Duality in Logic and Language Duality phenomena occur in nearly all mathematically formalized disciplines, such as algebra, geometry, logic and natural language semantics. However, many of these disciplines use the term ‘duality’ in vastly different senses, and while some of these senses are intimately connected to each other, others seem to be entirely unrelated. Consequently, if the term ‘duality’ is used in two different senses

Kristina Wasa (1626—1689) The flamboyant life of Kristina, the Queen of Sweden, one of Europe’s most mercurial monarchs, has long overshadowed her contribution to philosophy. When histories of philosophy mention her at all, they usually present her as the pupil of Descartes and as the patron of philosophical salons. But Kristina’s relationship to philosophy transcends her auxiliary roles.  In her writings she makes her own

Epiphenomenalism Epiphenomenalism is a position in the philosophy of mind according to which mental states or events are caused by physical states or events in the brain but do not themselves cause anything. It seems as if our mental life affects our body, and, via our body, the physical world surrounding us: it seems that sharp pains make us wince, it seems that fear makes

St. Louis Hegelians The common name given to a group of amateur philosophers founded and led by William Torrey Harris (1835-1909) and Henry Conrad Brokmeyer (1828-1906). Harris, a New Englander born in Connecticut and educated at Yale, first became acquainted with idealism through the Transcendentalists, mainly from his attendance in 1857 at the Orphic Seer’s Conversations of Amos Bronson Alcott (1799-1888). The experience inspired Harris

Leibniz: Logic The revolutionary ideas of Gottfried Wilhelm Leibniz (1646-1716) on logic were developed by him between 1670 and 1690. The ideas can be divided into four areas: the Syllogism, the Universal Calculus, Propositional Logic, and Modal Logic. These revolutionary ideas remained hidden in the Archive of the Royal Library in Hanover until 1903 when the French mathematician Louis Couturat published the Opuscules et fragments inédits de Leibniz.

Avicenna (Ibn Sina): Logic         Avicenna (Ibn Sina) (c. 980-1037 C.E., or 375-428 of Hegira) is one of the most important philosophers and logicians in the Arabic world. His logical works are presented in several treatises. Some of them are commentaries on Aristotle’s Organon, and are presented in al-Shifa al-Mantiq, the logical part of the Encyclopedic Book al-Shifa (The Cure), which also contains a