Buridan formula

== English == === Etymology === Named in honour of the medieval philosopher Jean Buridan. === Proper noun === the Buridan formula (logic) In quantified modal logic, the formula ◊ ∀ x F x → ∀ x ◊ F x {\displaystyle \Diamond \forall xFx\rightarrow \forall x\Diamond Fx} , meaning "if possibly everything is F, then everything is possibly F".