Jiri Raclavsky

Zatímco v případě otázek rigidity singulárních termínů panuje obecná shoda, v případě rigidity predikátů tomu tak překvapivě není. Záměrem této statě je opřít distinkci rigidní / nerigidní o jasné pojmy, jmenovitě o pojem reference v určité sémantické teorii. V důsledku toho lze podat rigorózní definici pojmu rigidního designátoru individua. Tato definice je pak přímočaře adaptovatelná pro případ pojmu rigidního designátoru třídy individuí (apod.). Tímto je dosaženo nejen obecnosti, ale i vnitřní jednoty teorie rigidity.

Tato stať je zamýšlena jako úvod do spojité problematiky explikace pravdivosti a sémantic-kých paradoxů, které onu explikaci pronásledují. Tyto paradoxy jsou viděny jako prostředek ukázání, že nedostatečně promyšlená explikace našeho pojmu pravdivosti (významu pravdi-vostního predikátu) je explikací nevyhovující. Poté jsou předvedeny rysy obou klasických přístupů, Russellovy teorie typů a Tarského hierarchie metajazyků. Nakonec jsou podány zá-kladní ideje hlavních názorových škol, které přišly poté.

The paper focuses on treating partiality within Tichý’s logical system. Tichý’s logic is two-valued and type-theoretic. His simple theory of types (and the deduction system for it) accepts both total and partial functions. Tichý’s late framework is explicitly ramified. So-called constructions (roughly: algorithms) construct, e.g., values of functions at arguments; in some cases, however, they do not construct anything at all. This special partiality phenomenon is discussed in the second part of the paper.

This paper follows in Pavel Tichý’s concept of distinguishing between trivial (i.e. constant) and non-trivial properties. This classification has been extended by Pavel Cmorej who distinguished two kinds of non-trivial properties, namely purely empirical and partly essential (which are partly empirical) properties (partly essential property is essential for certain individual(s), but that it is not for other(s)). The present study provides rigorous formal definitions of trivial / non-trivial, essential / non-essential, and purely empirical / partly essential / purely essential properties with respect to the possible partiality of these properties. In addition, a definition of trivially void properties completing the classification of the kinds of properties to form a quadruplet is proposed. Furthermore, the introduction of the concept of accidental properties gives rise to another (yet not equivalent) quadruplet: purely accidental / partly essential (i.e. partly accidental) / purely essential / void properties.

Two kinds of individuals are distinguished: abstract and concrete. Whereas abstract individuals belong to our conceptual sphere, concrete individuals (i.e. particulars) individuate the world of matter. A subject investigating the external world projects abstract individuals onto concrete ones. The proposal offers a solution to various metaphysical and epistemological puzzles concerned with individuals, e.g., the Ship of Theseus, the Polish Logician, problems with reidentification, or proper names.

Anotace Following Carnap's Principle of Subject Matter, Pavel Tichý proposed a methodological principle I call the "Denotational Principle of Aboutness". It says that expressions are about their denotata. Denotata are modelled as possible world intensions or (common) extensions. Nearly the same principle was recently defended by Marie Duží and Pavel Materna under the name the "Parmenides Principle". However, Duží and Materna did not react to Tichý's late proposal which I call the "Constructional Principle of Aboutness". It says that the subject matter of expressions consists not in their denotata but their meanings. The meanings are explicated by Tichý, and also by Duží and Materna, as so-called constructions; constructions are complex entities akin to algorithms, they construct intensions or extensions. In this paper, I argue in favour of the Constructional Principle of Aboutness. I show that there are not only single arguments, but whole net of methodological principles which support it. This is why the topic largely transcends the debate among Tichý's followers.

The approach of Transparent Intensional Logic to truth differs significantly from rivalling approaches. The notion of truth is explicated by a three-level system of notions whereas the upper-level notions depend on the lower-level ones. Truth of possible world propositions lies in the bottom. Truth of hyperintensional entities – called constructions – which determine propositions is dependent on it. Truth of expressions depends on truth of their meanings; the meanings are explicated as constructions. The approach thus adopts a particular hyperintensional theory of meanings; truth of extralinguistic items is taken as primary. Truth of expressions is also dependent, either explicitly or implicitly, on language (its notion is thus also explicated within the approach). On each level, strong and weak variants of the notions are distinguished because the approach employs the Principle of Bivalence which adopts partiality. Since the formation of functions and constructions is non-circular, the system is framed within a ramified type theory having foundations in simple theory of types. The explication is immune to all forms of the Liar paradox. The definitions of notions of truth provided here are derivation rules of Pavel Tichý's system of deduction.

