Positivists identify science and certainty and in the name of the utter rationality of science deny that it rests on speculative presuppositions. The Logical Positivists took a step further and tried to show such presuppositions really no presuppositions at all but rather poorly worded sentences. Rules of sentence formation, however, rest on the presuppositions about the nature of language. This makes us unable to determine the status of mathematics, which is these days particularly irksome since this question is now-since Abraham (...) Robinson-one that mathematicians cannot ignore. Since mathematics is the paradigm of a logical discourse, logic must offer a system adequate enough to serve mathematics. This fact makes it difficult to avoid making question-begging moves in both mathematics and logic. We must therefore view the rationality of logic as partial and hope it is stepwise improvable. The theory of rationality thus turns to be the major presupposition of logic, and one which has ample metaphysical background to it. The very supposition, basic to all logic, that language is divisible into form andcontent is under suspicion-mathematics perhaps belongs to neither. (shrink)

The present book is the English version of a monograph 'Die aristotelische Syllogistik', which first appeared ten years ago in the series of Abhand 1 lungen edited by the Academy of Sciences in Gottingen. In the preface to the English edition, I would first like to express my indebtedness to Mr. J. Barnes, now fellow of Oriel College, Oxford. He not only translated what must have been a difficult text with exemplary precision and ingenuity, but followed critically every argument and (...) check ed every reference. While translating it, he has improved the book. Of those changes which I have made on Mr. Barnes' suggestion I note only the more important ones on pages 4, 12, 24sq, 32, 39, 6lsq, and 158. Since the second edition of the German text appeared in 1963 some further reviews have been published, or come to my notice, which I have 2 been able to make use of in improving the text of this new edition. I must mention here especially the detailed critical discussions of my results and arguments published by Professor W. Wieland in the Philosophische Rundschau 14 (1966), 1-27 and by Professor E. Scheibe in Gnomon 39 (1967), 454-64. Both scholars, while agreeing with the main drift and method of my interpretation, criticise some of my results and disagree with some of my arguments. It would not be possible to discuss these technical matters here with the necessary thoroughness. (shrink)

Since the time of Aristotle's students, interpreters have considered Prior Analytics to be a treatise about deductive reasoning, more generally, about methods of determining the validity and invalidity of premise-conclusion arguments. People studied Prior Analytics in order to learn more about deductive reasoning and to improve their own reasoning skills. These interpreters understood Aristotle to be focusing on two epistemic processes: first, the process of establishing knowledge that a conclusion follows necessarily from a set of premises (that is, on the (...) epistemic process of extracting information implicit in explicitly given information) and, second, the process of establishing knowledge that a conclusion does not follow. Despite the overwhelming tendency to interpret the syllogistic as formal epistemology, it was not until the early 1970s that it occurred to anyone to think that Aristotle may have developed a theory of deductive reasoning with a well worked-out system of deductions comparable in rigor and precision with systems such as propositional logic or equational logic familiar from mathematical logic. When modern logicians in the 1920s and 1930s first turned their attention to the problem of understanding Aristotle's contribution to logic in modern terms, they were guided both by the Frege-Russell conception of logic as formal ontology and at the same time by a desire to protect Aristotle from possible charges of psychologism. They thought they saw Aristotle applying the informal axiomatic method to formal ontology, not as making the first steps into formal epistemology. They did not notice Aristotle's description of deductive reasoning. Ironically, the formal axiomatic method (in which one explicitly presents not merely the substantive axioms but also the deductive processes used to derive theorems from the axioms) is incipient in Aristotle's presentation. Partly in opposition to the axiomatic, ontically-oriented approach to Aristotle's logic and partly as a result of attempting to increase the degree of fit between interpretation and text, logicians in the 1970s working independently came to remarkably similar conclusions to the effect that Aristotle indeed had produced the first system of formal deductions. They concluded that Aristotle had analyzed the process of deduction and that his achievement included a semantically complete system of natural deductions including both direct and indirect deductions. Where the interpretations of the 1920s and 1930s attribute to Aristotle a system of propositions organized deductively, the interpretations of the 1970s attribute to Aristotle a system of deductions, or extended deductive discourses, organized epistemically. The logicians of the 1920s and 1930s take Aristotle to be deducing laws of logic from axiomatic origins; the logicians of the 1970s take Aristotle to be describing the process of deduction and in particular to be describing deductions themselves, both those deductions that are proofs based on axiomatic premises and those deductions that, though deductively cogent, do not establish the truth of the conclusion but only that the conclusion is implied by the premise-set. Thus, two very different and opposed interpretations had emerged, interestingly both products of modern logicians equipped with the theoretical apparatus of mathematical logic. The issue at stake between these two interpretations is the historical question of Aristotle's place in the history of logic and of his orientation in philosophy of logic. This paper affirms Aristotle's place as the founder of logic taken as formal epistemology, including the study of deductive reasoning. A by-product of this study of Aristotle's accomplishments in logic is a clarification of a distinction implicit in discourses among logicians--that between logic as formal ontology and logic as formal epistemology. (shrink)

JOSEPH AGASSI 1. Sir Karl Popper has offered two different theories of scientific progress, his theory of conjectures and refutations and corroboration, as well as his theory of verisimilitude increase. The former was attacked by some old-fashioned inductivists, yet is triumphant; the latter has been refuted by Tichy and by Miller to Popper’s own satisfaction. Oddly, however, the theory of verisimilitude was developed because of some deficiency in the theory of corroboration, and though in its present precise formulation it was (...) refuted, Popper still holds it in general terms, and I think he still hopes to find a better precise formulation of it. My aims in the present note are to pin-point the deficiency of Popper’s theory of corroboration and to use this for a precise formulation of verisimilitude increase acceptable to him. For my part, however, I see the situation in a different way, as will be indicated at the end of this note. (shrink)

The last phase of Greek philosophy has until recently been less intelligently studied than any other, and in our understanding of its development there are still lamentable lacunae. Three errors in particular have in the past prevented a proper appreciation of Plotinus' place in the history of philosophy. The first was the failure to distinguish Neoplatonism from Platonism: this vitiates the work of many early exponents from Ficinus down to Kirchner. The second was the belief that the Neoplatonists, being ‘mystics,’ (...) were necessarily incomprehensible to the plain man or even to the plain philosopher. To have encouraged the persistence of this superstition in the nineteenth century is the least pardonable of Creuzer's many sins. The third was the chronological confusion involved in the ascription to Saint Paul's contemporary of the works of the pretended Dionysius Areopagita, which contain a fully-developed Neoplatonic theology. Though the fraud had been exposed by Scaliger, these writings continued down to the beginning of the nineteenth century to be used as evidence that the ‘Nsoplatonic trinity’ was an inferior imitation of the Christian one. When this false trail was at length abandoned the fashion for orientalizing explanations persisted in another guise: to the earliest historians of Neoplatonism, Simon and Vacherot, the school of Plotinus was ‘the school of Alexandria,’ and its inspiration was mainly Egyptian. Vacherot says of Neoplatonism that it is ‘essentially and radically oriental, having nothing of Greek thought but its language and procedure.’ Few would be found to-day to subscribe to so sweeping a pronouncement; but the existence of an important oriental element in Plotinus' thought is still affirmed by many French and German writers. (shrink)

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