Jean-Yves Beziau

After telling the story of the world logic prizes contest and its origin, we explain the value of such a contest by examining what is a prize. We compare the idea of a _World Logic Prize_ with other prizes, awards, medals, highlighting the importance of logic, as the characteristic feature of human beings. We then explain how the contest is organized, pointing out the similar perspective to that of the _World Logic Day_, launched on January 14, 2019, about six months after the first edition of the World Logic Prizes Contest, June 24, 2018.

The difference between truth and logical truth is a fundamental distinction of modern logic promoted by Wittgenstein. We show here how this distinction leads to a metalogical triangle of contrariety which can be naturally extended into a metalogical hexagon of oppositions, representing in a direct and simple way the articulation of the six positions of a proposition vis-à-vis a theory. A particular case of this hexagon is a metalogical hexagon of propositions which can be interpreted in a modal way. We end by a semiotic hexagon emphasizing the value of true symbols, in particular the logic hexagon itself.

In this chapter, we explain why Ex contradictione sequitur quodlibet is a confusing expression to denote the statement p,¬p⊢q\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p, \neg p \vdash q$$\end{document}, and we also explain why this statement is ambiguous. We start by setting out a framework about consequence relation and truth. We proceed by presenting the basic concepts of the theory of opposition and the meaning of contradiction according to this theory. We then introduce the notion of incompatibility, and, on the basis of that, we deal with explosion and introduce the notion of compatible negation. The final part of the paper is about John Corcoran.

We discuss the evolution of the World Logic Prizes Contest. In a first section, we describe how this contest developed, on the on hand by the creation of the Universal Logic Prize starting in 2005 at the 1st World Congress and School on Universal Logic in Montreux, Switzerland, on the other hand by the creation of the Newton da Costa Logic Prize in Brazil in 2014. These two projects joined in 2018 by the organization of the 1st World Logic Prizes Contest at the 6th World Congress and School on Universal Logic in Vichy, France. In a second section, we talk about the organization of the 2nd World Logic Prizes Contest to take place in April 2022 at the 6th World Congress and School on Universal Logic in Crete, Greece. We explain that there will be 15 contestants from 15 different countries with a good geographic distribution. In a third section, we discuss how this project can develop in the future with the creation of more logic prizes, the creation of similar prizes in other fields and the organization of a World Scientific Prizes Contest.

John Corcoran was a very well-known logician who worked on several areas of logic. He produced decisive works giving a better understanding of two major figures in the history of logic, Aristotle and Boole. Corcoran had a close association with Alfred Tarski, a prominent 20th-century logician. This collaboration manifested in Corcoran's substantial introduction to Tarski's seminal book, Logic, Semantics, Metamathematics (1956). Additionally, Corcoran's posthumous editorial involvement in 'What are logical notions?' (1986) breathed new life into this seminal paper authored by Tarski. His scholarly pursuits extended to the intricate explication of fundamental concepts in modern logic, including variables, propositions, truth, consequences, and categoricity. Corcoran's academic curiosity extended further to the intersection of ethics and logic, reflecting his contemplation of their interrelation. Beyond these theoretical contributions, Corcoran was deeply engaged in the pedagogical dimensions of logic instruction.

