Aristotle's explanation of what is said ‘of every’ and ‘of none’ has been interpreted either as involving individuals, or as regarding exclusively universal terms. I claim that Alexander of Aphrodisias endorsed this latter interpretation of the dictum de omni et de nullo. This interpretation affects our understanding of Alexander's syllogistic: as a matter of fact, Alexander maintained that the dictum de omni et de nullo is one of the core principles of syllogistic.

One may formulate the dependent product types of Martin-Löf type theory either in terms of abstraction and application operators like those for the lambda-calculus; or in terms of introduction and elimination rules like those for the other constructors of type theory. It is known that the latter rules are at least as strong as the former: we show that they are in fact strictly stronger. We also show, in the presence of the identity types, that the elimination rule for dependent (...) products–which is a “higher-order” inference rule in the sense of Schroeder-Heister–can be reformulated in a first-order manner. Finally, we consider the principle of function extensionality in type theory, which asserts that two elements of a dependent product type which are pointwise propositionally equal, are themselves propositionally equal. We demonstrate that the usual formulation of this principle fails to verify a number of very natural propositional equalities; and suggest an alternative formulation which rectifies this deficiency. (shrink)

The introduction of Greek philosophy into the Muslim world left an indelible mark on Islamic intellectual history. Philosophical discourse became a constant element in even traditionalist Islamic sciences. However, Aristotelian metaphysics gave rise to doctrines about God and the universe that were found highly objectionable by a number of Muslim theologians, among whom the fourteenth-century scholar Ibn Taymiyya stood foremost. Ibn Taymiyya, one of the greatest and most prolific thinkers in medieval Islam, held Greek logic responsible for the `heretical' metaphysical (...) conclusions reached by Islamic philosophers, theologians, mystics, and others. He therefore set out to refute philosophical logic, a task which culminated in one of the most devastating attacks ever levelled against the logical system upheld by the early Greeks, the later commentators, and their Muslim followers. His argument is grounded in an empirical approach that in many respects prefigures the philosophies of the British empiricists. Professor Hallaq's translation, with a substantial introduction and extensive notes, makes this important work available to a wider audience for the first time. (shrink)

This highly acclaimed book is a major contribution to the philosophy of language as well as a systematic interpretation of Frege, indisputably the father of ...

I LOGIC IN PHILOSOPHY— PHILOSOPHY OF LOGIC i. On the relation of logic to philosophy I n this book, the consequences of certain logical insights for ...

This volume examines the notion of an analytic proof as a natural deduction, suggesting that the proof's value may be understood as its normal form--a concept with significant implications to proof-theoretic semantics.

The present volume is intended as an all-round introduction to constructivism. Here constructivism is to be understood in the wide sense, and covers in particular Brouwer's intuitionism, Bishop's constructivism and A.A. Markov's constructive recursive mathematics. The ending "-ism" has ideological overtones: "constructive mathematics is the (only) right mathematics"; we hasten, however, to declare that we do not subscribe to this ideology, and that we do not intend to present our material on such a basis.

In this study two strands of inferentialism are brought together: the philosophical doctrine of Brandom, according to which meanings are generally inferential roles, and the logical doctrine prioritizing proof-theory over model theory and approaching meaning in logical, especially proof-theoretical terms.

In recent years, several formalisms for program construction have appeared. One such formalism is the type theory developed by Per Martin-L f. Well suited as a theory for program construction, it makes possible the expression of both specifications and programs within the same formalism. Furthermore, the proof rules can be used to derive a correct program from a specification as well as to verify that a given program has a certain property. This book contains a thorough introduction to type theory, (...) with information on polymorphic sets, subsets, monomorphic sets, and a full set of helpful examples. (shrink)

In this paper, we provide a detailed critical review of current approaches to ecthesis in Aristotle’s Prior Analytics, with a view to motivate a new approach, which builds upon previous work by Marion & Rückert (2016) on the dictum de omni. This approach sets Aristotle’s work within the context of dialectic and uses Lorenzen’s dialogical logic, hereby reframed with use of Martin-Löf's constructive type theory as ‘immanent reasoning’. We then provide rules of syllogistic for the latter, and provide proofs of (...) e-conversion, Darapti and Bocardo and e-subalternation, while showing how close to Aristotle’s text these proofs remain. (shrink)

The Dialectical Forge identifies dialectical disputation as a primary formative dynamic in the evolution of pre-modern Islamic legal systems, promoting dialectic from relative obscurity to a more appropriate position at the forefront of Islamic legal studies. The author introduces and develops a dialectics-based analytical method for the study of pre-modern Islamic legal argumentation, examines parallels and divergences between Aristotelian dialectic and early juridical jadal-theory, and proposes a multi-component paradigm—the Dialectical Forge Model—to account for the power of jadal in shaping Islamic (...) law and legal theory.In addition to overviews of current evolutionary narratives for Islamic legal theory and dialectic, and expositions on key texts, this work shines an analytical light upon the considerably sophisticated “proto-system” of juridical dialectical teaching and practice evident in Islam’s second century, several generations before the first “full-system” treatises of legal and dialectical theory were composed. This proto-system is revealed from analyses of dialectical sequences in the 2nd/8th century Kitāb Ikhtilāf al-ʿIrāqiyyīn / ʿIrāqiyyayn through a lens molded from 5th/11th century jadal-theory treatises. Specific features thus uncovered inform the elaboration of a Dialectical Forge Model, whose more general components and functions are explored in closing chapters. (shrink)

On the basis of Martin-Löf’s meaning explanations for his type theory a detailed justification is offered of the rule of identity elimination. Brief discussions are thereafter offered of how the univalence axiom fares with respect to these meaning explanations and of some recent work on identity in type theory by Ladyman and Presnell.

