This monograph discusses the sources for ancient propositional logic, mainly in Sextus Empiricus and Diogenes Laertius bk. VII. It is argued that most of the sources in Sextus which have hitherto been taken to be sources for Stoic logic either do not report Stoic logic at all or report pre-Chrysippean Stoic logic. These texts report (in the first case) a group labelled the Dialecticians whose most prominent members were Diodorus Cronus and Philo or else (in the (...) second case) early Stoic logicians heavily influenced by the Dialecticians. The texts discussed concern the theory of signs, the theory of proof and the classifications of propositions and of arguments. (shrink)

ABSTRACT: This paper traces the evidence in Galen's Introduction to Logic (Institutio Logica) for a hypothetical syllogistic which predates Stoic propositional logic. It emerges that Galen is one of our main witnesses for such a theory, whose authors are most likely Theophrastus and Eudemus. A reconstruction of this theory is offered which - among other things - allows to solve some apparent textual difficulties in the Institutio Logica.

The first monograph on Stoic modal logic. Part 1 discusses the Stoic notion of propositions (assertibles, axiomata): their definition; their truth-criteria; the relation between sentence and proposition; propositions that perish; propositions that change their truth-value; the temporal dependency of propositions; the temporal dependency of the Stoic notion of truth; pseudo-dates in propositions. Part 2 discusses Stoic modal logic: the Stoic definitions of their modal notions (possibility, impossibility, necessity, non-necessity); the logical relations between the modalities; modalities (...) as properties of propositions; contingent propositions; the relation between the Stoic modal notions and those of Diodorus Cronus and Philo of Megara; the role of ‘external hindrances’ for the modalities; the temporal dependency of the modalities; propositions that change their modalities; the principle that something possible can follow from something impossible; the interpretations of the Stoic modal system by B. Mates, M. Kneale, M. Frede, J. Vuillemin and M. Mignucci are evaluated. -/- For a shorter, updated, English version of Part 1 of the book see S. Bobzien, ‘Stoic Logic’, in K. Algra et al. (eds), The Cambridge History of Hellenistic Philosophy, Cambridge 1999, 92-157. For a shorter, updated, English version of Part 2 of the book see S. Bobzien 'Chrysippus' Modal Logic and its Relation to Philo and Diodorus', in K. Doering / Th. Ebert (eds) Dialektiker und Stoiker (Stuttgart 1993) 63-84. (shrink)

The Stoic philosopher Chrysippus wrote extensively on the liar paradox, but unfortunately the extant testimony on his response to the paradox is meager and mainly hostile. Modern scholars, beginning with Alexander Rüstow in the first decade of the twentieth century, have attempted to reconstruct Chrysippus? solution. Rüstow argued that Chrysippus advanced a cassationist solution, that is, one in which sentences such as ?I am speaking falsely? do not express propositions. Two more recent scholars, Walter Cavini and Mario Mignucci, have (...) rejected Rüstow's thesis that Chrysippus used a cassationist approach. Each has proposed his own thesis about Chrysippus? solution. I argue that Rüstow's view is fundamentally correct, and that the cassationist thesis gains greater plausibility when viewed in light of a passage in Sextus Empiricus? Adversus mathematicos that the previous commentators have ignored, and when understood within the broader context of Stoic logical theory and philosophy of language. I close with a brief remark on the significance of Chrysippus? work for the modern debate on the semantic paradoxes. (shrink)

This paper discusses the reports in Diogenes Laertius and in Sextus Empiricus concerning the classification of propositions. It is argued that the material in Sextus uses a source going back to the Dialectical school whose most prominent members were Diodorus Cronus and Philo of Megara. The material preserved in Diogenes Laertius, on the other hand, goes back to Chrysippus.

One of the most intriguing claims of Stoic logic is Chrysippus's denial of the modal principle that the impossible does not follow from the possible. Chrysippus's argument against this principle involves the idea that some propositions are ?destroyed? or ?perish?. According to the standard interpretation of Chrysippus's argument, propositions cease to exist when they are destroyed. Ide has presented an alternative interpretation according to which destroyed propositions persist after destruction and are false. I argue that Ide's alternative interpretation as (...) well as some versions of the standard interpretation conflict with Stoic doctrines about the nature of propositions. I propose another version of the standard interpretation based on Frede's account of the Stoic theory of the proposition. I hold that this version of the standard interpretation both escapes Ide's objections and is consistent with Stoic logic and philosophy of language. (shrink)

ABSTRACT: The modal systems of the Stoic logician Chrysippus and the two Hellenistic logicians Philo and Diodorus Cronus have survived in a fragmentary state in several sources. From these it is clear that Chrysippus was acquainted with Philo’s and Diodorus’ modal notions, and also that he developed his own in contrast of Diodorus’ and in some way incorporated Philo’s. The goal of this paper is to reconstruct the three modal systems, including their modal definitions and modal theorems, and to (...) make clear the exact relations between them; moreover, to elucidate the philosophical reasons that may have led Chrysippus to modify his predessors’ modal concept in the way he did. It becomes apparent that Chrysippus skillfully combined Philo’s and Diodorus’ modal notions, with making only a minimal change to Diodorus’ concept of possibility; and that he thus obtained a modal system of modalities (logical and physical) which fit perfectly fit into Stoic philosophy. (shrink)

