Barcan formula

Barcan formula
A fundamental thesis in quantified modal logic, first isolated by the 20th-century American philosopher Ruth Barcan Marcus. It was originally the schema that ⋄(∃x )A x strictly implies (∃x )⋄Ax (informally: if possibly something is A, then something is possibly A). Adding this to a standard modal logic is equivalent to adding ⋄(∃x )A x → (∃x )⋄ A x or (∀x )⎕F x → ⎕(∀x )F x, and either of these may be called the Barcan formula. Informally the latter means that if everything is necessarily F, then necessarily everything is F. The formula has been criticized on the grounds that when we consider possible worlds with different objects in them, then although the antecedent might be true of the actual world, the consequent may be false. For instance, it may be possible that there should be things of a different species from any actual living organism, but not possible of any living organism that it should be of a different species.

Philosophy dictionary. . 2011.

Look at other dictionaries:

  • Barcan formula — In quantified modal logic, the Barcan formula and the converse Barcan formula (more accurately, schemata rather than formulae) (i) syntactically state principles or interchange between quantifiers and modalities; (ii) semantically state a… …   Wikipedia

  • Ruth Barcan Marcus — (born 1921 in Bronx, New York) is the American philosopher and logician after whom the Barcan formula is named. She is a pioneering figure in the quantification of modal logic and the theory of direct reference. She has written seminal papers on… …   Wikipedia

  • MARCUS, RUTH BARCAN — (1921– ), U.S. logician and philosopher who played a key role in many of the philosophical debates of the second half of the 20th century. Born and educated in New York City, Ruth Barcan received her B.A. in mathematics and philosophy from New… …   Encyclopedia of Judaism

  • List of topics in logic — This is a list of topics in logic.See also: List of mathematical logic topicsAlphabetical listAAbacus logic Abduction (logic) Abductive validation Affine logic Affirming the antecedent Affirming the consequent Antecedent Antinomy Argument form… …   Wikipedia

  • Max Cresswell — Max John Cresswell (* 19. November 1939 in Wellington) ist ein neuseeländischer Philosoph und Logiker, der sich insbesondere mit der Philosophie der Logik, Modallogik und formaler Semantik beschäftigt. Daneben hat Cressell auch zur Philosophie… …   Deutsch Wikipedia

  • De dicto et de re — sont deux locutions distinguant deux modalités importantes des énoncés, ainsi que les raisonnements qui s ensuivent. Ces distinctions relèvent de la logique, de la rhétorique, de la linguistique et de la métaphysique. La traduction littérale de… …   Wikipédia en Français

  • List of philosophy topics (A-C) — 110th century philosophy 11th century philosophy 12th century philosophy 13th century philosophy 14th century philosophy 15th century philosophy 16th century philosophy 17th century philosophy 18th century philosophy 19th century philosophy220th… …   Wikipedia

  • De dicto and de re — are two phrases used to mark important distinctions in intensional statements, associated with the intensional operators in many such statements. The distinctions are most recognized in philosophy of language and metaphysics. The literal… …   Wikipedia

  • Modal logic — is a type of formal logic that extends classical propositional and predicate logic to include operators expressing modality. Modals words that express modalities qualify a statement. For example, the statement John is happy might be qualified by… …   Wikipedia

  • Tautología — Para otros usos de este término, véase Tautología (retórica). En lógica, una tautología (del griego ταυτολογία, decir lo mismo ) es una fórmula bien formada de un sistema de lógica proposicional que resulta verdadera para cualquier… …   Wikipedia Español

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.