Classical Truth Research Articles

An experimental study of classical truth logic on multi-propositions consistent and incompatible: Dual-process theories and modal syllogistic of deduction.

This study looked at a classical truth logic of multi-propositions that is new in some ways: [1] Alethic modalities were mixed with logical consistency and incompatibility in a single plate form, i.e., necessary consistency (NC), possible consistency (PC)/ possible incompatibility (PI) and impossible incompatibility (IPI); [2] multi-propositions were judged by individuals as either NC, PC/PI, or IPI; [3] Four quantifiers; All (∀), No (∼∀), Some (∃), and Some Not (∼∃) of four propositional modes and three shapes ([Formula: see text], ▱ and [Formula: see text]) are used to evaluate predictions; and [4] it inspired by multi-propositional of dual-process theories (DPTs) of deduction and modal syllogistic of multi-propositions, from which logicians have derived general hypotheses. HP 1- Individuals will more likely to endorse inferences as PC/PI rather than NC. HP 2: It's easier to calculate that inference has PC/ PI if it has also NC. Generally, logicians predict more endorsing PC for NC than for PI proposition. HP 3: It's easier to calculate that inference is not NC if it is also not PC. Generally, logicians predict more PI than IPI proposition endorses as NC. A modal syllogistic as a classical truth logic is presented by multi-propositions (two premises and one inference), each one from four modes has quantifiers such as universal quantifiers and existential quantifier; ∀, ∼∀, ∃, and ∼ ∃. They were evaluated by a single-mental model (Experiment I) and a multi-mental model (Experiment II). Logicians applied the immediate inference task (IIT), evaluation task (ET), and production task (PT) to evaluate three experiments. The results of the experiments suggested that students mostly endorsed PC/PI inferences over NC inferences. Even when logicians divided PC/PI separately as PC and PI, individuals endorsed PC most likely as compared to NC, and PI than IPI. Logicians also highlighted fallacies that were continuously resisted and endorsed when students were asked to judge multi-propositions that had NC. The purpose of this experimental study is to present a glimpse of students' endorsement of multi-propositions and explain that each individual has a different working memory and intelligence.

How to Conquer the Liar and Enthrone the Logical Concept of Truth

This article informally presents a solution to the paradoxes of truth and shows how the solution solves classical paradoxes (such as the original Liar) as well as the paradoxes that were invented as counterarguments for various proposed solutions (“the revenge of the Liar”). This solution complements the classical procedure of determining the truth values of sentences by its own failure and, when the procedure fails, through an appropriate semantic shift allows us to express the failure in a classical two-valued language. Formally speaking, the solution is a language with one meaning of symbols and two valuations of the truth values of sentences. The primary valuation is a classical valuation that is partial in the presence of the truth predicate. It enables us to determine the classical truth value of a sentence or leads to the failure of that determination. The language with the primary valuation is precisely the largest intrinsic fixed point of the strong Kleene three-valued semantics (LIFPSK3). The semantic shift that allows us to express the failure of the primary valuation is precisely the classical closure of LIFPSK3: it extends LIFPSK3 to a classical language in parts where LIFPSK3 is undetermined. Thus, this article provides an argumentation, which has not been present in contemporary debates so far, for the choice of LIFPSK3 and its classical closure as the right model for the truth predicate. In the end, an erroneous critique of Kripke-Feferman axiomatic theory of truth, which is present in contemporary literature, is pointed out.

The Modal Future

<i>The Modal Future</i>

О трехзначных расширениях логики Клини

The paper is devoted to one of the most famous three-valued systems – Kleene's logic. The expressive capabilities of Kleene's logic and its three-valued expansions are described. We present two results. First, all possible three-valued expansions of Kleene's logic are found up to equivalence with respect to the mutual definability of connectives. It is shown that there are only twelve such expansions. This list includes both logics already known in the literature and completely new ones. For the found expansions, we describe the structure of the lattice ordered relative to the expressive power of its elements. Secondly, for Kleene's logic and its three-valued expansions we find how many extensions each of these logics has in the same language. Kleene's logic has only two proper extensions: the classical and the trivial ones. Generally, a three-valued logic in which Kleene's matrix is definable contains no more than three proper extensions: the classical one, the trivial one, and an intermediate logic, determined by the product of the the original logic's matrix and the matrix of classical logic in the same signature. Intermediate logics exist only for two types of three-valued expansions of Kleene's logic: in expansions equivalent to Łukasiewicz's logic, and in logics whose matrices contain both a bivalent submatrix, the universe of which consists of the classical truth values, and a submatrix, the universe of which consists the intermediate value alone. All three-valued expansions of Kleene's logic that do not preserve the classical values have only one extension of their own – the trivial one.

