‘Logical Realism’ is taken to mean many different things. I argue that if reality has a privileged structure, then a view I call metaphysical logical realism is true. The view says that, first, there is ‘ One True Logic ’ ; second, that the One True Logic is made true by the mind ‐ and ‐ language ‐ independent world; and third, that the mind ‐ and ‐ language ‐ independent world makes it the case that the One True Logic is better than any other logic at capturing the structure of reality. Along the way, I discuss a few alternatives, and clarify two distinct kinds of metaphysical logical realism.
Dialogical Logic
This entry presents the framework of « dialogical logic » in the initial Lorenzen and Lorenz tradition. The rules for the game and for building strategies are provided with step by step examples, helping the reader understand how the dialogue tables reflect a dynamic process of interaction between the players. Various logics are presented within this pluralistic framework: intuitionist logic, classical logic, and modal logics, with references to various other logics. In a second part of the entry, objections against the framework are considered, together with answers provided by the « Immanent Reasoning » variant, which stays within the Lorenzen and Lorenz tradition, and by the « Built-In Opponent » variant first developed by Catarina Dutilh Novaes, which develops a different dialogical tradition.
Norms and Necessity
Philosophical theories often hinge on claims about what is necessary or possible. But what are possibilities and necessities, and how could we come to know about them? This book aims to help demystify the methodology of philosophy, by treating such claims not as attempted descriptions of strange facts or distant ‘possible worlds’, but rather as ways of expressing rules or norms.
Ezumezu: A System of Logic for African Philosophy and Studies
The issue of a logic foundation for African thought connects well with the question of method. Do we need new methods for African philosophy and studies? Or, are the methods of Western thought adequate for African intellectual space? These questions are not some of the easiest to answer because they lead straight to the question of whether or not a logic tradition from African intellectual space is possible. Thus in charting the course of future direction in African philosophy and studies, one must be confronted with this question of logic. The author boldly takes up this challenge and becomes the first to do so in a book by introducing new concepts and formulating a new African culture-inspired system of logic called Ezumezu which he believes would ground new methods in African philosophy and studies. He develops this system to rescue African philosophy and, by extension, sundry fields in African Indigenous Knowledge Systems from the spell of Plato and the hegemony of Aristotle. African philosophers can now ground their discourses in Ezumezu logic which will distinguish their philosophy as a tradition in its own right. On the whole, the book engages with some of the lingering controversies in the idea of (an) African logic before unveiling Ezumezu as a philosophy of logic, methodology and formal system. The book also provides fresh arguments and insights on the themes of decolonisation and Africanisation for the intellectual transformation of scholarship in Africa. It will appeal to philosophers and logicians—undergraduates and post graduate researchers—as well as those in various areas of African studies.
The Relations between Logic and Philosophy, 1874-1931
This chapter gives a survey of the field of philosophy where the philosophical foundations of modern logic were discussed and where such themes of logic were discussed that were on the borderline between logic and other branches of the philosophical enterprise, such as metaphysics and epistemology. The contributions made by Gottlob Frege and Charles Peirce are included since their work in logic is closely related to and also strongly motivated by their philosophical views and interests. In addition, the chapter pays attention to a few philosophers to whom logic amounted to traditional Aristotelian logic and to those who commented on the nature of logic from a philosophical perspective without making any significant contribution to the development of formal logic.
Logic and Philosophy of Logic from Humanism to Kant
This chapter begins with a discussion of humanist criticisms of scholastic logic. It then discusses the evolution of the scholastic tradition and the influence of Renaissance Aristotelianism, Descartes and his influence, the Port-Royal Logic, the emergence of a logic of cognitive faculties, logic and mathematics in the late 17th century, Gottfried Wilhelm Leibniz’s role in the history of formal logic, and Kant’s influence on logic.
Indian Logic
The chapter is an overview of Indian logic, with a general introduction followed by specialized sections on four different schools: Nyāya logic, Buddhist logic, Jaina logic, and Navya-Nyāya logic.
Indicative Conditionals
The chapter is an introduction to logical treatments of indicative conditionals, comparing truth-functional, non-truth-functional, and suppositional approaches. Some of the topics discussed are truth conditions, conditional belief, assertability, and issues with compounds of conditionals.
Logic and Natural Language
Logicians have always found inspiration for new research in the ordinary language that is used on a daily basis and acquired naturally in childhood. Whereas the logical issues in the foundations of mathematics motivated the development of mathematical logic with its emphasis on notions of proof, validity, axiomatization, decidability, consistency, and completeness, the logical analysis of natural language motivated the development of philosophical logic with its emphasis on semantic notions of presupposition, entailment, modality, conditionals, and intensionality. The relation between research programs in both mathematical and philosophical logic and natural language syntax and semantics as branches of theoretical linguistics has increased in importance throughout the last fifty years. This chapter reviews the development of one particularly interesting and lively area of interaction between formal logic and linguistics—the semantics of natural language. Research in this emergent field has proved fruitful for the development of empirically, cognitively adequate models of reasoning with partial information, sharing or exchanging information, dynamic interpretation in context, belief revision and other cognitive processes.
Truth
The concept of truth serves in logic not only as an instrument but also as an object of study. Eubulides of Miletus (fl. fourth century BCE), a Megarian logician, discovered the paradox known as ‘the Liar,’ and, ever since his discovery, logicians down the ages – Aristotle and Chrysippus, John Buridan and William Heytesbury, and Alfred Tarski and Saul Kripke, to mention just a few – have tried to understand the puzzling behavior of the concept of truth.