We argue that the extant evidence for Stoic logic provides all the elements required for a variable-free theory of multiple generality, including a number of remarkably modern features that straddle logic and semantics, such as the understanding of one- and two-place predicates as functions, the canonical formulation of universals as quantified conditionals, a straightforward relation between elements of propositional and first-order logic, and the roles of anaphora and rigid order in the regimented sentences that express multiply general propositions. (...) We consider and reinterpret some ancient texts that have been neglected in the context of Stoic universal and existential propositions and offer new explanations of some puzzling features in Stoic logic. Our results confirm that Stoic logic surpasses Aristotle’s with regard to multiple generality, and are a reminder that focusing on multiple generality through the lens of Frege-inspired variable-binding quantifier theory may hamper our understanding and appreciation of pre-Fregean theories of multiple generality. (shrink)

Chrysippus of Soli (c. 280/77–208/5 BC) was a most multilateral stoic philosopher; he earned the title of Second Founder of Stoa. A prolific writer (he has written much more than any other stoic philosopher, but none of his works have survived except as fragments), Chrysippus expanded the fundamental doctrines of Zeno of Citium, the founder of the school. Chrysippus excelled in logic, the theory of knowledge, physics and ethics. He created an original system of propositional logic in (...) order to better understand the causal interrelations of events in the universe. He adhered to a deterministic view of fate, but nevertheless sought a role for personal freedom in thought and action. Ethics, he thought, depended on understanding the nature of the universe, and he taught a therapy of extirpating the passions which depress the soul. He initiated the success of Stoicism as one of the most influential philosophical movements in the Greek and Roman world. (shrink)

ABSTRACT: A comprehensive introduction to ancient (western) logic from earliest times to the 6th century CE, with an emphasis on topics which may be of interest to contemporary logicians. Content: 1. Pre-Aristotelian Logic 1.1 Syntax and Semantics 1.2 Argument Patterns and Valid Inference 2. Aristotle 2.1 Dialectics 2.2 Sub-sentential Classifications 2.3 Syntax and Semantics of Sentences 2.4 Non-modal Syllogistic 2.5 Modal Logic 3. The early Peripatetics: Theophrastus and Eudemus 3.1 Improvements and Modifications of Aristotle's Logic 3.2 Prosleptic Syllogisms 3.3 Forerunners (...) of Modus Ponens and Modus Tollens 3.4 Wholly Hypothetical Syllogisms 4. Diodorus Cronus and Philo the Logician 5. The Stoics 5.1 Logical Achievements Besides Propositional Logic 5.2 Syntax and Semantics of Complex Propositions 5.3 Arguments 5.4 Stoic Syllogistic 5.5 Logical Paradoxes 6. Epicurus and the Epicureans 7. Later Antiquity. (shrink)

This book treats ancient logic: the logic that originated in Greece by Aristotle and the Stoics, mainly in the hundred year period beginning about 350 BCE. Ancient logic was never completely ignored by modern logic from its Boolean origin in the middle 1800s: it was prominent in Boole’s writings and it was mentioned by Frege and by Hilbert. Nevertheless, the first century of mathematical logic did not take it seriously enough to study the ancient logic texts. A renaissance in ancient (...) logic studies occurred in the early 1950s with the publication of the landmark Aristotle’s Syllogistic by Jan Łukasiewicz, Oxford UP 1951, 2nd ed. 1957. Despite its title, it treats the logic of the Stoics as well as that of Aristotle. Łukasiewicz was a distinguished mathematical logician. He had created many-valued logic and the parenthesis-free prefix notation known as Polish notation. He co-authored with Alfred Tarski’s an important paper on metatheory of propositional logic and he was one of Tarski’s the three main teachers at the University of Warsaw. Łukasiewicz’s stature was just short of that of the giants: Aristotle, Boole, Frege, Tarski and Gödel. No mathematical logician of his caliber had ever before quoted the actual teachings of ancient logicians. -/- Not only did Łukasiewicz inject fresh hypotheses, new concepts, and imaginative modern perspectives into the field, his enormous prestige and that of the Warsaw School of Logic reflected on the whole field of ancient logic studies. Suddenly, this previously somewhat dormant and obscure field became active and gained in respectability and importance in the eyes of logicians, mathematicians, linguists, analytic philosophers, and historians. Next to Aristotle himself and perhaps the Stoic logician Chrysippus, Łukasiewicz is the most prominent figure in ancient logic studies. A huge literature traces its origins to Łukasiewicz. -/- This Ancient Logic and Its Modern Interpretations, is based on the 1973 Buffalo Symposium on Modernist Interpretations of Ancient Logic, the first conference devoted entirely to critical assessment of the state of ancient logic studies. (shrink)

ABSTRACT: The 3rd BCE Stoic logician "Chrysippus says that the number of conjunctions constructible from ten propositions exceeds one million. Hipparchus refuted this, demonstrating that the affirmative encompasses 103,049 conjunctions and the negative 310,952." After laying dormant for over 2000 years, the numbers in this Plutarch passage were recently identified as the 10th (and a derivative of the 11th) Schröder number, and F. Acerbi showed how the 2nd BCE astronomer Hipparchus could have calculated them. What remained unexplained is why (...) Hipparchus’ logic differed from Stoic logic, and consequently, whether Hipparchus actually refuted Chrysippus. This paper closes these explanatory gaps. (1) I reconstruct Hipparchus’ notions of conjunction and negation, and show how they differ from Stoic logic. (2) Based on evidence from Stoic logic, I reconstruct Chrysippus’ calculations, thereby (a) showing that Chrysippus’ claim of over a million conjunctions was correct; and (b) shedding new light on Stoic logic and – possibly – on 3rd century BCE combinatorics. (3) Using evidence about the developments in logic from the 3rd to the 2nd centuries, including the amalgamation of Peripatetic and Stoic theories, I explain why Hipparchus, in his calculations, used the logical notions he did, and why he may have thought they were Stoic. OPEN ACCESS LINK. (shrink)