It is already known that Fitch's paradox of knowability can be solved by typing knowledge. I differentiate two kinds of such typing, Tarskian and Russellian, and focus on the latter which is framed within the ramified theory of types. My main aim is to other a defence of the approach against recently raised criticism. The key justification is provided by the Vicious Circle Principle which governs the very formation of propositions and thus also intensional operators, including the operator of knowledge.

Pavel Tichy originally published his interesting conception of possible worlds in 1968. Even though he modified it over the following twenty five years, its core remained unchanged. None of his thirty journal papers or books containing the notion of possible worlds was a study in metaphysics, Tichy (and most of his followers) always introduced the notion in the context of other investigations where he applied his Transparent intensional logic either to the semantic analysis of natural language or explications of other notions. Tichy presented his conceptions using rather short descriptions occurring on a number of places; his proposal appears not only fragmentary but also somehow incoherent. The main contribution of this paper is thus not only a complete survey of Tichy's development of his conception but also a certain completion of the very proposal.

Williamson, Linsky, Paseau and others proposed a solution to Church- Fitch's knowability paradox that is based on typing knowledge; however, it received some criticism. Carrara and Fassio objected that the approach has no paradox-independent motivation, it is thus ad hoc. In the first part of the paper, I dismiss such criticism by carefully stating typing approach principles that are based on non-circular formation of propositions and intensional operators operating on them. In the second part of the paper, I demonstrate that the firm foundation of the approach prevents the variants of the paradox by Florio, Murzi and Jago that were developed as allegedly unresolvable by typing knowledge. The revenge form of Church-Fitch's knowability paradox, which had been proposed by Williamson, Hart, Carrara and Fassio, fares badly as well, since it is likewise based on violation of reasonable typing rules.

Two kinds of individuals are distinguished: abstract and concrete. Whereas abstract individuals belong to our conceptual sphere, concrete individuals (i.e. particulars) individuate the world of matter. A subject inquiring the external world projects abstract individuals onto the concrete ones (i.e. pieces of matter). Our theory offers a solution to various ontological and epistemological puzzles concerned with individuals, e.g., the Ship of Theseus, Polish Logician, problems with reidentification, or proper names.

The Barber paradox is often introduced as a popular version of Russell’s paradox, though some experts have denied their similarity, evencalling the Barber paradox a pseudoparadox. In the first part of thepaper, I demonstrate mainly that in the standard (Quinean) defini-tion of a paradox the Barber paradox is a clear-cut example of a non-paradox. Despite some outward similarities, it differs radically fromRussell’s paradox. I also expose many other differences. In the secondpart of the paper, I examine a probable source of the paradoxicality ofthe Barber paradox, which is found in a certain ambivalence in terms ofmeaning. The two different readings of the crucial phrase yield distinctexistential assumptions which produce the paradoxical conclusion.

I examine the familiar quadruple of categorical statements “Every F is/is not G.”, “Some F is/is not G.” as well as the quadruple of their modal versions “Necessarily, every F is/is not G.”, “Possibly, some F is/is not G.”. I focus on their existential import and its impact on the resulting Squares of Opposition. Though my construal of existential import follows modern approach, I add some extra details which are enabled by framing my definition of existential import within expressively rich higher-order partial type logic. As regards the modal categorical statements, I find that so-called void properties bring existential import to them, so they are the only properties which invalidate subalternation, and thus also contrariety and subcontrariety, in the corresponding Square of Opposition.

In this study, we examine modern reading of the Square of Opposition by means of Tichý's Transparent intensional logic. Explicit use of possible world semantics helps us to sharply discriminate between standard and modal readings of categorial statements. We thus get two basic versions of the Square, whereas the Modal Square has not been fully introduced in the contemporary debate yet. Some properties ascribed by mediaeval logicians to the Square require a shift from its Standard to Modal version. Not inevitably, because for each of the two squares there exists its mate which can be easily confused with it. We thus investigate four distinct squares. The discrimination between the initial and modified versions of the Standard and Modal Square leads to better knowledge of the Square as well as a solution of various puzzles often mentioned in recent literature.

The problem of hyperintensional contexts, and the problem of logical omniscience, shows the severe limitation of possible-worlds semantics which is employed also in standard epistemic logic. As a solution, we deploy here hyperintensional semantics according to which the meaning of an expression is an abstract structured algorithm, namely Tichý's construction. Constructions determine the denotata of expressions. Propositional attitudes are modelled as attitudes towards constructions of truth values. Such a model of belief is, of course, inferentially restrictive. We therefore also propose a model of implicit knowledge, which is the collection of a possible agent's explicit beliefs which are related through a derivation system mastered by the agent. A derivation system consists of beliefs and derivation rules by means of which the agent may derive beliefs different from the beliefs she is actually related to. Conditions imposed on the set of base beliefs and the set of rules capture the limitations of the agent's deriving capabilities.