Dynamic Approximation of Self-Referential Sentences

Abstract Non-classical logic via approximation of self-referential sentences by dynamical systems are consistently presented. The new 6-valued truth values &lt;T, va, A, V, av, F&gt; (here A=Liar, V=TruthTeller) are presented as a function of the classical truth values x i ∈ {0,1}, which resulted in a philosophical standpoint known as Suszko’s Thesis. Three-valued truth tables were created corresponding to Priest’s tables of the same name. In the process of constructing 4-valued truth tables, two more new truth values (va, av) were revealed that do not coincide with the four original ones. Therefore, the closed tables turned out to be 6-valued. Prof Dunn’s 4-valued truth tables are compared with our 4-valued truth tables. De Morgan’s laws are confirmed by six-valued truth tables. Constructed 3-, 4- and 6-valued lattices obeying De Morgan’s laws.

Dunn Semantics for Contra-Classical Logics

In this paper I show, with a rich and systematized diet of examples, that many contra-classical logics can be presented as variants of FDE, obtained by modifying at least one of the truth or falsity conditions of some connective. Then I argue that using Dunn semantics provides a clear understanding of the source of contra-classicality, namely, connectives that have either the classical truth or the classical falsity condition of another connective. This requires a fine-grained analysis of the sorts of modifications that can be made to an evaluation condition, analysis which I offer here as well.

Noncontextual coloring of orthogonality hypergraphs

We discuss representations and colorings of orthogonality hypergraphs in terms of their two-valued states interpretable as classical truth assignments. Such hypergraphs, if they allow for a faithful orthogonal representation, have quantum mechanical realizations in terms of intertwined contexts or maximal observables that are widely discussed as empirically testable criteria for contextuality. A reconstruction is possible for the class of perfectly separable hypergraphs. Colorings can be constructed from a minimal set of two-valued states. Some examples from exempt categories are presented, which either cannot be reconstructed by two-valued states or whose two-valued states cannot yield a chromatic number that is equal to the maximal clique number.

Probabilities with Gaps and Gluts

Belnap-Dunn logic (BD), sometimes also known as First Degree Entailment, is a four-valued propositional logic that complements the classical truth values of True and False with two non-classical truth values Neither and Both. The latter two are to account for the possibility of the available information being incomplete or providing contradictory evidence. In this paper, we present a probabilistic extension of BD that permits agents to have probabilistic beliefs about the truth and falsity of a proposition. We provide a sound and complete axiomatization for the framework defined and also identify policies for conditionalization and aggregation. Concretely, we introduce four-valued equivalents of Bayes’ and Jeffrey updating and also suggest mechanisms for aggregating information from different sources.

О выразительных возможностях отдельных расширений четырехзначной логики Белнапа

Статья посвящена замкнутым классам функций четырехзначной логики. Мы представляем следующие результаты:&#x0D; (1) Базовые операции логики, полученной расширением четырехзначной алгебры Де Моргана оператором конфляции, порождают замкнутый класс всех функций, которые одновременно сохраняют классические истинностные значения и самодвойственны относительно конфляции. Этот класс предполон в классе всех функций, сохраняющих классические истинностные значения.&#x0D; (2) Между замкнутым классом, порожденным базовыми операциями логики истины фон Вригта и классом всех функций, сохраняющих классические истинностные значения, лежит в точности два замкнутых класса. Каждый из них представляет собой класс всех функций, одновременно сохраняющих классические истинностные значения и одно из трехэлементных надмножеств множества классических истинностных значений.&#x0D; (3) Базовые операции тетравалентной модальной логики, полученной расширением четырехзначной алгебры Де Моргана оператором необходимости, порождают замкнутый класс всех функций, которые одновременно сохраняют классические истинностные значения, самодвойственны относительно конфляции, а также сохраняют оба трехэлементных надмножества множества классических истинностных значений. Мы показываем, что данный класс предполон в классе всех функций, которые одновременно сохраняют классические истинностные значения и самодвойственны относительно конфляции. Кроме того, мы демонстрируем, что между этим классом и замкнутым классом, порожденным операциями логики истины фон Вригта, находится в точности один замкнутый класс.&#x0D; Таким образом мы получаем семиэлементную решетку, состоящую из всех возможных четырехзначных расширений тетравалентной модальной логики, которые сохраняют классические истинностные значения.

Making Sense of Shifts in Perspectives: Perceiving and Framing Examples of Interreligious Learning in Indonesia

ABSTRACT This article focuses on aspects of epistemological questions in religious and intercultural studies. It draws on results from research into two interreligious education formats for young adults in Java, Indonesia: ‘Sobat Muda’ in Salatiga, and ‘Sekolah Lintas Iman’ in Yogyakarta. After a reflection on issues of intercultural research design, the article identifies formative influences regarding formation, and changes in perspectives on interreligious relations and perceptions, on the basis of information from respondents participating in those programmes. Observations of a strong connection between the use of the term ‘truth’, with its derivations, and the societal value of harmony in the description of such change processes in Indonesian contexts, lead to an attempt at intercultural translation, carried out as an inquiry into classical truth concepts within the European thought tradition. Inspired by the findings of the study, in conclusion, the term verifiation is introduced, which may prove useful in intercultural epistemological efforts.

