This open access book is a superb collection of some fifteen chapters inspired by Schroeder-Heister's groundbreaking work, written by leading experts in the field, plus an extensive autobiography and comments on the various contributions by Schroeder-Heister himself. For several decades, Peter Schroeder-Heister has been a central figure in proof-theoretic semantics, a field of study situated at the interface of logic, theoretical computer science, natural-language semantics, and the philosophy of language. -/- The chapters of which this book is composed discuss the (...) subject from a rich variety of angles, including the history of logic, the proper interpretation of logical validity, natural deduction rules, the notions of harmony and of synonymy, the structure of proofs, the logical status of equality, intentional phenomena, and the proof theory of second-order arithmetic. All chapters relate directly to questions that have driven Schroeder-Heister's own research agenda and to which he has made seminal contributions. The extensive autobiographical chapter not only provides a fascinating overview of Schroeder-Heister's career and the evolution of his academic interests but also constitutes a contribution to the recent history of logic in its own right, painting an intriguing picture of the philosophical, logical, and mathematical institutional landscape in Germany and elsewhere since the early 1970s. The papers collected in this book are illuminatingly put into a unified perspective by Schroeder-Heister's comments at the end of the book. Both graduate students and established researchers in the field will find this book an excellent resource for future work in proof-theoretic semantics and related areas. (shrink)

A running commentary is offered on the first half of Frege’s Grundlagen der Arithmetik, §17, and suggests that Frege anticipated the method of demonstration used by Paul Bernays for the Deduction Theorem.

Logicism is, roughly speaking, the doctrine that mathematics is fancy logic. So getting clear about the nature of logic is a necessary step in an assessment of logicism. Logic is the study of logical concepts, how they are expressed in languages, their semantic values, and the relationships between these things and the rest of our concepts, linguistic expressions, and their semantic values. A logical concept is what can be expressed by a logical constant in a language. So the question “What (...) is logic?” drives us to the question “What is a logical constant?” Though what follows contains some argument, limitations of space constrain me in large part to express my Credo on this topic with the broad brush of bold assertion and some promissory gestures. (shrink)

This short book comprises “four largely self-contained studies … unified by a common interpretive approach”, the “investigation of the historical development of … Wittgenstein’s early philosophy”. Proops applies this historical approach to Wittgenstein’s conception of logic, his critique of “logical assertion,” his “picture theory” of language, and his discussion of the justification of deduction. He endeavors to “bring out how Wittgenstein develops his views … as foils to the positions developed by Frege and Russell”, arguing that “it is not Frege (...) but Russell whose work provides the most important background for … the Tractatus”. (shrink)

Wittgenstein gives voice to an aspiration that is central to his later philosophy, well before he becomes later Wittgenstein, when he writes in §4.112 of the Tractatus that philosophy is not a matter of putting forward a doctrine or a theory, but consists rather in the practice of an activity – an activity he goes on to characterize as one of elucidation or clarification – an activity which he says does not result in philosophische Sätze, in propositions of philosophy, but (...) rather in das Klarwerden von Sätzen, in our attaining clarity in our relation to the sentences of our language that we call upon to express our thoughts.1 To say that early Wittgenstein already aspired to such a conception of philosophy is not to gainsay that to aspire to practice philosophy in such a manner and to succeed in doing so are not the same thing. It is therefore not to deny that, by Wittgenstein’s later lights, the Tractatus is to be judged a work that is marked by forms of failure tied to its having failed fully to live up to such an aspiration. But if it is thus to be judged, then it is to some degree a failure even by Wittgenstein’s own earlier lights. This means that if one wants to understand the fundamental turn in Wittgenstein’s thinking as he moves from his earlier to his later philosophy, and why it is that he wanted the Tractatus to be published and read together with Philosophical Investigations, one needs to understand what sort of failure this is – and that requires coming to terms with the Tractatus’s own understanding of what sort of work it was trying to be. We think that readers of the Tractatus – be they admirers or detractors of Wittgenstein – have, on the whole, failed to do this. (shrink)

This thesis discusses some central aspects of Wittgenstein's conception of language and logic in his Tractatus Logico-Philosophicus and brings them into relation with the philosophies of Frege and Russell. The main contention is that a fruitful way of understanding the Tractatus is to see it as responding to tensions in Frege's conception of logic and Russell's theory of judgement. In the thesis the philosophy of the Tractatus is presented as developing from these two strands of criticism and thus as the (...) culmination of the philosophy of logic and language developed in the early analytic period. Part one examines relevant features of Frege's philosophy of logic. Besides shedding light on Frege's philosophy in its own right, it aims at preparing the ground for a discussion of those aspects of the Tractatus' conception of logic which derive from Wittgenstein's critical response to Frege. Part two first presents Russell's early view on truth and judgement, before considering several variants of the multiple relation theory of judgement, devised in opposition to it. Part three discusses the development of Wittgenstein's conception of language and logic, beginning with Wittgenstein's criticism of the multiple relation theory and his early theory of sense, seen as containing the seeds of the picture theory of propositions presented in the Tractatus. I then consider the relation between Wittgenstein's pictorial conception of language and his conception of logic, arguing that Wittgenstein's understanding of sense in terms of bipolarity grounds his view of logical complexity and of the essence of logic as a whole. This view, I show, is free from the internal tensions that affect Frege's understanding of the nature of logic. (shrink)