Epistemic Language Research Articles

Stable acceptance for mighty knowledge

Drawing on the puzzling behavior of ordinary knowledge ascriptions that embed an epistemic (im)possibility claim, we tentatively conclude that it is untenable to jointly endorse (i) an unfettered classical logic for epistemic language, (ii) the general veridicality of knowledge ascription, and (iii) an intuitive ‘negative transparency’ thesis that reduces knowledge of a simple negated ‘might’ claim to an epistemic claim without modal content. We motivate a strategic trade-off: preserve veridicality and (generalized) negative transparency, while abandoning the general validity of contraposition. We criticize various approaches to incorporating veridicality into domain semantics, a paradigmatic ‘information-sensitive’ framework for capturing negative transparency and, more generally, the non-classical behavior of sentences with epistemic modals. We then present a novel information-sensitive semantics that successfully executes our favored strategy: stable acceptance semantics, extending a vanilla bilateral state-based semantics for epistemic modals with a knowledge operator loosely inspired by the defeasibility theory of knowledge.

Epistemic language in news headlines shapes readers’ perceptions of objectivity

How we reason about objectivity-whether an assertion has a ground truth-has implications for belief formation on wide-ranging topics. For example, if someone perceives climate change to be a matter of subjective opinion similar to the best movie genre, they may consider empirical claims about climate change as mere opinion and irrelevant to their beliefs. Here, we investigate whether the language employed by journalists might influence the perceived objectivity of news claims. Specifically, we ask whether factive verb framing (e.g., "Scientists know climate change is happening") increases perceived objectivity compared to nonfactive framing (e.g., "Scientists believe [...]"). Across eight studies (N = 2,785), participants read news headlines about unique, noncontroversial topics (studies 1a-b, 2a-b) or a familiar, controversial topic (climate change; studies 3a-b, 4a-b) and rated the truth and objectivity of the headlines' claims. Across all eight studies, when claims were presented as beliefs (e.g., "Tortoise breeders believe tortoises are becoming more popular pets"), people consistently judged those claims as more subjective than claims presented as knowledge (e.g., "Tortoise breeders know…"), as well as claims presented as unattributed generics (e.g., "Tortoises are becoming more popular pets"). Surprisingly, verb framing had relatively little, inconsistent influence over participants' judgments of the truth of claims. These results demonstrate how, apart from shaping whether we believe a claim is true or false, epistemic language in media can influence whether we believe a claim has an objective answer at all.

A logical modeling of the Yōkai board game

We present an epistemic language for representing an artificial player’s beliefs and actions in the context of the Yōkai board game. Yōkai is a cooperative game which requires a combination of Theory of Mind (ToM), temporal and spatial reasoning to be played effectively by an artificial agent. We show that the language properly accounts for these three dimensions and that its satisfiability problem is NP-complete. This opens up the possibility of exploiting SAT techniques for automating reasoning of an artificial player in the context of the Yōkai board-game.

Culturally constituted universals: Evidential basis of belief matters.

Differences in the sequence with which children pass the tasks in Wellman and Liu's (2004) theory of mind (ToM) battery is increasingly bringing into question the universal and cultural specifics of children's developing understanding of others' minds. Children from China, Iran, and Turkey pass the knowledge access (KA) task of the battery earlier than they pass the diverse beliefs (DB) task (e.g., Selcuk etal., 2018). This pattern is the reverse of what has been documented with children from Australia and the US (e.g., Peterson etal., 2005). This paper presents three studies with Turkish samples that explore the possible reasons for developmental sequence and performance differences in the ToM battery. Study 1 investigated Turkish-speaking adults' judgments of appropriateness for different epistemic verbs as used in the DB and false belief (FB) tasks. Study 2 investigated whether adults' performance (i.e., accuracy, reaction time) on FB tasks were affected by culturally preferred uses of these verbs. Collectively these studies showed that adults found different epistemic language ("guess," "think," and the Turkish-specific "falsely think") to be appropriate for different belief-based tasks. However, there was no difference in adults' performance based on epistemic language. In Study 3, Turkish-speaking preschoolers' performance in belief-related tasks based on variations in epistemic language and epistemic features (i.e., presence of evidence) was investigated. Among five modifications, Turkish children benefited only from a modification that involved the manipulation of the epistemological basis for ambiguous beliefs (i.e., visual evidence for belief). RESEARCH HIGHLIGHTS: Turkish adults find different epistemic language ("guess," "think," and the Turkish-specific "falsely-think") to be appropriate for different belief-based tasks (diverse and false belief tasks). Turkish adults' performance on false belief (FB) tasks is not affected by epistemic language. Turkish children perform better in diverse beliefs (DB) task if an epistemological basis for ambiguous beliefs (i.e., visual evidence for either belief) is provided.

