This book traces the development of formal logic from its origins inancient Greece to the present day. The authors first discuss the work oflogicians from Aristotle to Frege, showing how they were influenced by thephilosophical or mathematical ideas of their time. They then examinedevelopments in the present century.

In the course of the discussion, Professor Quine pinpoints the difficulties involved in translation, brings to light the anomalies and conflicts implicit in our ...

Logical guarantees of validity must be understood as subject to the proviso that no equivocation is committed. But we do not have a formal theory of equivocation. This paper attempts to formulate rules for responding to equivocal arguments in the context of dialogue. What occurs when one distinguishes meanings of an equivocal expression turns out to be rather different from definition.

Finding a powerful ally in Bertrand Russell, who provided the foreword for this book, Gellner embarked on the project that was to put him on the intellectual ...

On 25th October 1946, in a crowded room in Cambridge, Ludwig Wittgenstein and Karl Popper came face to face for the first and only time. The meeting was a disaster, their loud and aggressive confrontation became the stuff of legend. This book tells what really went on in that room.

Both a Popper biography and an autobiography, Agassi's "A Philosopher's Apprentice" tells the riveting story of his intellectual formation in 1950s London, a young brilliant philosopher struggling with an intellectual giant - father, mentor, and rival, all at the same time. His subsequent rebellion and declaration of independence leads to a painful break, never to be completely healed. No other writer has Agassi's psychological insight into Popper, and no other book captures like this one the intellectual excitement around the Popper (...) circle in the 1950s and the struggles of the 1960s and 1970s - personal, academic, political, all important philosophically. Agassi's Popper - whether one agrees with it or not - is an enormous contribution to scholarship. This second revised edition includes also Popper's and Agassi's last correspondence and, in a postscript it shows Agassi leafing through Popper's archives, reaching a sort of reconciliation, an appropriate ending to the drama. A must read. Malachi Hacohen, Duke University. (shrink)

Equality1 gives rise to challenging questions which are not altogether easy to answer. Is it a relation? A relation between objects, or between names or signs of objects? In my Begriffsschrift I assumed the latter. The reasons which seem to favour this are the following: a = a and a = b are obviously statements of differing cognitive value; a = a holds a priori and, according to Kant, is to be labeled analytic, while statements of the form a = (...) b often contain very valuable extensions of our knowledge and cannot always be established a priori. The discovery that the rising sun is not new every morning, but always the same, was one of the most fertile astronomical discoveries. Even to-day the identification of a small planet or a comet is not always a matter of course. Now if we were to regard equality as a relation between that which the names ‘a’ and ‘b’ designate, it would seem that a = b could not differ from a = a (i.e. provided a = b is true). A relation would thereby be expressed of a thing to itself, and indeed one in which each thing stands to itself but to no other thing. What is intended to be said by a = b seems to be that the signs or names ‘a’ and ‘b’ designate the same thing, so that those signs themselves would be under discussion; a relation between them would be asserted. But this relation would hold between the names or signs only in so far as they named or designated something. It would be mediated by the connexion of each of the two signs with the same designated thing. But this is arbitrary. Nobody can be forbidden to use any arbitrarily producible event or object as a sign for something. In that case the sentence a = b would no longer refer to the subject matter, but only to its mode of designation; we would express no proper knowledge by its means. But in many cases this is just what we want to do. If the sign ‘a’ is distinguished from the sign ‘b’ only as object (here, by means of its shape), not as sign (i.e. not by the manner in which it designates something), the cognitive value of a = a becomes essentially equal to that of a = b, provided a = b is true.. (shrink)

This book presents novel formalizations of three of the most important medieval logical theories: supposition, consequence and obligations. In an additional fourth part, an in-depth analysis of the concept of formalization is presented - a crucial concept in the current logical panorama, which as such receives surprisingly little attention.Although formalizations of medieval logical theories have been proposed earlier in the literature, the formalizations presented here are all based on innovative vantage points: supposition theories as algorithmic hermeneutics, theories of consequence analyzed (...) with tools borrowed from model-theory and two-dimensional semantics, and obligations as logical games. For this reason, this is perhaps the first time that these medieval logical theories are made fully accessible to the modern philosopher and logician who wishes to obtain a better grasp of them, but who has always been held back by the lack of appropriate ‘translations' into modern terms.Moreover, the book offers a reflection on the very nature of logic, a reflection that is prompted by the comparisons between medieval and modern logic, their similarities and dissimilarities. It is thus a contribution not only to the history of logic, but also to the philosophy of logic, the philosophy of language and semantics.The analysis of medieval logic is also relevant for the modern philosopher and logician in that, being the unifying methodology used across all disciplines at that time, logic really provided unity to science. It thus presents a unified model of scientific investigation, where logic plays the aggregating role. (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 ...

Ernest Gellner (1925-1995) was one of the major thinkers of the 20th century. He held major chairs in philosophy, sociology and social anthropology during his distinguished career and contributed to a wide range of political and philosophical debates, most notably in linguistic philosophy, the theory of political nationalism and the theory of history. Gellner was also an outspoken defender of the Enlightenment tradition and social democracy.

Frege argued that though it is logically possible for an illogical community to exist, It is not possible that it should be right. Neither the assertion of false statements nor the acceptance of invalid arguments suffices to render a community illogical. The kinds of behavior which would suffice prove, On examination, To be very rare, But to justify frege's rather obscure remarks on illogicality and the universality of logical laws. The laws of logic are to be understood as constraints on (...) the kinds of rules governing linguistic exchanges needed if the language is to accommodate attempts to prove. (edited). (shrink)