ABSTRACT: In this paper I argue (i) that the hypothetical arguments about which the Stoic Chrysippus wrote numerous books (DL 7.196) are not to be confused with the so-called hypothetical syllogisms" but are the same hypothetical arguments as those mentioned five times in Epictetus (e.g. Diss. 1.25.11-12); and (ii) that these hypothetical arguments are formed by replacing in a non-hypothetical argument one (or more) of the premisses by a Stoic "hypothesis" or supposition. Such "hypotheses" or suppositions differ from (...) propositions in that they have a specific logical form and no truth-value. The reason for the introduction of a distinct class of hypothetical arguments can be found in the context of dialectical argumentation. The paper concludes with the discussion of some evidence for the use of Stoic hypothetical arguments in ancient texts. (shrink)

This paper contends that Stoic logic (i.e. Stoic analysis) deserves more attention from contemporary logicians. It sets out how, compared with contemporary propositional calculi, Stoic analysis is closest to methods of backward proof search for Gentzen-inspired substructural sequent logics, as they have been developed in logic programming and structural proof theory, and produces its proof search calculus in tree form. It shows how multiple similarities to Gentzen sequent systems combine with intriguing dissimilarities that may enrich contemporary (...) discussion. Much of Stoic logic appears surprisingly modern: a recursively formulated syntax with some truth-functional propositional operators; analogues to cut rules, axiom schemata and Gentzen’s negation-introduction rules; an implicit variable-sharing principle and deliberate rejection of Thinning and avoidance of paradoxes of implication. These latter features mark the system out as a relevance logic, where the absence of duals for its left and right introduction rules puts it in the vicinity of McCall’s connexive logic. Methodologically, the choice of meticulously formulated meta-logical rules in lieu of axiom and inference schemata absorbs some structural rules and results in an economical, precise and elegant system that values decidability over completeness. (shrink)

ABSTRACT: A comprehensive introduction to ancient (western) logic from earliest times to the 6th century CE, with an emphasis on topics which may be of interest to contemporary logicians.

At Varro LL VI.56 and SE M 8.275-276, we find reports of the Stoic view that children and articulate non-rational animals such as parrots cannot genuinely speak. Absent from these testimonia is the peculiar case of the superficiality of the actor’s speech, which appears in one edition of the unstable text of PHerc 307.9 containing fragments of Chrysippus’ Logical Investigations. Commentators who include this edition of the text in their discussions of the Stoic theory of speech do not (...) offer a univocal account of the superficiality of the parrot’s, the child’s, and the actor’s speech. In this paper, I offer a reconstruction of the Stoic account of genuine and superficial speech and show that not only is there an account of superficial speech that univocally explains the superficiality of the speech of parrots, children, and actors, but that this account challenges traditional assumptions about the entities at the heart of the Stoic theory of language—lekta. It will turn out that genuine speech is the expression of a lekton by way of performing a speech act, and that this account of superficial speech can be used to explain other linguistic phenomena that are of interest to the Stoics, such as sentences in insoluble sophisms and sentences containing demonstratives that do not refer to anything in the subject term. Importantly, my reconstruction shows, against the near consensus view of lekta, that lekta do not primarily explain what makes an utterance meaningful. Rather, they primarily explain what makes an utterance an instance of genuine speech. (shrink)

ABSTRACT: This paper collects the evidence in Ammonius' surviving works for elements of a propositional logic, coming to the conclusion that Ammonius had a theory of hypothetical syllogisms in the tradition of Aristotle and the Peripatetics, with Platonic elements mixed in, and using some Stoic elements, but not a propositional logic in the narrower sense as we find it in Stoic logic.

"Collection de fragments et de témoignages sur la logique et la physique de Chrysippe de Soles, en Cilicie, "second fondateur" du stoïcisme au IIIe siècle av. J.-C. Chrysippe rédigea environ 750 livres dont il ne subsiste que des citations dans les ouvrages d'auteurs postérieurs.

ABSTRACT: An introduction to Stoic logic. Stoic logic can in many respects be regarded as a fore-runner of modern propositional logic. I discuss: 1. the Stoic notion of sayables or meanings (lekta); the Stoic assertibles (axiomata) and their similarities and differences to modern propositions; the time-dependency of their truth; 2.-3. assertibles with demonstratives and quantified assertibles and their truth-conditions; truth-functionality of negations and conjunctions; non-truth-functionality of disjunctions and conditionals; language regimentation and ‘bracketing’ devices; Stoic (...) basic principles of propositional logic; 4. Stoic modal logic; 5. Stoic theory of arguments: two premisses requirement; validity and soundness; 6. Stoic syllogistic or theory of formally valid arguments: a reconstruction of the Stoic deductive system, which consisted of accounts of five types of indemonstrable syllogisms, which function as nullary argumental rules that identify indemonstrables or axioms of the system, and four deductive rules (themata) by which certain complex arguments can be reduced to indemonstrables and thus shown to be formally valid themselves; 7. arguments that were considered as non-syllogistically valid (subsyllogistic and unmethodically concluding arguments). Their validity was explained by recourse to formally valid arguments. (shrink)