Post Post-Truth: Epistemologies of Disintegration and the Praxeology of Truth

Our truth culture has changed. Yet we are not living in a post-truth era but in a truth era – an observation of the ongoing debates shows a proliferation of invocations of truth. This paper argues that in order to grasp this transition, we should not refer to classical truth theories or common oppositions such as knowledge and belief, objectivity and subjectivity. Instead, we should focus on concrete practices in concrete situations: on “doing truth.” This paper introduces the concept of a “praxeology of truth,” which sets out to analyse truth by means of two parameters: “truth scenes” and “truth figures.” In suggesting that to ask about truth is to pose the question of power, it follows Michel Foucault, but it regards the invocation of truth as a technique of identity politics and truth as a social operator.

Reference and Truth

I apply the notions of alethic reference introduced in previous work in the construction of several classical semantic truth theories. Furthermore, I provide proof-theoretic versions of those notions and use them to formulate axiomatic disquotational truth systems over classical logic. Some of these systems are shown to be sound, proof-theoretically strong, and compare well to the most renowned systems in the literature.

Normality operators and classical recapture in many-valued logic

AbstractIn this paper, we use a ‘normality operator’ in order to generate logics of formal inconsistency and logics of formal undeterminedness from any subclassical many-valued logic that enjoys a truth-functional semantics. Normality operators express, in any many-valued logic, that a given formula has a classical truth value. In the first part of the paper we provide some setup and focus on many-valued logics that satisfy some (or all) of the three properties, namely subclassicality and two properties that we call fixed-point negation property and conservativeness. In the second part of the paper, we introduce normality operators and explore their formal behaviour. In the third and final part of the paper, we establish a number of classical recapture results for systems of formal inconsistency and formal undeterminedness that satisfy some or all the properties above. These are the main formal results of the paper. Also, we illustrate concrete cases of recapture by discussing the logics $\mathsf{K}^{\circledast }_{3}$, $\mathsf{LP}^{\circledast }$, $\mathsf{K}^{w\circledast }_{3}$, $\mathsf{PWK}^{\circledast }$ and $\mathsf{E_{fde}}^{\circledast }$, that are in turn extensions of $\mathsf{{K}_{3}}$, $\mathsf{LP}$, $\mathsf{K}^{w}_{3}$, $\mathsf{PWK}$ and $\mathsf{E_{fde}}$, respectively.

Relational similarity-based model of data part 1: foundations and query systems

We present a general rank-aware model of data which supports handling of similarity in relational databases. The model is based on the assumption that in many cases it is desirable to replace equalities on values in data tables by similarity relations expressing degrees to which the values are similar. In this context, we study various phenomena which emerge in the model, including similarity-based queries and similarity-based data dependencies. Central notion in our model is that of a ranked data table over domains with similarities which is our counterpart to the notion of relation on relation scheme from the classical relational model. Compared to other approaches which cover related problems, we do not propose a similarity-based or ranking module on top of the classical relational model. Instead, we generalize the very core of the model by replacing the classical, two-valued logic upon which the classical model is built by a more general logic involving a scale of truth degrees that, in addition to the classical truth degrees 0 and 1, contains intermediate truth degrees. While the classical truth degrees 0 and 1 represent nonequality and equality of values, and subsequently mismatch and match of queries, the intermediate truth degrees in the new model represent similarity of values and partial match of queries. Moreover, the truth functions of many-valued logical connectives in the new model serve to aggregate degrees of similarity. The presented approach is conceptually clean, logically sound, and retains most properties of the classical model while enabling us to employ new types of queries and data dependencies. Most importantly, similarity is not handled in an ad hoc way or by putting a “similarity module” atop the classical model in our approach. Rather, it is consistently viewed as a notion that generalizes and replaces equality in the very core of the relational model. We present fundamentals of the formal model and two equivalent query systems which are analogues of the classical relational algebra and domain relational calculus with range declarations. In the sequel to this paper, we deal with similarity-based dependencies.

