KnowraPrincipia MathematicaLinked fromLinked fromThe 25 pages that link to Principia Mathematica, each with the reason it gives.All 25Broader topic 4Related 18Compared with 3Well-ordering theoremCompared with: Its foundational program illustrates an alternative context to the set-theoretic axioms behind the theorem.Axiom of extensionalityCompared with: Its treatment of classes and identity illustrates a different foundational setting from modern set axioms.Axiom of Empty SetCompared with: Its type-theoretic foundation approaches existence without the same set-theoretic axiom list.