Jaroslav Peregrin

The paper presents a demarcation of a “minimalistic” concept of logical form, which nevertheless largely agrees with the way the term “logical form” is commonly used in contemporary logic and philosophy of logic. We see logical forms as formulas of formal languages assigned to (compounds of) sentences of a natural language (perhaps modulo notational variance). We thus reject the views of logical forms as underlying structures of thoughts or of the material reality that surrounds us. The assignment of the forms, we claim, aims at envisaging the logical (especially inferential) properties of the analyzed sentences, arguments, or other texts, as the analyzing formulas wear them, as it were, on their sleeves. Hence we suggest an “expressivist” and a pragmatic understanding of logical forms - they are used to expose (and fix) logical properties of sentences in textual contexts and the way of their employment is determined by the goals of the particular studies.

Recent decades are marked by the upswing of the use of the term “normativity“ not only in philosophical discussions, but increasingly also within reports of empirical scientists. This may invoke the question how far these developments overlap and in how far they go past each other. A significant overlap might lead to an interesting coalescence of the two approaches to norms, which may provide for a ”naturalization” of some philosophical speculations about normativity, putting them on a firmer foundation, while offering the empirical scientists some new impulses for directing their research. In this paper I give an overview of some recent empirical results concerning human normativity and I point out a certain philosophical tradition, rooted especially in the works of Wittgenstein, Sellars and Brandom, which treats normativity so that it becomes more or less compatible with these results.

Brandom’s inferentialism explains meaning in terms of inferential rules. As he insists that “the normative” is not reducible to “the natural,” inferentialism would seem an unlikely ally of naturalism. However, in this paper I suggest that Brandom’s theory of language harbors insights which can promote a naturalistic theory of meaning and language, and that a naturalistic version of Brandom’s inferentialism might have great potential. Also I sketch the lines along which such a theory could be built.

Ve své nové knížce Kauzalita činitele Petr Dvořák argumentuje, že svoboda vůle existuje, a tudíž musíme přijmout nějakou formu indeterminismu; a předkládá návrh odpovídajícího pojmového rámce. Já se naproti tomu domnívám, že ač svoboda vůle skutečně existuje, neměli bychom proto opouštět determinismus; hlásím se tedy k určité formě kompatibilismu. Podle mého druhu kompatibilismu tomu ovšem není tak, že by se svoboda vůle dala vtěsnat do deterministického rámce. Domnívám se, že řešení je v přijetí toho, že při výkladu skutečnosti nevystačíme s jediným pojmovým rámcem – konkrétně že na člověka se můžeme dívat jako na organismus (skrze deterministický a fyzikalistický rámec), ale také jako na osobu (skrze rámec, který je „prodchnut normativitou“).

Ve své polemice s mou recenzí jeho knihy Tomáš Marvan argumentuje, že debatu mezi realismem a relativismem (či konstruktivismem) lze rozřešit, a to prostřednictvím důkazů ve prospěch realismu. V tomto příspěvku vysvětluji, že podle mne realismus nemůže být prokázán, protože to není teze, kterou by bylo možné dokazovat, ale spíše něco jako kantovská „regulativní idea“. In his polemic reply to my review of his book Tomáš Marvan argues that the debate between realism and relativism (or constructivism) can be resolved, especially by means of evidence in favor of realism. In this contribution I explain that according to me realism cannot be demonstrated, because it is not a thesis that could be supported by evidence, but rather something as a Kantian "regulative idea".

This book addresses the hasty development of modern logic, especially its introducing and embracing various kinds of artificial languages and moving from the study of natural languages to that of artificial ones. This shift seemed extremely helpful and managed to elevate logic to a new level of rigor and clarity. However, the change that logic underwent in this way was in no way insignificant, and it is also far from an insignificant matter to determine to what extent the "new logic" only engaged new and more powerful instruments to answer the questions posed by the "old" one, and to what extent it replaced these questions with new ones. Hence, this movement has generated brand new kinds of philosophical problems that have still not been dealt with systematically. Philosophy of Logical Systems addresses these new kinds of philosophical problems that are intertwined with the development of modern logic. Jaroslav Peregrin analyzes the rationale behind the introduction of the artificial languages of logic; classifies the various tools which were adopted to build such languages; gives an overview of the various kinds of languages introduced in the course of modern logic and the motifs of their employment; discusses what can actually be achieved by relocating the problems of logic from natural language into them; and reaches certain conclusions with respect to the possibilities and limitations of this "formal turn" of logic. This book is both an important scholarly contribution to the philosophy of logic and a systematic survey of the standard logical systems that were established during the short history of modern logic.