Two literal quotations from Chrysippus’ On Possibles, preserved in Plutarch’s On the Contradictions of the Stoics, seem to contradict the Stoic thesis of the isotropy of the void. According to this thesis the void is an infinite undifferentiated expanse whose center is marked by, and coincides with, the position of the world. Since there is nothing else outside the world, the cohesive force that pervades it is sufficient on its own to guarantee the quasi–indestructibility of the trans–cyclical διακόσμησις and (...) the eternity of the οὐσία. Conversely, in these two quotations Chrysippus maintains that there is a central διαφορά equipped with causal force. This seems to imply the anisotropy of the void. Chrysippus’s view here is also at odds with another official Stoic thesis, i.e. that the incorporeal is causally inert. In this paper it will be argued that there is in fact no contradiction, because, in those two quotations, Chrysippus consciously develops a cosmological hypothesis in order to resolve a difficulty concerning the role of fire during the universal conflagration. Chrysippus’ solution to this difficulty belongs to modal logic and consists in distinguishing between the actual universe and the possible ones. (shrink)

ABSTRACT: A detailed presentation of Stoic logic, part one, including their theories of propositions (or assertibles, Greek: axiomata), demonstratives, temporal truth, simple propositions, non-simple propositions(conjunction, disjunction, conditional), quantified propositions, logical truths, modal logic, and general theory of arguments (including definition, validity, soundness, classification of invalid arguments).

The early Greek Stoics were the first philosophers to recognize the object of normal human perception as predicative or propositional in nature. Fundamentally we do not perceive qualities or things, but situations and things happening, facts. To mark their difference from Plato and Aristotle, the Stoics adopted phantasia as their word for perception.

This chapter contains sections titled: Introduction The Stoic Logical System Conclusion Bibliography.

This paper deals with Aristotelian and Stoic logic. In the first part the author writes about the history of logic and shows, why Stoic logic had not been studied properly from the Middle Ages up to the beginning of the 20th century, when an increasing interest in the study of Stoic logic is visible. The paper describes the character of Aristotelian and Stoic logic respectively. Stoic logic is first introduced as a system of propositional (...) logic. On this basis a complementarity between the two logical systems of Antiquity is stated. The ways to support the thesis that Stoic logic involved some features of predicative logic are shown at the end of the first part. The ways in which the two rival logical systems were perceived by the authors of the first centuries A. D., namely Galen and Boethius, is described in the second part. Galen is seen as the first to develop an objective synthesis of the two systems. In his Eisagogé dialektiké he tries to show the goals of both rival logical systems. Boethius, in his De hypotheticis syllogismis, is also combining the Aristotelian and the Stoic logic. However, his synthesis is different from Galen's because Boethius probably forms the synthesis unknowingly and indirectly through compiling his confused sources. (shrink)

The Philosophy of Chrysippus is a reconstruction of the philosophy of an eminent Stoic philosopher, based upon the fragmentary remains of his voluminous writings. Chrysippus of Cilicia, who lived in a period that covers roughly the last three-quarters of the third century B.C., studied philosophy in Athens and upon Cleanthes’ death became the third head of the Stoa, one of the four great schools of philosophy of the Hellenistic period. Chrysippus wrote a number of treatises in each of the (...) major departments of philosophy, logic, physics, and ethics. Much of his fame derived from his acuteness as a logician, but his importance for Stoic philosophy generally was acknowledged in antiquity in the saying, “Had there been no Chrysippus, there would be no Stoa.” Previous accounts of Chrysippus’ philosophy, including Émile Bréhier’s study, the only work in this century which had sought to deal with Chrysippus’ philosophy alone, blurred the distinctive contributions of Chrysippus to Stoic philosophy and failed to bring to light the peculiar features in his thought. The vagueness in these accounts resulted in large measure from the assumption that if an ancient author ascribed a doctrine to “the Stoics” or “Stoicism”, one could infer that the doctrine belonged to Chrysippus. Professor Gould works from the more circumspect methodological principle that unless an ancient author explicitly ascribes a doctrine to Chrysippus, his testimony cannot be used in reconstructing Chrysippus’ philosophy. Working with those of the fragments in Hans von Arnim’s collection, Stoicorum Veterum Fragmenta, which are explicitly Chrysippean in the sense suggested, Mr. Gould has worked out an account of Chrysippus’ views in the fields of logic, natural philosophy, and ethics. In order that Chrysippus’ thought might be viewed in context Mr. Gould provides a background picture by describing the third century milieu in which the Stoic philosopher worked. This follows an account of Chrysippus’ life and reputation in antiquity and a description of modern assessments of Chrysippus’ position in the Stoa. In his account of Chrysippus’ philosophy Mr. Gould frequently introduces comparisons and contrasts with Plato and Aristotle to help emphasize the continuity between Hellenic and early Hellenistic philosophy. Finally, in a concluding chapter, the author shows that the dominant themes in Chrysippus’ philosophy, while not exhibiting a thoroughly well-knit system, nevertheless are woven together into a remarkably comprehensive whole, which must have been extraordinarily impressive in antiquity. (shrink)

