Grammatical theories of Scalar Implicatures make use of an exhaustivity operator exh, which asserts the conjunction of the prejacent with the negation of excludable alternatives. We present a new Grammatical theory of Scalar Implicatures according to which exh is replaced with pex, an operator that contributes its prejacent as asserted content, but the negation of scalar alternatives at a non-at-issue level of meaning. We show that by treating this non-at-issue level as a presupposition, this theory resolves a number of empirical (...) challenges faced by the old formulation of exh (as well as by standard neo-Gricean theories). The empirical challenges include projection of scalar implicatures from certain embedded environments (‘some under some’ sentences, some under negative factives), their restricted distribution under negation, and the existence of common ground-mismatching and oddness-inducing implicatures. We argue that these puzzles have a uniform solution given a pex-based Grammatical theory of implicatures and some independently motivated principles concerning presupposition projection, cancellation and accommodation. (shrink)

The paper surveys the currently available axiomatizations of common belief (CB) and common knowledge (CK) by means of modal propositional logics. (Throughout, knowledge- whether individual or common- is defined as true belief.) Section 1 introduces the formal method of axiomatization followed by epistemic logicians, especially the syntax-semantics distinction, and the notion of a soundness and completeness theorem. Section 2 explains the syntactical concepts, while briefly discussing their motivations. Two standard semantic constructions, Kripke structures and neighbourhood structures, are introduced in Sections (...) 3 and 4, respectively. It is recalled that Aumann's partitional model of CK is a particular case of a definition in terms of Kripke structures. The paper also restates the well-known fact that Kripke structures can be regarded as particular cases of neighbourhood structures. Section 3 reviews the soundness and completeness theorems proved w.r.t. the former structures by Fagin, Halpern, Moses and Vardi, as well as related results by Lismont. Section 4 reviews the corresponding theorems derived w.r.t. the latter structures by Lismont and Mongin. A general conclusion of the paper is that the axiomatization of CB does not require as strong systems of individual belief as was originally thought- only monotonicity has thusfar proved indispensable. Section 5 explains another consequence of general relevance: despite the "infinitary" nature of CB, the axiom systems of this paper admit of effective decision procedures, i.e., they are decidable in the logician's sense. (shrink)

Temporal epistemic logics are known, from results of Halpern and Vardi, to have a wide range of complexities of the satisfiability problem: from PSPACE, through non-elementary, to highly undecidable. These complexities depend on the choice of some key parameters specifying, inter alia, possible interactions between time and knowledge, such as synchrony and agents' abilities for learning and recall. In this work we develop practically implementable tableau-based decision procedures for deciding satisfiability in single-agent synchronous temporal-epistemic logics with interactions between time (...) and knowledge. We discuss some complications that occur, even in the single-agent case, when interactions between time and knowledge are assumed and show how the method of incremental tableaux can be adapted to work in EXPSPACE, respectively 2EXPTIME, for these logics, thereby also matching the upper bounds obtained for them by Halpern and Vardi. (shrink)

[English] This paper aims to discuss ten traditional and contemporary methodological paradigms in African philosophy, and demonstrates how they may apply to African environmental ethics research. The methods include: Ethno-philosophy, Sage Philosophy, Conversational Philosophy, Conceptual Mandelanization, Eco-Afrocentricism, Indigenous Language Analysis, Eco-Afro-feminism, Conceptual Decolonization, Storytelling Philosophy, and Cultural Adaptationism. The significance and limitations of the methodologies are highlighted. The concept and principles of African environmental ethics are analyzed and discussed to facilitate an understanding of the conceptual frameworks that underpin the methodologies. (...) In conclusion, the discourse demonstrates that environmental ethics research in Africa should be based on African philosophical methodologies so as to facilitate production of research that will be relevant in African contexts. -/- [Annang] N̄wed nduongo ami ayem ibene nwọ́d mme n̄kaan nne mfa usung unam nduongo ke vilọsọvi Afrịke , nne nte amọ ekeme iwam unam nduongo mbanga ido ukpeme nkan-nkuk ke Afrịke. Mme usung unam nduongo ami nsehe ade ami: vilọsọvi mben ufọk, vilọsọvi n̄kan ideen, vilọsọvi nneme, vilọsọvi Mandela, “Eco-Afrocentricism”, nduongore usem utiit ajid, vilọsọvi ibaan Afrịke, vilọsọvi mkpọk-nyak, vilọsọvi n̄ke, nne ukpep ido idung agwo. N̄wed ami abene awọd mme ikek nne nde mem idem usung nduongo ami. N̄wed ami atang mkpọ abanga se ido ukpeme nkan-nkuk ke Afrịke anwongo nne mme itai amọ, nne nte amọ ewam mbon nduongo ediọhọ nnanga ekpekakpa ibọrọ nduongo amọ. Ke n̄suuk ikọ, ukpep ami mkpọ abene awọd ate ke ekpena ekama usung nduongo vilọsọvi Afrịke enam nduongo ebanga ido ukpeme nkan-nkuk ke Afrịke man ibọrọ nduongo asanga akekem nne se adiiwam Afrịke. (shrink)