Education and career
John Etchemendy received his bachelor's and master's degrees at the University of Nevada, Reno, before earning his PhD in philosophy at Stanford in 1982.
He has been a faculty member in Stanford's Department of Philosophy since 1983, prior to which he was a faculty member in the Philosophy Department at Princeton University. He is also a faculty member of Stanford's Symbolic Systems Program and a senior researcher at the Center for the Study of Language and Information at Stanford.
At Stanford, Etchemendy served as director of the Center for the Study of Language and Information from 1990 to 1993, senior associate dean in the School of Humanities and Sciences from 1993 to 1997, and chair of the Department of Philosophy from 1998 to 2000.
He is a member of the American Philosophical Association, on the editorial boards of Synthese and Philosophia Mathematica, and a former editor of the Journal of Symbolic Logic. His wife is the writer Nancy Etchemendy and they have one son Max Etchemendy.
Philosophical work
Etchemendy's research interests include logic, semantics and the philosophy of language. He has challenged orthodox views on the central notions of truth, logical consequence and logical truth. His most well-known book, The Concept of Logical Consequence (1990, 1999), criticizes Alfred Tarski's widely accepted analysis of logical consequence. The Liar: An essay on truth and circularity (1987, 1992), co-authored with the late Jon Barwise, develops a formal account of the liar paradox modelled using a version of set theory incorporating the so-called Anti-Foundation Axiom.
Etchemendy's recent work has focused on the role of diagrams and other nonlinguistic forms of representation in reasoning. His latest book, written with Jon Barwise and Dave Barker-Plummer, is Language, Proof and Logic (2000, 2006), a popular introductory logic textbook. He has also developed numerous pieces of instructional software, including Turing's World, Tarski's World,Fitch, and Hyperproof, software that allows computers to support the reasoning process.
In philosophy and logic, the classical liar paradox or liar's paradox or antinomy of the liar is the statement of a liar that they are lying: for instance, declaring that "I am lying". If the liar is indeed lying, then the liar is telling the truth, which means the liar just lied. In "this sentence is a lie" the paradox is strengthened in order to make it amenable to more rigorous logical analysis. It is still generally called the "liar paradox" although abstraction is made precisely from the liar making the statement. Trying to assign to this statement, the strengthened liar, a classical binary truth value leads to a contradiction.
Rudolf Carnap was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism.
Alfred Tarski was a Polish-American logician and mathematician. A prolific author best known for his work on model theory, metamathematics, and algebraic logic, he also contributed to abstract algebra, topology, geometry, measure theory, mathematical logic, set theory, and analytic philosophy.
The history of logic deals with the study of the development of the science of valid inference (logic). Formal logics developed in ancient times in India, China, and Greece. Greek methods, particularly Aristotelian logic as found in the Organon, found wide application and acceptance in Western science and mathematics for millennia. The Stoics, especially Chrysippus, began the development of predicate logic.
Kenneth Jon Barwise was an American mathematician, philosopher and logician who proposed some fundamental revisions to the way that logic is understood and used.
In logic, a true/false decision problem is decidable if there exists an effective method for deriving the correct answer. Zeroth-order logic is decidable, whereas first-order and higher-order logic are not. Logical systems are decidable if membership in their set of logically valid formulas can be effectively determined. A theory in a fixed logical system is decidable if there is an effective method for determining whether arbitrary formulas are included in the theory. Many important problems are undecidable, that is, it has been proven that no effective method for determining membership can exist for them.
Non-well-founded set theories are variants of axiomatic set theory that allow sets to be elements of themselves and otherwise violate the rule of well-foundedness. In non-well-founded set theories, the foundation axiom of ZFC is replaced by axioms implying its negation.
In logic and mathematics, a formal proof or derivation is a finite sequence of sentences, each of which is an axiom, an assumption, or follows from the preceding sentences in the sequence by a rule of inference. It differs from a natural language argument in that it is rigorous, unambiguous and mechanically verifiable. If the set of assumptions is empty, then the last sentence in a formal proof is called a theorem of the formal system. The notion of theorem is not in general effective, therefore there may be no method by which we can always find a proof of a given sentence or determine that none exists. The concepts of Fitch-style proof, sequent calculus and natural deduction are generalizations of the concept of proof.