This paper shows that, for the Hertz–Gentzen Systems of 1933, extended by a classical rule T1 and using certain axioms, all derivations are analytic: every cut formula occurs as a subformula in the cut’s conclusion. Since the Stoic cut rules are instances of Gentzen’s Cut rule of 1933, from this we infer the decidability of the propositional logic of the Stoics. We infer the correctness for this logic of a “relevance criterion” and of two “balance criteria”, and hence (...) that a particular derivable sequent has no derivation that is “normal” in the sense that the first premiss of each cut is cut-free. We also infer that Cut is not admissible in the Stoic system, based on the standard Stoic axioms, the T1 rule and the instances of Cut with just two antecedent formulae in the first premiss. OPEN ACCESS. (shrink)

In he Problems of Philosophy and other works of the same period, Russell claims that every proposition must contain at least one universal. Even fully general propositions of logic are claimed to contain “abstract logical universals”, and our knowledge of logical truths claimed to be a species of a priori knowledge of universals. However, these views are in considerable tension with Russell’s own philosophy of logic and mathematics as presented in Principia Mathematica. Universals generally are qualities and relations, but if, (...) for example, PM’s disjunction (∨) is a relation, what is it a relation between? There is no obvious answer to this given Russell’s other philosophical commitments at this time, although hints are left in some of the pre-PM manuscripts. In this paper, I explore this tension in Russell's philosophy and relate it to developments both before and after Problems. (shrink)

Resumen Atendiendo a la lógica estándar, solo uno de los cinco indemostrables propuestos por Crisipo de Solos es realmente indemostrable. Sus otros cuatro esquemas son demostrables en tal lógica. La pregunta, por tanto, es: si cuatro de ellos no son verdaderamente indemostrables, por qué Crisipo consideró que sí lo eran. López-Astorga mostró que si ignoramos el cálculo proposicional estándar y asumimos que una teoría cognitiva contemporánea, la teoría de la lógica mental, describe correctamente el razonamiento humano, se puede entender por (...) qué Crisipo pensó que todos sus indemostrables eran tan básicos. No obstante, en este trabajo trato de argumentar que la teoría de la lógica mental no es el único marco que puede explicar esto. En concreto, sostengo que otra importante teoría sobre el razonamiento en el presente, la teoría de los modelos mentales, también puede ofrecer una explicación al respecto.According to standard logic, only one of the five indemonstrables proposed by Chrysippus of Soli is actually indemonstrable. The other four schemata are demonstra-ble in that logic. The question hence is, if four of them are not really indemonstrable, why Chrysippus considered them to be so. López-Astorga showed that, if we ignore standard propositional calculus and assume that a current cognitive theory, the mental logic theory, truly describes human reasoning, it can be explained why Chrysippus thought that all of his indemonstrables were so basic. However, in this paper, I try to argue that the mental logic theory is not the only framework that can account for that. In particular, I hold that another important reasoning theory at present, the mental models theory, can offer an explanation in that regard as well. (shrink)

ABSTRACT: Recently a bold and admirable interpretation of Chrysippus’ position on the Sorites has been presented, suggesting that Chrysippus offered a solution to the Sorites by (i) taking an epistemicist position1 which (ii) made allowances for higher-order vagueness. In this paper I argue (i) that Chrysippus did not take an epistemicist position, but − if any − a non-epistemic one which denies truth-values to some cases in a Sorites-series, and (ii) that it is uncertain whether and how he made allowances (...) for higher-order vagueness, but if he did, this was not grounded on an epistemicist position. (shrink)

A common reaction to Hegel’s suggestion that we collapse Kant’s distinction between form and content is that, since such a move would also deprive us of any way of distinguishing the merely logical from the real possibility of our concepts, it is incoherent and ought to be rejected. It is true that these two distinctions are intimately related in Kant, such that if one goes, the other does as well. But it is less obvious that giving them up as Kant (...) conceives them is as incoherent a proposal as many of Hegel’s critics think. It has been the point of a recent account of Hegel’s idealism to demonstrate that his critique of Kant’s dichotomy between form and content or concept and intuition does not commit him to the view that human cognition is materially creative of its content in the manner of a God-like or intuitive intellect—does not, in other words, signify a return to a pre-Critical metaphysics. This is the interpretative stance I adopt here as well, in hope of giving defenders of Kant reasons for taking Hegel more seriously. (shrink)

Lives of the stoics (Zeno, Aristo, Herillus, Cleanthes, Sphaerus, Chrysippus) on philosophy -- Logic and theory of knowledge -- Perception, knowledge, and sceptical attack -- The stoic-academic debate and Cicero's testimony -- Conceptions and rationality -- Physics -- Theology -- Bodily and non-bodily realities -- Structures and powers -- The soul -- Fate -- Ethics -- The general account in Diogenes Lartius -- The account preserved by Stobaeus -- The account in Cicero on goals -- Other evidence for (...) class='Hi'>stoic ethics -- Passions and the goal : criticism within the stoic school and the evidence of Galen -- A critique from the academic-peripatetic point of view -- Pyrrhonist critique of basic ethical concepts -- Later stoic ethics : a sampler -- Musonius Rufus -- Seneca -- Epictetus. (shrink)

Greek antiquity saw the development of two distinct systems of logic: Aristotle’s theory of the categorical syllogism and the Stoic theory of the hypothetical syllogism. Some ancient logicians argued that hypothetical syllogistic is more fundamental than categorical syllogistic on the grounds that the latter relies on modes of propositional reasoning such asreductio ad absurdum. Peripatetic logicians, by contrast, sought to establish the priority of categorical over hypothetical syllogistic by reducing various modes of propositional reasoning to categorical form. (...) In the 17th century, this Peripatetic program of reducing hypothetical to categorical logic was championed by Gottfried Wilhelm Leibniz. In an essay titledSpecimina calculi rationalis, Leibniz develops a theory of propositional terms that allows him to derive the rule ofreductio ad absurdumin a purely categorical calculus in which every proposition is of the formA is B. We reconstruct Leibniz’s categorical calculus and show that it is strong enough to establish not only the rule ofreductio ad absurdum, but all the laws of classical propositional logic. Moreover, we show that the propositional logic generated by the nonmonotonic variant of Leibniz’s categorical calculus is a natural system of relevance logic known as RMI$_{{}_ \to ^\neg }$. (shrink)