In these seven essays published from 1986 to 2008, philosophy is portrayed as an activity in which one gives an account of the experiences that one has and transmits through acting and speaking. A dialogical principle is an essential element of this account: in the I-role," one acts and speaks, while in the you-role," one passively experiences and understands. Only through learning from one another can the mutually dependent qualities of individuality and sociality gradually develop. ".

Few philosophers that have been studied as much as Ibn Sīnā have been as much misunderstood. His extraordinary ability to reflect upon and write in a variety of styles about seemingly every topic in every domain has steered his thought from philosophy and theology to mysticism and esoterism. Instead of helping us to learn and understand better Ibn Sīnā than he has previously been understood, the recent surge of Avicennan studies only adds more confusion to the already complex social context (...) which he was living in. (shrink)

Being a pragmatic and not a referential approach tosemantics, the dialogical formulation ofparaconsistency allows the following semantic idea tobe expressed within a semi-formal system: In anargumentation it sometimes makes sense to distinguishbetween the contradiction of one of the argumentationpartners with himself (internal contradiction) and thecontradiction between the partners (externalcontradiction). The idea is that externalcontradiction may involve different semantic contextsin which, say A and ¬A have been asserted.The dialogical approach suggests a way of studying thedynamic process of contradictions through which thetwo (...) contexts evolve for the sake of argumentation intoone system containing both contexts.More technically, we show a new, dialogical, way tobuild paraconsistent systems for propositional andfirst-order logic with classical and intuitionisticfeatures (i.e. paraconsistency both with and withouttertium non-datur) and present theircorresponding tableaux. (shrink)

This monograph proposes a new way of implementing interaction in logic. It also provides an elementary introduction to Constructive Type Theory. The authors equally emphasize basic ideas and finer technical details. In addition, many worked out exercises and examples will help readers to better understand the concepts under discussion. One of the chief ideas animating this study is that the dialogical understanding of definitional equality and its execution provide both a simple and a direct way of implementing the CTT approach (...) within a game-theoretical conception of meaning. In addition, the importance of the play level over the strategy level is stressed, binding together the matter of execution with that of equality and the finitary perspective on games constituting meaning. According to this perspective the emergence of concepts are not only games of giving and asking for reasons, they are also games that include moves establishing how it is that the reasons brought forward accomplish their explicative task. Thus, immanent reasoning games are dialogical games of Why and How. (shrink)

IF WITI'GENSTEIN COULD TALK, COULD WE UNDERSTAND HIM? Perusing the secondary literature on Wittgenstein, I have frequently experienced a perfect Brechtean Entfremdungseffekt. This is interesting, I have felt like saying when reading books and papers on Wittgenstein, but who is the writer talking about? Certainly not Ludwig Wittgenstein the actual person who wrote his books and notebooks and whom I happened to meet. Why is there this strange gap between the ideas of the actual philosopher and the musings of his (...) interpreters? Wittgenstein is talking to us through the posthumous publication of his writings. Why don't philosophers understand what he is saying? A partial reason is outlined in the first essay of this volume. Wittgenstein was far too impatient to explain in his books and book drafts what his problems were, what it was that he was trying to get clear about. He was even too impatient to explain in full his earlier solutions, often merely referring to them casually as it were in a shorthand notation. For one important instance, in The Brown Book, Wittgenstein had explained in some detail what name-object relationships amount to in his view. There he offers both an explanation of what his problem is and an account of his own view illustrated by means of specific examples of language-games. But when he raises the same question again in Philosophical Investigations I, sec. (shrink)

Terence Parsons presents a new study of the development and continuing value of medieval logic, which expanded Aristotle's basic principles of logic in important ways. Parsons argues that the resulting system is as rich as contemporary first-order symbolic logic.

Prolegomena It is fitting to begin this book on intuitionistic type theory by putting the subject matter into perspective. The purpose of this chapter is to ...