Inquisitive logic as an epistemic logic of knowing how

In this paper, we present an alternative interpretation of propositional inquisitive logic as an epistemic logic of knowing how. In our setting, an inquisitive logic formula α being supported by a state is formalized as knowing how to resolve α (more colloquially, knowing how α is true) holds on the S5 epistemic model corresponding to the state. Based on this epistemic interpretation, we use a dynamic epistemic logic with both know-how and know-that operators to capture the epistemic information behind the innocent-looking connectives in inquisitive logic. We show that the set of valid know-how formulas corresponds precisely to the inquisitive logic. The main result is a complete axiomatization with intuitive axioms using the full dynamic epistemic language. Moreover, we show that the know-how operator and the dynamic operator can both be eliminated without changing the expressivity over models, which is consistent with the modal translation of inquisitive logic existing in the literature. We hope our framework can give an intuitive alternative interpretation to various concepts and technical results in inquisitive logic, and also provide a powerful and flexible tool to handle both the inquisitive reasoning and declarative reasoning in an epistemic context.

De Re Updates

In this paper, we propose a lightweight yet powerful dynamic epistemic logic that captures not only the distinction between de dicto and de re knowledge but also the distinction between de dicto and de re updates. The logic is based on the dynamified version of an epistemic language extended with the assignment operator borrowed from dynamic logic, following the work of Wang and Seligman (Proc. AiML 2018). We obtain complete axiomatizations for the counterparts of public announcement logic and event-model-based DEL based on new reduction axioms taking care of the interactions between dynamics and assignments.

Revisiting the epistemic gap: It’s not the thought that counts

ABSTRACT This paper revisits the longstanding observation that children produce modal verbs (e.g., must, could) with their root meanings (e.g., abilities, obligations) by age 2, typically a year or more earlier than with their epistemic meanings (e.g., inferences). Established explanations for this “Epistemic Gap” argue that epistemic language production is delayed because small children can only reason about root meanings. However, root and epistemic uses of modal verbs also differ syntactically and in input representation. We present a corpus study on 17 English-learning children and their input, exploring early productions with both epistemic modal verbs and grammatically simpler and more frequent epistemic adverbs (e.g., maybe, probably). Results show that children use remarkably adult-like epistemic adverb sentences from even before age 2, when they are only producing modal verbs with root meanings. The Epistemic Gap is not well explained by general conceptual advancements. Instead, our data suggest input attestation and ease of form-to-meaning mapping may influence early child epistemic language. These findings are furthermore consistent with cross-linguistic differences in the timing of first epistemic uses of modal verbs, and with recent advancements in our understanding of infant and toddler modal reasoning abilities.

A geometria nos anos finais do Ensino Fundamental: uma análise de referenciais curriculares sob a perspectiva do enfoque ontossemiótico

Apresenta-se, neste artigo, uma análise em referenciais curriculares no que se refere aos conhecimentos geométricos a serem desenvolvidos nos anos finais do Ensino Fundamental. É parte integrante de uma pesquisa que está em andamento que tem como objetivo investigar possibilidades da constituição de um currículo para a Geometria nos anos finais do Ensino Fundamental, na região de abrangência da 36ª Coordenadoria Regional de Educação (CRE) do Estado do Rio Grande do Sul, tomando como referência os constructos do Enfoque Ontossemiótico do Conhecimento e da Instrução Matemática (EOS). A análise toma como suporte elementos da Análise Textual Discursiva e como referência a Idoneidade Epistêmica do EOS. Inicialmente se destaca a análise epistêmica produzida no documento que apresenta a Base Nacional Comum Curricular- BNCC, no que se refere aos conhecimentos geométricos e, em seguida, a análise realizada no documento que apresenta a proposta curricular de um município pertencente a 36ª CRE, tomando como referência a BNCC. Resultados apontam a presença, na BNCC, de modo equitativo, dos componentes epistêmicos situações-problemas, linguagem, regras, argumentos e relações. Na Proposta Curricular analisada foi possível perceber o encaminhamento de um trabalho com a Geometria focada em situações envolvendo grandezas e medidas, com pouca ênfase em situações envolvendo os objetos geométricos e suas propriedades. Ademais, a BNCC aponta para um trabalho com a geometria das transformações, além de aspectos formais de estudo dos objetos geométricos, que não estão presentes na Proposta Curricular. Destaca-se que o documento analisado se encontra em processo de reestruturação.

