#### Faculty Advisor

Cannon, Douglas

#### Area of Study

Arts, Humanities and Social Sciences

#### Publication Date

Summer 2016

#### Abstract

In the beginning of the 20th century, many prominent logicians and mathematicians, such as Frege, Russell, Hilbert, and many others, felt that mathematics needed a very rigorous foundation in logic. Many results of the time were motivated by questions about logical truth and logical consequence. The standard approach in the early part of the 20th century was to use a syntactic or proof-theoretic definition of logical consequence. This says that "for one sentence to be a logical consequence of [a set of premises] is simply for that sentence to be derivable from [them] by means of some standard system of deduction" (Etchemendy 1988). However, many famous results of the time, especially Gödel's incompleteness theorems led to logicians such as Tarski to define logical consequence with what was eventually developed into the standard ``model-theoretic" definition. This way of defining logical consequence says that a argument of a certain form is a logically valid argument if it is *impossible* for the premises to be true and the conclusion false (Mates 1972, Cannon 2016). Many philosophers have written about the effectiveness of this definition, but in 1990 John Etchemendy offered a fundamental criticism of Tarski's definition both as to whether it is conceptually correct, and whether it captures the right set of arguments, or interpretations. This paper explores Etchemendy's argument and various responses from prominent philosophers.

#### Recommended Citation

Jenks, Jesse Endo, "What Do We Mean by Logical Consequence?" (2016). *Summer Research*. 276.

http://soundideas.pugetsound.edu/summer_research/276

#### Publisher

University of Puget Sound