An Interpretation Of Peirce's Existential Graphs

Abstract

The American philosopher Charles Sanders Peirce has come to be regarded as one of the founding fathers of modern day logic. One of his most original contributions is the logical system called existential graphs. Through the existential graphs, Peirce sought a means of evaluating the workings of necessary inference. Peirce develops the existential graphs in three sections, the alpha graphs, beta graphs, and gamma graphs. The purpose of this study is to offer a coherent interpretation, complete with examples, of Peirce’s existential graphs. A careful evaluation of Peirce's notes on the existential graphs shows the alpha graphs to be a version of propositional logic and the beta graphs to be a version of quantificational logic. The gamma graphs, however, are not as fully developed as modern day modal logic.