The philosophy of information (PI) is a branch of philosophy that studies topics relevant to information processing, representational system and consciousness, cognitive science, computer science, information science and information technology.
Gila Sher is an American logician and professor of philosophy at the University of California, San Diego. She has worked extensively in the theory of truth and philosophy of logic. Sher is a leading advocate of foundational holism, a holistic theory of epistemology.
In situation theory, situation semantics attempts to provide a solid theoretical foundation for reasoning about common-sense and real world situations, typically in the context of theoretical linguistics, theoretical philosophy, or applied natural language processing,
In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. It is not required for a valid argument to have premises that are actually true, but to have premises that, if they were true, would guarantee the truth of the argument's conclusion. Valid arguments must be clearly expressed by means of sentences called well-formed formulas.
Philosophy of logic is the area of philosophy that studies the scope and nature of logic. It investigates the philosophical problems raised by logic, such as the presuppositions often implicitly at work in theories of logic and in their application. This involves questions about how logic is to be defined and how different logical systems are connected to each other. It includes the study of the nature of the fundamental concepts used by logic and the relation of logic to other disciplines. According to a common characterisation, philosophical logic is the part of the philosophy of logic that studies the application of logical methods to philosophical problems, often in the form of extended logical systems like modal logic. But other theorists draw the distinction between the philosophy of logic and philosophical logic differently or not at all. Metalogic is closely related to the philosophy of logic as the discipline investigating the properties of formal logical systems, like consistency and completeness.
John Corcoran was an American logician, philosopher, mathematician, and historian of logic. He is best known for his philosophical work on concepts such as the nature of inference, relations between conditions, argument-deduction-proof distinctions, the relationship between logic and epistemology, and the place of proof theory and model theory in logic. Nine of Corcoran's papers have been translated into Spanish, Portuguese, Persian, and Arabic; his 1989 "signature" essay was translated into three languages. Fourteen of his papers have been reprinted; one was reprinted twice.
Language, Proof and Logic is an educational software package, devised and written by Jon Barwise and John Etchemendy, geared to teaching formal logic through the use of a tight integration between a textbook and four software programs, where three of them are logic related and the other (Submit) is an internet-based grading service. The name is a pun derived from Language, Truth, and Logic, the philosophy book by A. J. Ayer.
In propositional logic, tautological consequence is a strict form of logical consequence in which the tautologousness of a proposition is preserved from one line of a proof to the next. Not all logical consequences are tautological consequences. A proposition is said to be a tautological consequence of one or more other propositions in a proof with respect to some logical system if one is validly able to introduce the proposition onto a line of the proof within the rules of the system; and in all cases when each of are true, the proposition also is true.
Logical consequence is a fundamental concept in logic which describes the relationship between statements that hold true when one statement logically follows from one or more statements. A valid logical argument is one in which the conclusion is entailed by the premises, because the conclusion is the consequence of the premises. The philosophical analysis of logical consequence involves the questions: In what sense does a conclusion follow from its premises? and What does it mean for a conclusion to be a consequence of premises? All of philosophical logic is meant to provide accounts of the nature of logical consequence and the nature of logical truth.
Tarski's World is a computer-based introduction to first-order logic written by Jon Barwise and John Etchemendy. It is named after the mathematical logician Alfred Tarski. The package includes a book, which serves as a textbook and manual, and a computer program which together serve as an introduction to the semantics of logic through games in which simple, three-dimensional worlds are populated with various geometric figures and these are used to test the truth or falsehood of first-order logic sentences. The program is also included in Language, Proof and Logic package.
Anil K. Gupta is an Indian-American philosopher who works primarily in logic, epistemology, philosophy of language, and metaphysics. Gupta is the Alan Ross Anderson Distinguished Professor of Philosophy at the University of Pittsburgh. He is also a Fellow of the American Academy of Arts and Sciences. His most recent book, Conscious Experience: A Logical Inquiry, was published by Harvard University Press in 2019.
Sun-Joo Shin is a Korean-American philosopher known for her work on diagrammatic reasoning in mathematical logic, including the validity of reasoning using Venn diagrams, the existential graphs of Charles Sanders Peirce, and the philosophical distinction between diagrammatic and symbolic reasoning. She is a professor of philosophy at Yale University.
