Interested in completely free, browser-based, instructional logic software? Brian Rabern spent a decade at the University of Edinburgh working in logic, formal semantics, and other areas of philosophy before moving into the tech world. Unable to find logic software that met his needs, he and a former student created Elogic. Initially developed for his courses, it has since been used at several universities. He is now making the software freely available to anyone who wants to use it. He describes it below. Elogic: Free Web-Based Logic Software by Brian Rabern I taught introductory logic to large classes (400-500 students) for over a decade. The desktop software I inherited worked, but supporting it was a headache: install conflicts, only supported on certain devices, students fighting IT on shared machines. In 2014 a student in my class and I started building a web-based replacement. That became Elogic. It’s a browser-based environment for logic exercises with immediate, automated feedback. There’s nothing to install, and it works on anything with a browser. The guiding design idea was to make something genuinely intuitive for first-year philosophy students, the students who are there for epistemology or ethics or Nietzsche and encountering formal notation for the first time. The interface should get out of the way, not add a learning curve on top of the logic itself. 1. What it does Four core exercise types: Symbolizations. Translate English into propositional or first-order logic. Answers are checked for logical equivalence (using an SMT solver), not exact match to one official answer. Feedback distinguishes syntax errors from meaning errors. Derivations. Natural deduction proofs in a Fitch-style layout. Guided feedback on rule use, scope, and variable capture. Supports rule-locking: derived rules are withheld until prerequisite theorems are proved. Truth tables. Row-by-row feedback on missing or wrong values. Countermodels. Build an interpretation that makes the premises true and the conclusion false. Checked automatically via SMT solver. 2. Scope and limitations Elogic is opinionated. The natural deduction system is Kalish-Montague style in Fitch format, aligned specifically with Parsons’s An Exposition of Symbolic Logic. The notation, rule names, and proof conventions match that presentation. This is designed for courses using that text or something close to it, not as a general-purpose tool configurable..

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