Logic is usually presented as a tool of rational inquiry; however, many logicians in fact treat logic so that it does not serve us, but rather governs us – as rational beings we are subordinated to the logical laws we aspire to disclose. We denote the view that logic primarily serves us as logica serviens, while denoting the thesis that it primarily governs our reasoning as logica dominans. We argue that treating logic as logica dominans is misguided, for it leads to the idea of a “genuine” logic within a “genuine” language. Instead of this, we offer a naturalistic picture, according to which the only languages that exist are the natural languages and the artificial languages logicians have built. There is, we argue, no language beyond these, especially none that would be a wholesome vehicle of reasoning like the natural languages and yet be transparently rigorous like the artificial ones. Logic is a matter of using the artificial languages as idealized models of the natural ones, whereby we pinpoint the laws of logic by means of zooming in on a reflective equilibrium.

The question how to turn the principles implicitly governing the concept of truth into an explicit definition of the concept hence coalesced with the question how to get a finite grip on the infinity of T-sentences. Tarski's famous and ingenious move was to introduce a new concept, satisfaction, which could be, on the one hand, recursively defined, and which, on the other hand, straightforwardly yielded an explication of truth. A surprising 'by-product' of Tarski's effort to bring truth under control was the breathtaking finding that truth is in a precisely defined sense ineffable, that no non trivial language can contain a truth-predicate which would be adequate for the very 4 language. This implied that truth proved itself to be strangely 'language-dependent': we can have a concept of truth-in-L for any language L, but we cannot have a concept of truth applicable to every language. In a sense, this means, as Quine put it, that truth belongs to "transcendental metaphysics", and Tarski's 'scientific' investigations seem to lead us back towards a surprising proximity of some more traditional philosophical views on truth. 3. TARSKI'S THEORY AS A PARADIGM So far Tarski himself. Subsequent philosophers then had to find out what his considerations of the concept of truth really mean and what are their consequences; and this now seems to be an almost interminable task.

The heyday of discussions initiated by Searle's claim that computers have syntax, but no semantics has now past, yet philosophers and scientists still tend to frame their views on artificial intelligence in terms of syntax and semantics. In this paper I do not intend to take part in these discussions; my aim is more fundamental, viz. to ask what claims about syntax and semantics in this context can mean in the first place. And I argue that their sense is so unclear that that their ability to act as markers within any disputes on artificial intelligence is severely compromised; and hence that their employment brings us nothing more than an illusion of explanation.

In this paper we put forward and defend a view of the nature of logic that we call moderate anti-exceptionalism. In the first part of the paper we focus on the problem of genuine logical validity and consequence. We make use of examples from current debates to show that attempts to pinpoint the one and only authentic logic inevitably either yield irrefutable theories or lead to dead ends. We then outline a thoroughly naturalist account of logical consequence as grounded in rules implicit in human linguistic practices. We insist that there are only two existing kinds of language: natural languages, and artificial languages that have been forged by us. There is thus no room for a "genuine" language and hence for "genuine" logic. We conclude that though logical theories are established—and are liable to criticism—in a similar fashion as those of the sciences, and in this sense logic is not exceptional, to fulfill its mission logic must lay a claim to normative authority over our argumentation and reasoning, which makes its methodology somewhat special. Logical theory is not meant to provide just an explanation, the standards it establishes serve also as a tool, providing for a reinforcement of our rational communication.

Nedávné vědecké poznatky týkající se lidského vnímání a lidského konání naznačují, že nejenom není konání bez vnímání, ale že není ani vnímání bez konání. Zcela se mění pohled na to, jak lidé vnímají ; a objevují se dokonce i extrémní názory, že vnímání a konání jsou vlastně jednou a toutéž věcí. Podobně se v důsledku zkoumání motivačních struktur stojících v základu tvorby teorií rozmývá ostrou hranici mezi teorií a praxí. Zdá se mi, že tohle všechno je poněkud překvapivá voda na mlýn filosofického pragmatismu.