Dynamic term-modal logics for first-order epistemic planning

Many classical planning frameworks are built on first-order languages. The first-order expressive power is desirable for compactly representing actions via schemas, and for specifying quantified conditions such as ¬∃xblocks_door(x). In contrast, several recent epistemic planning frameworks are built on propositional epistemic logic. The epistemic language is useful to describe planning problems involving higher-order reasoning or epistemic goals such as Ka¬problem.This paper develops a first-order version of Dynamic Epistemic Logic (DEL). In this framework, for example, ∃xKx∃yblocks_door(y) is a formula. The formalism combines the strengths of DEL (higher-order reasoning) with those of first-order logic (lifted representation) to model multi-agent epistemic planning. The paper introduces an epistemic language with a possible-worlds semantics, followed by novel dynamics given by first-order action models and their execution via product updates. Taking advantage of the first-order machinery, epistemic action schemas are defined to provide compact, problem-independent domain descriptions, in the spirit of PDDL.Concerning metatheory, the paper defines axiomatic normal term-modal logics, shows a Canonical Model Theorem-like result which allows establishing completeness through frame characterization formulas, shows decidability for the finite agent case, and shows a general completeness result for the dynamic extension by reduction axioms.

Hermeneutics vs. Genealogy: Brandom’s Cloak or Nietzsche’s Quilt?

ABSTRACT This article examines genealogical investigations in an attempt to explain what they are, how they work, and what purpose they serve. It is a critique of Robert Brandom’s view of genealogists as naïve semanticists who believe that normative thinking, as it relates to all forms of epistemic inquiry and language use, is reducible to naturalistic causes. This reduction, Brandom claims, is hopelessly misguided and semantically incoherent since genealogies are not epistemically neutral in that “they count no more and no less,” as Habermas put it, than the traditional accounts of moral phenomena that they seek to replace. Nietzsche’s “story” of the origin of guilt in On the Genealogy of Morals is thus not even a useful fiction but merely meaningless. My analysis shows that Brandom’s understanding of genealogy is rather simplistic. While genealogists are naturalists insofar as they attempt to discover the specific historical causes that gave rise to current normative practices, they are neither reductive empiricists nor first-stage semanticists, as Brandom calls them, but multidimensional power-pragmatists.

Exploiting Belief Bases for Building Rich Epistemic Structures

We introduce a semantics for epistemic logic exploiting a belief base abstraction. Differently from existing Kripke-style semantics for epistemic logic in which the notions of possible world and epistemic alternative are primitive, in the proposed semantics they are non-primitive but are defined from the concept of belief base. We show that this semantics allows us to define the universal epistemic model in a simpler and more compact way than existing inductive constructions of it. We provide (i) a number of semantic equivalence results for both the basic epistemic language with "individual belief" operators and its extension by the notion of "only believing", and (ii) a lower bound complexity result for epistemic logic model checking relative to the universal epistemic model.

Epistemology for the Rest of the World

The editors and contributors for this excellent and timely volume have provided a great service to epistemology. Over the last thirty years or so, epistemology has taken somewhat of a ‘linguistic turn’. This is perhaps most clearly seen in the development of views like contextualism, contrastivism, and the ambiguity theory of ‘know’, all of which seek to explain certain persistent epistemological puzzles by examining the word ‘know’ in addition to, or instead of, the concepts of knowing and knowledge. Despite this shift to a greater focus on epistemic language, epistemology continues to be, in many ways, a quintessentially armchair subdiscipline. And many discussions in epistemology have been hampered (even if this hampering hasn’t always been acknowledged) by a lack of information about how language users around the world talk about and conceptualize the epistemic. This volume marks an important step in rectifying the situation. The twelve chapters (along with an accompanying ‘Manifesto’ and Introduction) give analytic epistemology a wealth of cross-linguistic data and related theorizing. Most chapters deal with the words ‘know’ and ‘knowledge’, but there are other contributions, such as Shane Ryan and Chienkuo Mi's fascinating examination of how Confucius’ philosophy contributes to virtue epistemology (ch. 4), and Lisa Matthewson and Jennifer Glougie's rigorous examination of the concepts of justification and truth across a half dozen or so languages (ch. 7).