In this extended essay, I argue that Frege plagiarized the Stoics --and I mean exactly that-- on a large scale in his work on the philosophy of logic and language as written mainly between 1890 and his death in 1925 (much of which published posthumously) and possibly earlier. I use ‘plagiarize' (or 'plagiarise’) merely as a descriptive term. The essay is not concerned with finger pointing or casting moral judgement. The point is rather to demonstrate carefully by means of detailed (...) evidence that there are numerous (over a hundred) and extensive parallels both in formulation and --more importantly-- in content between the Stoics and Frege, parallels so plentiful that one would be hard pressed to brush them off as coincidence. These parallels include several that appear to occur in no other modern works that were published before Frege’s own and were accessible to him. Additionally, a cluster of corroborating historical data is adduced to support the suggestion, showing how easy it would have to been for Frege to plagiarize the Stoics. This (first) part of the essay is easy to read and vaguely entertaining, or so I hope. -/- (Corrigendum: At school, Frege likely had seven, not ten, years of intensive Latin and four years of intensive ancient Greek courses.). (shrink)

Chrysippus claims that some propositions perish. including some true conditionals whose consequent is impossible and antecedent is possible, to which he appeals against Diodorus?s Master Argument. On the standard interpretation. perished propositions lack truth values. and these conditionals are true at the same time as their antecedents arc possible and consequents impossible. But perished propositions are false, and Chrysippus?s conditionals are true when their antecedent and consequent arc possible, and false when their antecedent is possible and consequent impossible. The claim (...) of the Master Argument that Chrysippus rejects, then, is stronger ihan usually supposed. (shrink)

In this paper, I attempt to explain one of the most controversial views attributed to the Stoic Chrysippus: that the impossible can follow from the possible. My solution finds in Chrysippus a distinction later made by the medieval logician John Buridan: that between being possible (there being a state of affairs that may occur) and being possibly-true (there being some proposition whose truth-conditions are that state of affairs). Buridan and Chrysippus have radically opposing views on the nature of propositions. (...) What their conceptions share is the conclusion that at least some propositions must be contingent beings. They argue for this while maintaining a rigorous commitment to the view that propositions are strictly bivalent. In 2. I explain the Chrysippean passage in terms of a distinction Buridan makes explicitly. In 3. I show how the distinction follows implicitly from the Stoic theory of quantification. In 4. I compare the modality with other aspects of Stoic logic. In 5. I discuss how the distinction behaves in the future tense. (shrink)

The Stoics are traditionally regarded as the founders of propositional logic. However, this is not entirely correct. They developed a theory of inference from signs (omens). And their theory became a continuation of the logical technique of Babylonian divination (in particular, of Babylonian medical forecasting). The Stoic theory was not so much propositional logic as it was a technique of propositional logic for databases consisting of IF-THEN expert rules. In the Babylonian divination, each event has a (...) positive or negative value and all events are connected to each other. The Stoics also developed this idea and proposed a special modal logic in which logical determinism is considered an axiom. The paper reconstructs the sign-inference of the Stoics, as well as their modal logic. In particular, two Stoic squares of oppositions are proposed (for signs and for modal operators), which differ markedly from Aristotle’s square. (shrink)

The transition in Kant's writings form a pre-critical to a critical standpoint has been thoroughly documented with regard to Kant's changing conception of metaphysics, theory of knowledge, and philosophy of mathematics. But a similar alteration in standpoint in Kant's philosophy of logic has received little or no attention. This paper documents the existence of this shift in Kant's philosophy of logic and examines its nature. The resulting analysis provides evidence for the thesis that Kant began with a strictly intensional term (...) logic and with a theory of inference based on the analytic composition of concepts, and ended with a view of logic which, while remaining fundamentally intensional and term-based, shows movement towards a logic of propositions and propositional connectives. (shrink)

This paper seeks to elucidate the distinctive nature of the rational impression on its own terms, asking precisely what it means for the Stoics to define logikē phantasia as an impression whose content is expressible in language. I argue first that impression, generically, is direct and reflexive awareness of the world, the way animals get information about their surroundings. Then, that the rational impression, specifically, is inherently conceptual, inferential, and linguistic, i.e. thick with propositional content, the way humans receive (...) incoming information from the world. When we suspend certain contemporary assumptions about propositional content, the textual evidence can be taken at face value to reveal why, for the Stoics, rational impressions are called thoughts (noēseis) and how the Stoics’ novel semantic entities called lekta (roughly, the meanings of our words) depend on rational impressions for their subsistence. (shrink)

The theory of mental models is a current cognitive approach trying to describe the way people make inferences. According to this theory, people reason from possibilities or models linked to sentences. Sometimes, such possibilities or models are transformed by the action of a semantic modulation. The point this paper is intended to make is that Stoic logic also has the machinery to explain semantic processes such as that of modulation. This is shown by means of the criterion Chrysippus of (...) Soli provided for conditional sentences and the theory of sign related to that criterion. (shrink)

