In Logic the term ‘disjunction’ is used to designate one of five functions
in Propositional Logic where at least one atomic
propositions that compose a compound proposition is
For example, take the following two simple propositions:
These two simple (or atomic)
propositions can be disjoined to form the compound proposition, Kato is a dog or Kato is a mammal.
By disjoining the simple propositions into a single compound proposition we are claiming that one of the elements is true (and it
does not matter which).
- Kato is a dog.
- Kato is a mammal.
Every proposition, whether simple or compound, has a truth value, the
disjunction of two propositions will be true
in all cases but one: when neither component is true.
In ordinary language there are different words that serve the logical function of disjunction: ‘or’ and ‘unless’, etc.