Propositional Epistemic Logics with Quantification Over Agents of Knowledge

The paper presents a family of propositional epistemic logics such that languages of these logics are extended by quantification over modal (epistemic) operators or over agents of knowledge and extended by predicate symbols that take modal (epistemic) operators (or agents) as arguments. Denote this family by \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\). There exist epistemic logics whose languages have the above mentioned properties (see, for example Corsi and Orlandelli in Stud Log 101:1159–1183, 2013; Fitting et al. in Stud Log 69:133–169, 2001; Grove in Artif Intell 74(2):311–350, 1995; Lomuscio and Colombetti in Proceedings of ATAL 1996. Lecture Notes in Computer Science (LNCS), vol 1193, pp 71–85, 1996). But these logics are obtained from first-order modal logics, while a logic of \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\) can be regarded as a propositional multi-modal logic whose language includes quantifiers over modal (epistemic) operators and predicate symbols that take modal (epistemic) operators as arguments. Among the logics of \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\) there are logics with a syntactical distinction between two readings of epistemic sentences: de dicto and de re (between ‘knowing that’ and ‘knowing of’). We show the decidability of logics of \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\) with the help of the loosely guarded fragment (LGF) of first-order logic. Namely, we generalize LGF to a higher-order decidable loosely guarded fragment. The latter fragment allows us to construct various decidable propositional epistemic logics with quantification over modal (epistemic) operators. The family of this logics coincides with \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\). There are decidable propositional logics such that these logics implicitly contain quantification over agents of knowledge, but languages of these logics are usual propositional epistemic languages without quantifiers and predicate symbols (see Grove and Halpern in J Log Comput 3(4):345–378, 1993). Some logics of \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\) can be regarded as counterparts of logics defined in Grove and Halpern (J Log Comput 3(4):345–378, 1993). We prove that the satisfiability problem for these logics of \({\mathcal {P}\mathcal {E}\mathcal {L}}_{({ QK})}\) is Pspace-complete using their counterparts in Grove and Halpern (J Log Comput 3(4):345–378, 1993).

Left hemisphere EEG coherence in infancy predicts infant declarative pointing and preschool epistemic language

Pointing plays a central role in preverbal communication. While imperative pointing aims at influencing another person’s behavior, declarative gestures serve to convey epistemic information and to share interest in an object. Further, the latter are hypothesized to be a precursor ability of epistemic language. So far, little is known about their underlying brain maturation processes. Therefore, the present study investigated the relation between brain maturation processes and the production of imperative and declarative motives as well as epistemic language in N = 32 infants. EEG coherence scores were measured at 14 months, imperative and declarative point production at 15 months and epistemic language at 48 months. Results of correlational analyses suggest distinct behavioral and neural patterns for imperative and declarative pointing, with declarative pointing being associated with the maturation of the left hemisphere. Further, EEG coherence measures of the left hemisphere at 14 months and declarative pointing at 15 months are related to individual differences in epistemic language skills at 48 months, independently of child IQ. In regression analyses, coherence measures of the left hemisphere prove to be the most important predictor of epistemic language skills. Thus, neural processes of the left hemisphere seem particularly relevant to social communication.

Common Knowledge in Email Exchanges

We consider a framework in which a group of agents communicates by means of emails, with the possibility of replies, forwards and blind carbon copies (BCC). We study the epistemic consequences of such email exchanges by introducing an appropriate epistemic language and semantics. This allows us to find out what agents learn from the emails they receive and to determine when a group of agents acquires common knowledge of the fact that an email was sent. We also show that in our framework from the epistemic point of view the BCC feature of emails cannot be simulated using messages without BCC recipients.

A Quantum Computational Semantics for Epistemic Logical Operators. Part II: Semantics

By using the abstract structures investigated in the first Part of this article, we develop a semantics for an epistemic language, which expresses sentences like “Alice knows that Bob does not understand that π is irrational”. One is dealing with a holistic form of quantum computational semantics, where entanglement plays a fundamental role; thus, the meaning of a global expression determines the contextual meanings of its parts, but generally not the other way around. The epistemic situations represented in this semantics seem to reflect some characteristic limitations of the real processes of acquiring information. Since knowledge is not generally closed under logical consequence, the unpleasant phenomenon of logical omniscience is here avoided.

