Introduction
From terms and propositions through sign arithmetic, syllogisms, and singular terms — a complete algebraic account of categorical logic.
Start course →The Full Language
Compound statements, 'or,' relational terms, passive transformation, and proterms — the complete extension of TFL's sign algebra, plus the deeper story of why REGAL works.
Start course →Relational Syllogisms
Inference with relational terms: the dictum de omni reaching inside relational complexes, distribution made precise, and indirect proof — including De Morgan's famous horse's-head argument.
Start course →Statement Logic and the MPL Bridge
The trichotomy of tautology, contradiction, and contingency; direct proofs and the tree method; disjunctive normal form; the translation bridge to modern predicate logic — and the intermediate quantifiers most, many, and few.
Start course →The TFL Lab
Run the algebra all four courses taught: write a fact base in course notation, ask what follows, and watch every answer explain itself — derivations, refutations, consistency, and the Aristotelian "perhaps."
Open the lab →