Christine Ladd propôs, em 1881, um tratamento da Silogística Categórica, conhecido como “Antilogismo”, que consiste no teste de inconsistência da tríade de proposições categóricas formada pelas premissas e pela negação da conclusão de um Silogismo. A vantagem desse tratamento consiste em utilizar uma única forma válida, se o Antilogismo é expresso em termos algébricos. Utilizo ideias incorporadas em métodos diagramáticos que desenvolvi para a Silogística Categórica – o Método de Gardner e o Método de Gardner-Peirce – para fornecer uma expressão (...) gráfica ao Antilogismo de Ladd. (shrink)

This anthology is a thorough introduction to classic literature for those who have not yet experienced these literary masterworks. For those who have known and loved these works in the past, this is an invitation to reunite with old friends in a fresh new format. From Shakespeare's finesse to Oscar Wilde's wit, this unique collection brings together works as diverse and influential as The Pilgrim's Progress and Othello. As an anthology that invites readers to immerse themselves in the masterpieces of (...) the literary giants, it is must-have addition to any library. (shrink)

Conclusão e Premissas negociam peças de informação entre si. Conclusão carece delas, Premissas dispõe delas. O saldo entre carência e disponibilidade exige aferição. O método heterogêneo de prova para a Lógica Sentencial Clássica, aqui desenvolvido, implementa esta metáfora. Ele pode ser empregado solitário, cooperativa, ou competitivamente.

The two works reprinted in this volume are a unique fusion of logical thought and inimitable whimsy. Written by the 19th-century mathematician who also gave us "Alive in Wonderland", they are among the most entertaining logical works ever written, and contain some of the most thought-provoking puzzles ever devised.

O Método de Gardner – um método por dígrafos para a Silogística – implementa a concepção de proposições categóricas como expressões de subordinação e de não-subordinação entre pares de conceitos; nele, a representação das proposições universais é mais complexa do que a representação das proposições particulares. Neste trabalho desenvolverei uma implementação da Silogística na qual as proposições categóricas são expressões de instanciação e de não-instanciação de pares de conceitos. Adaptarei o Sistema Beta dos Grafos Existenciais de Peirce ao Método de (...) Gardner. Essa adaptação tem o mérito de igualar a complexidade da representação das proposições categóricas, mas introduz outros inconvenientes. (shrink)

In 1883, while a student of C. S. Peirce at Johns Hopkins University, Christine Ladd-Franklin published a paper titled On the Algebra of Logic, in which she develops an elegant and powerful test for the validity of syllogisms that constitutes the most significant advance in syllogistic logic in two thousand years. Sadly, her work has been all but forgotten by logicians and historians of logic. Ladd-Franklin's achievement has been overlooked, partly because it has been overshadowed by the work of other (...) logicians of the nineteenth century renaissance in logic, but probably also because she was a woman. Though neglected, the significance of her contribution to the field of symbolic logic has not been diminished by subsequent achievements of others.In this paper, I bring to light the important work of Ladd-Franklin so that she is justly credited with having solved a problem over two millennia old. First, I give a brief survey of the history of syllogistic logic. In the second section, I discuss the logical systems called “algebras of logic”. I then outline Ladd-Franklin's algebra of logic, discussing how it differs from others, and explain her test for the validity of the syllogism, both in her symbolic language and the more familiar language of modern logic. Finally I present a rigorous proof of her theorem. Ladd-Franklin developed her algebra of logic before the methods necessary for a rigorous proof were available to her. Thus, I do now what she could not have done then. (shrink)