On the definability of simulation and bisimulation in epistemic logic

We explore when finite epistemic models are definable up to simulation or bisimulation, either over the basic multi-agent epistemic language L or over its extension L-C with common knowledge operators. Our main results are the following: (1) Bisimulation to finite epistemic states (i.e. pointed models) is not definable in L. (2) Global bisimulation to finite epistemic models is definable using model validity in L. (3) Simulation by finite epistemic states is not always definable, even over L-C. (4) We identify a class of epistemic models called well-multifounded for which simulation to finite epistemic states is definable over L. The first two results contrasts with that of van Benthem that finite epistemic states are definable up to bisimulation in L-C by so-called characteristic formulae. Our results have applications in the logical specification of multi-agent systems. Characteristic formulae, which define states up to bisimulation, fully capture all modally definable properties of models, and can for example be used to give complete calculi for validity over fixed structures. Meanwhile, simulation is a 'substructure' relation that is appropriate for epistemic logic, as it preserves positive existential formulae. Simulation formulae are useful in giving a dynamic description of models subject to epistemic actions.

Reasoning about minimal anonymity in security protocols

Anonymity, as an instance of information hiding, is one of the security properties intensively studied nowadays due to its applications to various fields such as electronic voting, electronic commerce, electronic mail, and so on.This paper presents a comprehensive study on minimal anonymity properties in security protocols. In order to reach this objective, an epistemic language and logic to reason about anonymity properties in security protocols, are provided. Agent states are endowed with facts derived from actions performed by agents in protocol executions, and an inference system is proposed. To define minimal anonymity, an observational equivalence is used, which is shown to be decidable in deterministic polynomial time. We distinguish between various forms of sender and receiver anonymity with respect to two types of observers: honest agents and the intruder. A large spectrum of relationships between these anonymity concepts is then derived. It is also shown that an anonymous action in a security protocol under a passive intruder might not be anonymous in the same security protocol if the intruder is active, and vice-versa.The decidability and complexity status of the anonymity concepts introduced in the paper is finally investigated. Thus, it is shown that minimal anonymity is undecidable in unrestricted security protocols, is NEXPTIME-complete in bounded security protocols, and is NP-complete in 1-session bounded security protocols.

Reverse Engineering Epistemic Evaluations*

What is the function of words like ‘irrational’ as used in ordinary epistemic evaluations? I’m thinking of simple evaluations: criticism like ‘Smith’s belief that Obama’s a Muslim is irrational’ or praise like ‘Green’s belief that all humans are mortal is rational’. We don’t make such claims just for the sake of it, just for fun, or for no reason at all. So what is the real point or purpose of this epistemically evaluative aspect of our linguistic practice? It must have some utility, but what? What would we lose if epistemically evaluative words suddenly disappeared from our vocabulary?1 The question requires some motivation, since discovering a word’s function doesn’t necessarily call for armchair philosophy. Some words might ∗I pronounce it, when speaking English, like this: sin ·on dor ·uh·mudge·uh. The question of this paper thus contrasts with the timeworn questions of how to give necessary and sufficient conditions for this or that philosophically interesting property. There are, however, a few excellent philosophical explorations of the function of this or that philosophically interesting word or concept. In philosophy of logic and language, Quine offered an elegantly simple insight about the utility of the truth predicate which precipitated the contemporary development of deflationism about truth; see Quine (1970), Leeds (1978), Horwich (1990/98), and Field (1994). In metaphysics, a series of recent papers on modality have broached the fascinating issue of the function of modal concepts; see Kment (2006), chapter 5 of Williamson (2007), and Divers (2010). In epistemology, there is Edward Craig’s wonderful and underappreciated book, Knowledge and the State of Nature, Craig (1990). Some recent work by Steven Reynolds, brought to my attention only after this paper was given at the Rutgers Epistemology Conference, is closely related to Craig’s project; see Reynolds (2002). Though Craig and Reynolds write about knowledge rather than rationality or justification, there are obvious common themes and specific points of contact between their views and the view I will be developing. The most notable common theme is the general importance we assign to the role of testimony in the function epistemic language. One major difference, since they write about knowledge and not rationality, is that their views are not designed to explain the puzzle I will be raising shortly.

Question–answer games

We propose strategic games wherein the strategies consist of players asking each other questions and answering those questions. We study simplifications of such games wherein two players simultaneously ask each other a question that the opponent is then obliged to answer. The motivation for our research is to model conversation including the dynamics of questions and answers, to provide new links between game theory and dynamic logics of information, and to exploit the dynamic/strategic structure that, we think, lies implicitly inside epistemic models for epistemic languages, and to make that structure an explicit subject of logical study. Our main contributions are: the notion of a two-person question-answer game with information goals, the existence and computation of equilibria for these games, the correspondence with Bayesian games and their equilibria, and a connection between logic and game theory namely the existence of equilibria for positive goal formulae.