This is a study of dialectic and systematic disputation as described in the theoretical writings of Islamic theologians, jurists, and philosophers. An attempt is made to reconstruct the contents of the earliest systematic treatment of the subject by b. al-Riwandi. The theological understanding of dialectic is then contrasted with the teachings of the Arab Aristotelians--al-Farabi, Avicenna, and Averroes, on dialectic. It is then shown how jurists took over the theological method of dialectic and applied it to problems peculiar to jurisprudence. (...) Although the earliest writings on dialectic are fairly free of direct Aristotelian influence, there are coincidences of themes and treatment. But after jurisprudence had assimilated the techniques of theological dialectic, its own theory became increasingly influenced by logical terminology and techniques. ;At the end of the thirteenth century there arose a new discipline, the adab al-bahth, that considered the general rules of disputation per se. It was thus shown to be applicable to disputations on theology, jurisprudence, and philosophy. In form and substance, the adab al-bahth is comparable to modern theories of argument and disputation. The roles of proponent and respondent are sharply defined and a proof that all debate must be finite is brought forward. While the theoretical underpinnings of the new system are Aristotelian, the terminology and order of debate place it firmly in the Islamic tradition of disputation. (shrink)

This chapter tells how, within a century, the notions of judgment and inference were driven out of logical theory and replaced by propositions and consequence. Systematic considerations guide the treatment. The history is unashamedly Whiggish: the current position is shown as the outcome, or even culmination, of a historical development.

Many of the discussions about conditionals can best be put as follows:can those conditionals that involve an entailment relation be formulatedwithin a formal system? The reasons for the failure of the classical approachto entailment have usually been that they ignore the meaning connectionbetween antecedent and consequent in a valid entailment. One of the firsttheories in the history of logic about meaning connection resulted from thestoic discussions on tightening the relation between the If- and the Then-parts of conditionals, which in this (...) context was called. This theory gave a justification for the validity of what we todayexpress through the formulae ¬ and ¬. Hugh MacColl and, more recently, Storrs McCall searched for a formal system in which the validity ofthese formulae could be expressed. Unfortunately neither of the resulting systems is very satisfactory. In this paper we introduce dialogical games with the help of a new connexive If-Then (), the structural rules of which allow the Proponent to develop winning strategies not only for the above-mentioned connexive theses but also for ¬ and ¬. Further on, we developthe corresponding tableau systems and conclude with some remarks on possibleperspectives and consequences of the dialogical approach to connexivity including the loss of uniform substitution leading to a new concept of logical form. (shrink)

Section 1 contains a survey of options in constructing a formal system of dialogue rules. The distinction between material and formal systems is discussed (section 1.1). It is stressed that the material systems are, in several senses, formal as well. In section 1.2 variants as to language form (choices of logical constants and logical rules) are pointed out. Section 1.3 is concerned with options as to initial positions and the permissibility of attacks on elementary statements. The problem of ending a (...) dialogue, and of infinite dialogues, is treated in section 1.4. Other options, e.g., as to the number of attacks allowed with respect to each statement, are listed in section 1.5. Section 1.6 explains the concept of a chain of arguments.From section 2 onward four types of dialectic systems are picked out for closer study: D, E, Di and Ei. After a preliminary section on dialogue sequents and winning strategies, the equivalence of derivability in intuitionistic logic and the existence of a winning strategy (for the Proponent) on the strength of Ei is shown by simple inductive proofs. (shrink)

The framework of natural deduction is extended by permitting rules as assumptions which may be discharged in the course of a derivation. this leads to the concept of rules of higher levels and to a general schema for introduction and elimination rules for arbitrary n-ary sentential operators. with respect to this schema, (functional) completeness "or", "if..then" and absurdity is proved.

The Arabic-Islamic tradition is founded on the following new epistemic attitude that reinvents knowledge: to learn from the contributions of previous civilisations through the systematic survey of all extant scientific works; to contribute to the further development of knowledge by linking it, through usefulness, to practice and the practical need of society; to facilitate its learning for younger generations and its transmission to future civilizations since it is conceived not as a finished product but as an ongoing process. The worldwide (...) development of the reinvented knowledge has led to its universalisation and the rapid expansion of mathematics has particularly and led to the complete de-hellinisation of the Greek conception of science and philosophy. (shrink)

Even when inconsistencies are present in our premise set, we can sensibly distinguish between good and bad arguments relying on these premises. In making this distinction, the inconsistency-adaptive approach of Batens strikes a particularly nice balance between inconsistency-tolerance and inferential strength. In this paper, we use the machinery of Batens’ approach to extend the paraconsistent approach to dialogical logic as developed by Rahman and Carnielli. In bringing these frameworks closer together, we obtain a dynamic mechanism for the systematic study of (...) dialogues in which two parties exchange arguments over a central claim, in the possible presence of inconsistencies. (shrink)

This completely self-contained study, widely considered the best book in the field, is intended to serve both as an introduction to quantification theory and as ...

In this new book, John McDowell builds on his much discussed Mind and World—one of the most highly regarded books in contemporary philosophy.

Without violating the spirit of Game-Theoretical semantics, its results can be re-worked in Martin-Löf''s Constructive Type Theory by interpreting games as types of Myself''s winning strategies. The philosophical ideas behind Game-Theoretical Semantics in fact highly recommend restricting strategies to effective ones, which is the only controversial step in our interpretation. What is gained, then, is a direct connection between linguistic semantics and computer programming.