ABSTRACT: Alexander of Aphrodisias’ commentaries on Aristotle’s Organon are valuable sources for both Stoic and early Peripatetic logic, and have often been used as such – in particular for early Peripatetic hypothetical syllogistic and Stoic propositional logic. By contrast, this paper explores the role Alexander himself played in the development and transmission of those theories. There are three areas in particular where he seems to have made a difference: First, he drew a connection between certain passages from (...) Aristotle’s Topics and Prior Analytics and the Stoic indemonstrable arguments, and, based on this connection, appropriated at least four kinds of Stoic indemonstrables as Aristotelian. Second, he developed and made use of a specifically Peripatetic terminology in which to describe and discuss those arguments – which facilitated the integration of the indemonstrables into Peripatetic logic. Third, he made some progress towards a solution to the problem of what place and interpretation the Stoic third indemonstrables should be given in a Peripatetic and Platonist setting. Overall, the picture emerges that Alexander persistently (if not always consistently) presented passages from Aristotle’s logical œuvre in a light that makes it appear as if Aristotle was in the possession of a Peripatetic correlate to the Stoic theory of indemonstrables. (shrink)

This Article doDespite obvious differences in the Aristotelian and Stoic theories of responsibility, there is surprisingly a deeper structural similarity between the two. The most obvious difference is that Aristotle is (apparently) a libertarian and the Stoics are determinists. Aristotle holds adults responsible for all our "voluntary" actions, which are defined by two criteria: the "origin" or cause of the action must be "in us" and we must be aware of what we are doing. An "involuntary" action, for which (...) we are not responsible, is one that fails to meet either one of these two criteria. Aristotle is a libertarian insofar as he insists that all voluntary actions are "in our power" to perform or not. As determinists the Stoics cannot admit this sort of freedom, but they still consider the agent to be a vital link in the chain of events, so they redefine what is "in our power" as what comes about "through us." The terminology is different, but I argue that these actions, for which the Stoics hold us responsible, are in fact coextensive with Aristotle's voluntary actions. An "impression" is the first necessary condition for action, and is a sort of visual image of the object stimulating one to act. The right sort of impression activates the agent's "impulse," an internal movement of soul or mind, which is the direct cause of action. But impulse is always accompanied by "assent," which is the mind's affirming the truth of the proposition that we ought to go after the object stimulating our impulse. Thus, since assent is a necessary condition for action, we always act knowing what we are doing. This means that all actions caused by our own impulse and assent are by Aristotle's criteria voluntary, where impulse provides the internal origin of the action and assent provides the awareness of what is being done. I conclude that the Stoic and Aristotelian classes of what one is responsible for are coextensive, their criteria defining responsible actions are nearly identical, and the only substantial difference is that Aristotle claims such actions are in our power to do or not do while the Stoics say that such actions are necessitated (by our internal nature as well as external factors). es not have an abstract. (shrink)

ABSTRACT: This paper discusses the Stoic treatment of fallacies that are based on lexical ambiguities. It provides a detailed analysis of the relevant passages, lays bare textual and interpretative difficulties, explores what the Stoic view on the matter implies for their theory of language, and compares their view with Aristotle’s. In the paper I aim to show that, for the Stoics, fallacies of ambiguity are complexes of propositions and sentences and thus straddle the realms of meaning (which is (...) the domain of logic) and of linguistic expressions (which is the domain of linguistics), but also involve a pragmatic element; that the Stoics believe that the premises of the fallacies, when uttered, have only one meaning and are true, and thus should be conceded; that hence there is no need for a mental process of disambiguation in the listeners; that Aristotle, by contrast, appears to assume that the premises always have all their meanings, and accordingly recommends that the listeners explicitly disambiguate them, which presupposes a process of mental disambiguation. I proffer two readings of the Stoic advice that we ‘be silent’ when confronted with a fallacy of ambiguity in dialectical discourse, and explicate how each leads to an overall consistent interpretation of the textual evidence. Finally, I demonstrate that the method advocated by the Stoics works in all cases of fallacies of lexical ambiguity. (shrink)

Meijer's book, a comprehensive study of Stoic theological arguments, defends the thesis that the Stoics were not narrowly interested in proving the existence of a god. The theology of the Stoa began with its founder, Zeno of Citium, presenting arguments that the cosmos is an intelligent being, though Zeno himself seems not to have explicitly identified that intelligent being as god. A clear statement equating the cosmos with god had to wait until the rise of the third head of (...) the school, Chrysippus, though Meijer acknowledges that there is no reason to think that Zeno or Cleanthes, the second head, would have opposed the proposition that the cosmos, or at least the rational fire that pervades it, is god. Confusion about the true intent of Zeno's arguments is due to their distortion in the sources, for example, by Sextus Empiricus, who, Meijer contends, presents several of Zeno's arguments for the rationality of the cosmos as if they were intended as arguments to establish the existence of god. As a result, Sextus is an unreliable witness for determining the point of these arguments. Further confusing matters is the existence of a set of arguments attributed to Zeno that aim to establish the existence of the traditional gods. Meijer. (shrink)

