "as much as possible". It thus leads to a richer consequence set than SDLaPe. The logic P2.1(r) avoids Goble's criticisms against other non-adjunctive systems of deontic logic. Moreover, it can handle all the 'toy examples' from the literature as well as more complex ones

How Knowledge Affects Obligations:a Study on the Logic of Knowledge-Based Obligations

A doctor generally does not have an obligation to treat a person if the doctor does not know that he/she is ill. But when the doctor knows the person is ill, the doctor ought to treat him/her. So what we ought to do depends a lot on what we know at that moment. This thesis provides a logical formalization of the concept of knowledge-based conditional obligation which paraphrases `A ought to be achieved by an agent under the condition that he/she knows B'. This notion is characterized by a sound and strongly complete axiomatization in this thesis. Furthermore, the framework is dynamified in order to show how knowledge change affects obligation change. Accordingly, those situations where agents' obligations are updated by their dynamic information can be modelled. Besides information change, norm change may also lead to new obligations. The notion of relativized conditional obligations is proposed for conceptualizing obligations induced by different normative systems. Several types of updates on normative systems are studied. They bring about new obligations or defeat original obligations in different ways. In the final chapters, this thesis jumps out of the approach of `ought-to-be' obligations and conceptualizes the notion of knowledge-based `ought-to-do' obligation based on dynamic epistemic logic. The basic idea of defining this notion is that an action ought to be done if and only if the action always improves the initial situation to a better situation. A sound and strongly complete axiom system is also established

Prelude to a Socio-logic of Imperatives

This short essay attempts to challenge some of widely held philosophical assumptions on the nature of the relationship between logic, language and reality. In Section 1 the hegemony of theoretical logic is being questioned; Section 2 proposes a hypothesis on socially mediated semantics; Section 3 addresses the problem of ontology of logical sentential moods

How Knowledge Triggers Obligation

Obligations can be affected by knowledge. Several approaches exist to formalize knowledge-based obligations, but no formalism has been developed yet to capture the dynamic interaction between knowledge and obligations. We introduce the dynamic extension of an existing logic for knowledge-based obligations here. We motivate the logic by analyzing several scenarios and by showing how it can capture in an original manner several fundamental deontic notions such as absolute, prima facie and all-things-considered obligations. Finally, in the dynamic epistemic logic tradition, we provide reduction axioms for the dynamic operator of the new logic

Evaluational adjectives

This paper demarcates a theoretically interesting class of "evaluational adjectives." This class includes predicates expressing various kinds of normative and epistemic evaluation, such as predicates of personal taste, aesthetic adjectives, moral adjectives, and epistemic adjectives, among others. Evaluational adjectives are distinguished, empirically, in exhibiting phenomena such as discourse-oriented use, felicitous embedding under the attitude verb `find', and sorites-susceptibility in the comparative form. A unified degree-based semantics is developed: What distinguishes evaluational adjectives, semantically, is that they denote context-dependent measure functions ("evaluational perspectives")—context-dependent mappings to degrees of taste, beauty, probability, etc., depending on the adjective. This perspective-sensitivity characterizing the class of evaluational adjectives cannot be assimilated to vagueness, sensitivity to an experiencer argument, or multidimensionality; and it cannot be demarcated in terms of pretheoretic notions of subjectivity, common in the literature. I propose that certain diagnostics for "subjective" expressions be analyzed instead in terms of a precisely specified kind of discourse-oriented use of context-sensitive language. I close by applying the account to `find x PRED' ascriptions

Clause-Type, Force, and Normative Judgment in the Semantics of Imperatives

I argue that imperatives express contents that are both cognitively and semantically related to, but nevertheless distinct from, modal propositions. Imperatives, on this analysis, semantically encode features of planning that are modally specified. Uttering an imperative amounts to tokening this feature in discourse, and thereby proffering it for adoption by the audience. This analysis deals smoothly with the problems afflicting Portner's Dynamic Pragmatic account and Kaufmann's Modal account. It also suggests an appealing reorientation of clause-type theorizing, in which the cognitive act of updating on a typed sentence plays a central role in theorizing about both its semantics and role in discourse

Practical Language: Its Meaning and Use

I demonstrate that a "speech act" theory of meaning for imperatives is—contra a dominant position in philosophy and linguistics—theoretically desirable. A speech act-theoretic account of the meaning of an imperative !φ is characterized, broadly, by the following claims. LINGUISTIC MEANING AS USE !φ’s meaning is a matter of the speech act an utterance of it conventionally functions to express—what a speaker conventionally uses it to do (its conventional discourse function, CDF). IMPERATIVE USE AS PRACTICAL !φ's CDF is to express a practical (non-representational) state of mind—one concerning an agent's preferences and plans, rather than her beliefs. Opposed to speech act accounts is a preponderance of views which deny that a sentence's linguistic meaning is a matter of what speech act it is used to perform, or its CDF. On such accounts, meaning is, instead, a matter of "static" properties of the sentence—e.g., how it depicts the world as being (or, more neutrally, the properties of a model-theoretic object with which the semantic value of the sentence co-varies). On one version of a static account, an imperative 'shut the window!' might, for instance, depict the world as being such that the window must be shut. Static accounts are traditionally motivated against speech act-theoretic accounts by appeal to supposedly irremediable explanatory deficiencies in the latter. Whatever a static account loses in saying (prima facie counterintuitively) that an imperative conventionally represents, or expresses a picture of the world, is said to be offset by its ability to explain a variety of phenomena for which speech act-theoretic accounts are said to lack good explanations (even, in many cases, the bare ability to offer something that might meet basic criteria on what a good explanation should be like). I aim to turn the tables on static accounts. I do this by showing that speech act accounts are capable of giving explanations of phenomena which fans of static accounts have alleged them unable to give. Indeed, for a variety of absolutely fundamental phenomena having to do with the conventional meaning of imperatives (and other types of practical language), speech act accounts provide natural and theoretically satisfying explanations, where a representational account provides none