Avicenna refers on a number of occasions in his Book of the Syllogism to “the eminent later scholar” . At least three recent studies have argued or assumed that this eminent later scholar is Alexander of Aphrodisias. It is argued in this article that Avicenna is in fact referring to Alfarabi. This has consequences for reconstructing the lost first part of Alfarabi's Great Commentary on the Prior Analytics , for highlighting certain aspects of Alfarabi's logical doctrines, and for understanding more (...) about the relation between Avicenna and Alfarabi in matters logical. (shrink)

Al-Fbb al-f, is apparently the first person to maintain that existence, in one of its senses, is a second-order concept [mal th]. As he interprets Metaphysics d] has two meanings, second-order being as truth'' (including existence as well as propositional truth), and first-order being as divided into the categories.'' The paronymous form of the Arabic word mawjd] distinct from their essences: for al-Kindd of all things. Against this, al-Fburr thinks that Greek more appropriately expressed many such concepts, including being, by (...) particles rather than nouns or verbs; he takes Metaphysics r's title can mean both Book of Particles'' and Aristotle's Metaphysics.''. (shrink)

Boethius' treatise De Hypotheticis Syllogismis provided twelfth-century philosophers with an introduction to the logic of conditional and disjunctive sentences but this work is the only part of the logica vetus which is no longer studied in the twelfth century. In this paper I investigate why interest in Boethius acount of hypothetical syllogisms fell off so quickly. I argue that Boethius' account of compound sentences is not an account of propositions and once a proper notion of propositionality is available the argument (...) forms accepted by Boethius are seen to be incoherent. It was Peter Abaelard who first understood the nature of propositionality and propositional connectives and used this to criticise Boethius' claims in De Hypothetics Syllogismis. In place Boethius' confusion Abaelard offered a simple and correct account of the hypothetical syllogism. (shrink)

In a departure from the tradition of the Neoplatonic commentators of the Organon, the sequence of summaries in the insert two treatises between the Prior Analytics and the Posterior Analytics, namely the Resolution and the Sophistical Refutations. And even though the Tal30), while it. The contents of kitl and the different titles that the fahiktist), lead one to realize that it is an addition to the Prior Analytics offering a theory concerning the generation of the premisses of the syllogism, something (...) that may have appeared to Alfarabi as missing from Kits. (shrink)

This paper is obsolete. It is superseded by the book, Conditionals in Context, MIT Press, 2005.

In the present article we attempt to show that Aristotle's syllogistic is an underlying logiC which includes a natural deductive system and that it isn't an axiomatic theory as had previously been thought. We construct a mathematical model which reflects certain structural aspects of Aristotle's logic. We examine the relation of the model to the system of logic envisaged in scattered parts of Prior and Posterior Analytics. Our interpretation restores Aristotle's reputation as a logician of consummate imagination and skill. Several (...) attributions of shortcomings and logical errors to Aristotle are shown to be without merit. Aristotle's logic is found to be self-sufficient in several senses: his theory of deduction is logically sound in every detail. (His indirect deductions have been criticized, but incorrectly on our account.) Aristotle's logic presupposes no other logical concepts, not even those of propositional logic. The Aristotelian system is seen to be complete in the sense that every valid argument expressible in his system admits of a deduction within his deductive system: every semantically valid argument is deducible. (shrink)

The standard use of the propositional calculus ('P.C.?) in analyzing the validity of inferences involving conditionals leads to fallacies, and the problem is to determine where P.C. may be ?safely? used. An alternative analysis of criteria of reasonableness of inferences in terms of conditions of justification rather than truth of statements is proposed. It is argued, under certain restrictions, that P. C. may be safely used, except in inferences whose conclusions are conditionals whose antecedents are incompatible with the premises in (...) the sense that if the antecedent became known, some of the previously asserted premises would have to be withdrawn. (shrink)

The paper discusses al-Kindī's response to doctrines held by contemporary theologians of the Mu‘tazilite school: divine attributes, creation, and freedom. In the first section it is argued that, despite his broadly negative theology, al-Kindī recognizes a special kind of “essential” positive attribute belonging to God. The second section argues that al-Kindī agreed with the Mu‘tazila in holding that something may not yet exist but still be an object of God's knowledge and power. Also it presents a new parallel between al-Kindī (...) and John Philoponus. The third section gives an interpretation of al-Kindī as a compatibilist, in other words as holding that humans may be free even though their actions are necessitated. In all three cases, it is argued, al-Kindī is close to the Mu‘tazilite point of view, though he departs from them in the arguments he gives for that point of view. (shrink)