Language, Proof and Logic

Language, Proof and Logic is an educational software package, devised and written by Jon Barwise and John Etchemendy, geared to teaching formal logic through the use of a tight integration between a textbook (same name as the package) and four software programs, where three of them are logic related (Boole, Fitch and Tarski's World) and the other (Submit) is an internet-based grading service. The name is a pun derived from Language, Truth, and Logic, the philosophy book by A. J. Ayer.

On September 2, 2014, there was launched a massive open online course (MOOC) with the same name, which utilizes this educational software package.


A short description of the programs:

  • Boole (named after George Boole) - a program that facilitates the construction and checking of truth tables and related notions (tautology, tautological consequence, etc.);
  • Fitch (named after Frederic Brenton Fitch) - a natural deduction proof environment in Fitch-style calculus for giving and checking first-order proofs;
  • Tarski's World (named after Alfred Tarski) - a program that teaches the basic first-order language and its semantics using a model theoretic-like approach, where the "world" consists of a little grid and some simple objects;
  • Submit - a program that allows students to submit exercises done with the above programs to the Grade Grinder, the online grading service.[1]


  1. ^ Grim, P. (2001). "Language, Proof and Logic". The Bulletin of Symbolic Logic. 7 (3): 377–379. doi:10.2307/2687756. JSTOR 2687756.

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