Epistemic extensions of combined classical and intuitionistic propositional logic

Logic $L$ was introduced by Lewitzka [7] as a modal system that combines intuitionistic and classical logic: $L$ is a conservative extension of CPC and it contains a copy of IPC via the embedding $\varphi\mapsto\square\varphi$. In this article, we consider $L3$, i.e. $L$ augmented with S3 modal axioms, define basic epistemic extensions and prove completeness w.r.t. algebraic semantics. The resulting logics combine classical knowledge and belief with intuitionistic truth. Some epistemic laws of Intuitionistic Epistemic Logic studied by Artemov and Protopopescu [1] are reflected by classical modal principles. In particular, the implications "intuitionistic truth $\Rightarrow$ knowledge $\Rightarrow$ classical truth" are represented by the theorems $\square\varphi\rightarrow K\varphi$ and $K\varphi\rightarrow\varphi$ of our logic $EL3$, where we are dealing with classical instead of intuitionistic knowledge. Finally, we show that a modification of our semantics yields algebraic models for the systems of Intuitionistic Epistemic Logic introduced in [1].

Nonclassical Probability and Convex Hulls

It is well known that the convex hull of the classical truth value functions contains all and only the probability functions. Work by Paris and Williams has shown that this also holds for various kinds of nonclassical logics too. This note summarises the formal details of this topic and extends the results slightly.

From Bi-facial Truth to Bi-facial Proofs

In their recent paper Bi-facial truth: a case for generalized truth values Zaitsev and Shramko [7] distinguish between an ontological and an epistemic interpretation of classical truth values. By taking the Cartesian product of the two disjoint sets of values thus obtained, they arrive at four generalized truth values and consider two "semi-classical negations" on them. The resulting semantics is used to define three novel logics which are closely related to Belnap's well-known four valued logic. A syntactic characterization of these logics is left for further work. In this paper, based on our previous work on a functionally complete extension of Belnap's logic, we present a sound and complete tableau calculus for these logics. It crucially exploits the Cartesian nature of the four values, which is reflected in the fact that each proof consists of two tableaux. The bi-facial notion of truth of Z&S is thus augmented with a bi-facial notion of proof. We also provide translations between the logics for semi-classical negation and classical logic and show that an argument is valid in a logic for semi-classical negation just in case its translation is valid in classical logic.

Perfect Pavelka Logic

Zadeh's Fuzzy Logic was introduced as a mathematical tool for deduction working with different degrees of truth, instead of the two truth degrees of Classical Logic. The next step taken by Pavelka was to admit assumptions and theorems which are also satisfied only to some truth degree, as well as deduction rules transferring these degrees to the deduced formulas. In the semantics these possibly, but not necessarily, correspond to the degrees of satisfaction of formulas. A significant consequent progress towards this direction was achieved by Hajek's work on Rational Pavelka Logic; it forms formulas with graded truth as couples of a formula and a rational truth value. The success of the Rational Pavelka Logic follows from the properties of the standard MV-algebra, i.e. the real unit interval [0,1] with the Łukasiewicz operations, which was used as its semantical interpretation. The main mathematical result is that the Rational Pavelka Logic is sound and complete in the sense that the syntactical provability degree and the semantical degree of satisfaction coincide. In this paper an alternative to Pavelka's approach is investigated. Instead of the standard MV-algebra, the truth values are taken from a perfect MV-algebra, in particular, Chang's MV-algebra. This is the opposite extreme among MV-algebras, it admits only infinitesimals besides the two classical truth degrees. We argue that such an example also has a motivation in deduction imitating human reasoning. As Chang's MV-algebra is not complete, the provability degree need not exist. Nevertheless, as the main result the following weak completeness theorem is proved: If the provability degree of a formula exists, it coincides with the degree of satisfaction. This result is obtained by adding to Pavelka's original approach a new rule of inference, Hájek's book-keeping axioms and an axiom valid in Chang's MV-algebra. An example that clarifies the differences between Classical Logic, Rational Pavelka Logic and Perfect Pavelka Logic is given, and some new fuzzy rules of inference are introduced.

Knowledge Spaces and the Completeness of Learning Strategies

We propose a theory of learning aimed to formalize some ideas underlying Coquand's game semantics and Krivine's realizability of classical logic. We introduce a notion of knowledge state together with a new topology, capturing finite positive and negative information that guides a learning strategy. We use a leading example to illustrate how non-constructive proofs lead to continuous and effective learning strategies over knowledge spaces, and prove that our learning semantics is sound and complete w.r.t. classical truth, as it is the case for Coquand's and Krivine's approaches.

Bi-facial Truth: a Case for Generalized Truth Values

We explore a possibility of generalization of classical truth values by distinguishing between their ontological and epistemic aspects and combining these aspects within a joint semantical framework. The outcome is four generalized classical truth values implemented by Cartesian product of two sets of classical truth values, where each generalized value comprises both ontological and epistemic components. This allows one to define two unary twin connectives that can be called "semi-classical negations". Each of these negations deals only with one of the above mentioned components, and they may be of use for a logical reconstruction of argumentative reasoning.