Im Folgenden stellen wir drei aktuelle Forschungsbereiche zur formalen Logik bei Kant allgemeinverständlich dar und greifen dabei auf die trans zendentale Logik nur dann zurück, wenn sie ein besseres Verständnis der formalen Logik ermöglicht: Zunächst wird Kants Beitrag zur Rezeption und Weiterentwicklung von Euler-artigen Diagrammen dargestellt. Diese Diagramme wurden in den 1990er Jahren wiederentdeckt, als formales System interpretiert und werden heute insbes. in der Didaktik, in den Kognitionswissenschaften, in der Linguistik, in KI-Bereichen wie der (Logik-basierten) Wissensrepräsentation eingesetzt, und auch in der Philosophie verwendet (Kapitel 2). Mehrere Studien haben in den letzten Jahren gezeigt, dass Kant in weiten Teilen seines Systems Oppositionsverhältnisse verwendet, die der Struktur des logischen Quadrats entsprechen. Das logische Quadrat ist heute Gegenstand intensiver Forschung, da es neben der klassischen, auch die paravollständige und parakonsistente Negation abbildet (Kap. 3). Jüngst wurde zudem die Implementierbarkeit der kantischen Logik in ein formalisiertes deduktives System bewiesen. Die Bedeutung dieses Ergebnisses wird insbesondere im Hinblick auf die formalisierte Umsetzung der Sätze vom Widerspruch, vom zureichenden Grund und der Ausschließung des Mittleren erläutert (Kap. 4). Abschließend möchten wir ein paar Perspektiven für die Forschung zur formalen Logik bei Kant nennen (Kap. 5). -- Note: No financial support acknowledged by the second autor (S. Kovač).

Universal Logic is not a new logic, but a general theory of logics, considered as mathematical structures. The name was introduced about ten years ago, but the subject is as old as the beginning of modern logic: Alfred Tarski and other Polish logicians such as Adolf Lindenbaum developed a general theory of logics at the end of the 1920s based on consequence operations and logical matrices. The subject was revived after the flowering of thousands of new logics during the last thirty years: there was a need for a systematic theory of logics to put some order in this chaotic multiplicity. This book contains recent works on universal logic by first-class researchers from all around the world. The book is full of new and challenging ideas that will guide the future of this exciting subject. It will be of interest for people who want to better understand what logic is. Tools and concepts are provided here for those who want to study classes of already existing logics or want to design and build new ones.

Universal logic is to logic what universal algebra is to algebra. It is not a specific system of logic that would apply to everything but a general theory of all existing and possible logics. This new field has been slowly emerging through the new directions of research in logic of the past decades and the name was coined 15 years ago. In the Spring of 2005 was organized in Montreux, Switzerland, the First World Congress on Universal Logic. This exciting event gathered more than 200 people from about 40 different countries. Many famous logicians were present there, such as Dov Gabbay, Krister Segerberg, Saul Kripke, Michael Dunn, Jouko Väännänen. Most of the papers in this book arose from talks - and discussions that follow - presented during this event. They are concerned with philosophical and historical approaches discussing the basic concepts of logic and reflecting the meaning of a universal approach to logic, the development and elaboration of general tools in order to construct frameworks useful for studying classes of logics, applications of logics to concrete problems through the universal perspective.

In this paper we address some central problems of combination of logics through the study of a very simple but highly informative case, the combination of the logics of disjunction and conjunction. At first it seems that it would be very easy to combine such logics, but the following problem arises: if we combine these logics in a straightforward way, distributivity holds. On the other hand, distributivity does not arise if we use the usual notion of extension between consequence relations. A detailed discussion about this phenomenon, as well as some elucidation for it, is given.

After explaining the interdisciplinary aspect of the series of events organized around the square of opposition since 2007, we discuss papers related to the 4th World Congress on the Square of Opposition which was organized in the Vatican at the Pontifical Lateran University in 2014. We distinguish three categories of work: those dealing with the evolution and development of the theory of opposition, those using the square as a metalogical tool to give a better understanding of various systems of logic and those related with applications of the theory of opposition to conceptual analysis and pedagogy.

In this paper we discuss the recent developments of logic and explain what can be done to promote a bright future for logic. After comments on the contest The Future of Logic that took place during the 5th UNILOG in Istanbul in 2015, we give a general idea of how logic can be practiced and understood, emphasizing in particular the distinction between logic as reasoning and logic as the science of reasoning. And we discuss some projects we have launched: the book series Logic PhDs, series of events such as UNILOG, SQUARE and LIQ, the Logic Prizes Contest and the World Logic Day.