Člověk se od jiných živočišných druhů odlišuje mnoha způsoby, k nejpodstatnějším z nichž patří rozum, jazyk a také schopnost řídit se pravidly. V tomto textu argumentuji, že je to především ta poslední schopnost, která je klíčová a bez které jsou ty další nepředstavitelné. Člověk je společenská bytost nejenom v tom smyslu, že žije ve společenstvích, ale i v tom, že tato společenství jsou strukturována složitým pletivem pravidel, která zásadním způsobem determinují modus vivendi lidí, kteří je tvoří, a v důsledku toho determinují i člověka jako takového. Soustava pravidel může vytvořit jistý „vnitřní prostor" - to jest tato pravidla můžeme přijímat a tím vstoupit do tohoto prostoru, nebo je můžeme jenom zaznamenávat. Dialektika těchto dvou postojů nám umožňuje nahlédnout, že ač je normativní rozměr pro člověka jakožto společenskou bytost naprosto klíčový a těžko postižitelný běžnými vědeckými metodami „nezúčastněného pozorování", není tento normativní rozměr ničím esoterickým, něčím, co by bylo z hlediska vědy pochybné.

Do mathematical expressions have intensions, or merely extensions? If we accept the standard account of intensions based on possible worlds, it would seem that the latter is the case – there is no room for nontrivial intensions in the case of non-empirical expressions. However, some vexing mathematical problems, notably Gödel’s Second Incompleteness Theorem, seem to presuppose an intensional construal of some mathematical expressions. Hence, can we make room for intensions in mathematics? In this paper we argue that this is possible, provided we give up the standard approach to intensionality based on possible worlds.

Davidson’s anomalous monism is based on the assumption that a human being can be described or accounted for in two very different ways, using two very different and indeed incommensurable conceptual frameworks, namely the physicalistic vocabulary of science and the mentalistic vocabulary employed by the ‘theories’ we make about each other when we interact and communicate. Also Sellars maintains that we have two alternative pictures of the world and especially of us humans as its parts, namely the scientific image and the manifest image. At first sight, the views of the two philosophers may seem quite similar; however, the true extent of this apparent similarity is worth exploring. To that end, in this paper we tackle the following questions: Are Sellars’ reasons for claiming the irreducibility of his manifest image to the scientific image the same or similar to those that Davidson has for asserting the irreducibility of his mentalistic idiom to the scientific one? Is the normativity informing Sellars’ manifest image of the same kind as that informing Davidson’s mentalistic idiom? Do the notions of rationality considered by Sellars and Davidson coincide?

Saul Kripke ’s book Naming and Necessity (which first appeared in 1972 as a paper within a volume on natural language semantics1) is felt, by many linguists and philosophers, as a milestone of the semantic analysis of natural language. Prior to it, many semanticists took for granted that the meaning of any expression must be a two-level matter, consisting of something of the kind of what Frege called Sinn and Bedeutung or what Carnap christened as intension and extension. The first of the components is what the speaker knows when she understands the expression (and the knowledge of which is independent of any knowledge of facts external to the language in question), while the second amounts to some kind of chunk of the real world which gets denoted or referred to by the expression. Thus, the intension of the king of France is what you get to know as soon as you come to understand the phrase, and the extension is what (if anything) happens to be picked out by the intension in the actual world in the actual moment. This is to say that an expression gets to into the contact with its extension only via the intension (which we can imagine also as a kind of a criterion for picking up the thing). Intension, then, is what amounts to the meaning of the expression in the intuitive sense of the word2. Now Kripke’s considerations challenged this very two-level structure of meaning: he argued that especially proper names get their semantics via a direct, inmediated contact with the world – that their meaning does not mediate their contact with a thing, but directly is the thing. This may be not so surprising in case of proper names (after all, it is even disputable whether they can be counted to the language – for you cannot find them in dictionaries), but Kripke went on to argue that the same holds also for some other expressions, especially natural kind terms such as “cow” or “water”. Kripke’s argumentation is concise and flattening; and it has been provoking a lot of discussions..

Existuje obrovské množství definic logiky; avšak je tu jistá jednotící myšlenka, která se proplétá většinou z nich, a to je ta, že logika nám má pomoci klasifikovat úsudky, způsoby argumentace či důkazy na „správné“ a „nesprávné“, a tímto způsobem nám má pomoci lépe „usuzovat“. A protože úsudek či argumentační schéma je věcí kroku od nějakých premis k nějakému závěru a jeho správnost můžeme vyjadřovat také tak, je jeho závěr odvoditelný z jeho premis či z nich vyplývá . Toto úzké pojetí logiky nás vede přímo k jejímu modernímu chápání jakožto zkoumání vyplývání či odvoditelnosti. Nazvěme takové kritické zkoumání argumentací, úsudků či odvození základní agendou logiky