KnowraSecond-order logicLinked fromLinked fromThe 13 pages that link to Second-order logic, each with the reason it gives.All 13Broader topic 2Related 2Narrower topic 1Compared with 8First-order logicCompared with: It expresses some structural claims unavailable to first-order quantification over objects alone.Model theoryCompared with: Its greater expressive power comes with different completeness and compactness behavior.Predicate logicBroader topic: It expands first-order predicate logic by quantifying over properties and relations.Compactness theoremCompared with: Under standard semantics, second-order logic does not have the first-order compactness property.Universal quantificationCompared with: Quantifying over properties can express claims that first-order universal quantification cannot capture categorically.LogicismRelated: Frege’s arithmetic depends on second-order principles stronger than ordinary first-order logic.Peano axiomsRelated: Its induction axiom quantifies over every property, giving the natural numbers a categorical characterization.Axiom schemaCompared with: Some principles expressed by schemas in first-order logic can be stated with second-order quantifiers.Higher-order logicBroader topic: It is the most familiar level in the hierarchy of higher-order logics.Tarski's axiomsCompared with: Second-order axioms can express geometric continuity more categorically than first-order formulations.Skolem's paradoxCompared with: Full second-order semantics changes the range of quantification, but does not make the first-order result contradictory.Frege's theoremNarrower topic: The theorem's strength comes from quantifying over concepts, not individuals alone.Lindström's theoremCompared with: Its greater expressive power comes at the cost of first-order compactness under standard semantics.