Shows how Deleuze’s engagement with Stoicism produced many of his most singular and powerful ideas -/- Reveals a lasting influence on Gilles Deleuze by mapping his provocative reading of ancient Stoicism Unearths new possibilities for bridging contemporary philosophy and classics by engaging a vital yet recently rising area of scholarship: continental philosophy’s relationship to ancient philosophy Introduces the untranslated Stoic scholarship published by pre- and post-Deleuzian French philosophers of antiquity to the English-reading world -/- Deleuze dramatises the story of (...) ancient philosophy as a rivalry of four types of thinkers: the subverting pre-Socratics, the ascending Plato, the interiorising Aristotle and the perverting Stoics. Deleuze assigns the Stoics a privileged place because they introduced a new orientation for thinking and living that turns the whole story of philosophy inside out. -/- Ryan J. Johnson reveals Deleuze’s provocative reading of ancient Stoicism produced many of his most singular and powerful ideas. For Deleuze, the Stoics were innovators of an entire system of philosophy which they structured like an egg. Johnson structures his book in this way: Part I looks at physics (the yolk), Part II is logic (the shell) and Part III covers ethics (the albumen). Including previously untranslated French Stoic scholarship, Johnson unearths new possibilities for bridging contemporary and ancient philosophy. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Reviewed by:Introduction to Philosophical HermeneuticsLeon SuretteIntroduction to Philosophical Hermeneutics, by Jean Grondin; foreword by Hans-Georg Gadamer, trans. Joel Weinsheimer; xv & 231 pp. New Haven: Yale University Press, 1995, $25.00.Introduction to Philosophical Hermeneutics, a commissioned study for the Yale Studies in Hermeneutics, provides a comprehensive historical survey of interpretive theory from antiquity to the present. In addition it has a sixty-page bibliography subdivided into no fewer than thirty categories. (...) Unfortunately, the translator, Joel Weinsheimer (himself the translator of Gadamer and general editor of the series) has not added English translations to the bibliography, though he does cite from English translations. The index is inadequate—especially for a quasi-textbook.Grondin sets out to revise and correct the standard view of the development of philosophical hermeneutics: that it began with the formulation of fragmentary hermeneutic rules in the classical and patristic period, was refined with the systematic hermeneutics of Protestant theologians, then broadened into a universal methodology of the human sciences by Schleiermacher and Dilthey, culminating in Hans Georg Gadamer’s philosophical hermeneutics, which extended its reach into a critique of ideology, theory of science, and practical philosophy (p. 3).In place of this story, Grondin presents a single aperçu, “the ancient and perhaps antiquated doctrine of the verbum interius: the ‘inner word’ that is never spoken but nevertheless resounds in everything that is said,” and which he traces to the Stoics via St. Augustine (p. 119). Grondin reveals in his preface that he learned of the centrality of the inner word from Gadamer himself in a Heidelberg pub in the fall of 1988 while he was working on this book (pp. xiii–xiv). Gadamer told him that the claim to universality of philosophical hermeneutics is founded on the recognition of the primordiality of the inner word, to which the uttered word must strive to be adequate (pp. xiv and 123). This interior meaning can never be fully grasped, but it nonetheless provides a prophylactic against relativism. As Grondin puts it in a happy phrase, “original meaning... remains at best the asymptote of understanding, the telos that the interpreter is trying to reach behind the words” (p. 127). In this way philosophical hermeneutics turns philosophy away from epistemology—the concern with the outside, that to which language points, its propositional content—toward hermeneutics—the concern with that from which language emerges, “the conversation of the soul with itself” (p. 139), and the question (p. 119). If Grondin’s account is accepted, Richard Rorty is explicitly renouncing Gadamer when he asserts in Contingency, Irony, and Solidarity (p. 21) that “it is essential to my view that we have no pre-linguistic consciousness to which language needs to be adequate.”The historical survey is broken down into seven chapters: the first four cover [End Page 249] Classical, Patristic, Protestant, Romantic, and Historicist hermeneutics. Heidegger, Gadamer have one each, while Betti, Habermas, and Derrida are discussed in the last chapter. The historical survey is subdivided into authors too numerous to list. Grondin’s explication is uniformly clear and cogent; both novices and experts will find material for thought in his story.Grondin might be faulted for ignoring the Dutch, Italian, and English humanists, and for leaving Paul Ricoeur largely out of account. The only post-Medieval non-Germans to receive extended consideration are Emilio Betti and Jacques Derrida; the former because his hermeneutic theory precedes Gadamer’s by a few years, and the latter because he is a Heideggerean.Grondin sees deconstruction as “a regression into the propositional logic of metaphysics that dominated the entire West” because it is founded on a destructive critique of propositional logic—whereas Gadamerian philosophical hermeneutics is founded upon its replacement by the doctrine of the verbum interius (p. 138). Interestingly, he is also hostile to “historicism,” which—in contrast to Karl Popper—he sees as a positivistic effort to overcome the historicity of understanding (pp. 107–11).Leon SuretteUniversity of Western OntarioCopyright © 1996 The Johns Hopkins University Press... (shrink)

This paper aims to explain the distinction between syllogisms and subsyllogisms in Stoic logic. Subsyllogisms replace at least one premise in a syllogism with a premise that is, according to Galen and Alexander, equipollent to the respective syllogistic premise. This equipollence is not synonymy of meaning between two linguistic expressions, but obtains between two propositions when they are true or false by the same standard. Subsyllogistic premises are simple propositions that are equipollent to the non-simple premises of the respective (...) syllogisms. For subsyllogistic premises that replace syllogistic premises consist of predicates combining with cases rather than of connectives or negations governing propositions. Because of this difference in their premises, subsyllogisms have a different logical form than syllogisms and are not formally valid. (shrink)