In
Aristotelean logic,
dictum de omni et nullo (
Latin: "the maxim of all and none") is the principle that whatever is affirmed or denied of a whole kind K may be affirmed or denied (respectively) of any subkind of K. This principle is fundamental to
syllogistic logic in the sense that all valid syllogistic argument forms are reducible to applications of the two constituent principles
dictum de omni and
dictum de nullo.