##  [Modal Logic](/index.php/modal-logic) 

  ##  [Modal Logic](https://mathlogic.quantumdictionary.io/modal-logic-0) 

  

 [![Mathematics & Logic Dictionary](/sites/default/files/styles/large/public/2026-01/Mathematics%20%26%20Logic.png.webp?itok=UhtTRPnp)](/index.php/topic-specific-dictionaries/natural-formal-sciences/mathematics-logic)

- Natural & Formal Sciences -

**Mathematics & Logic Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A family of formal logics that extend propositional or predicate calculi with modal operators (such as □ for necessity and ◇ for possibility) to express modes of truth relative to points in a model equipped with an accessibility relation.

 

 

 

 

 





 

 



 ##  [Modal Logic](https://humanitites.quantumdictionary.io/modal-logic-1) 

  

 [![Humanities & Arts Dictionary](/sites/default/files/styles/large/public/2026-01/Humanities%20%26%20Arts.png.webp?itok=4SMNHqFS)](/index.php/topic-specific-dictionaries/humanities-arts)



**Humanities & Arts Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A family of formal systems that extend classical propositional or predicate logic by introducing modal operators (commonly read as necessity □ and possibility ◇) and specifying their syntax, axioms and semantics—typically via relational (possible‑world) models or other frame structures—to analyze modal notions such as necessity, possibility, obligation, knowledge and temporal modalities.