Disjunction introduction or addition is a simple valid argument form, an immediate inference and a rule of inference of propositional logic. The rule makes it possible to introduce disjunctions to logical proofs. It is the inference that if P is true, then P or Q must be true.
- Socrates is a man.
- Therefore, either Socrates is a man or pigs are flying in formation over the English Channel.
The rule can be expressed as:
where the rule is that whenever instances of "" appear on lines of a proof, "" can be placed on a subsequent line.
Disjunction introduction is controversial in paraconsistent logic because in combination with other rules of logic, it leads to explosion (i.e. everything becomes provable). See Tradeoffs in Paraconsistent logic.
Read more about Disjunction Introduction: Formal Notation
Famous quotes containing the word introduction:
“My objection to Liberalism is this—that it is the introduction into the practical business of life of the highest kind—namely, politics—of philosophical ideas instead of political principles.”
—Benjamin Disraeli (1804–1881)