Logical value

In logic and mathematics, a logical value, also called a truth value, is a value indicating the extent to which a proposition is true.

In classical logic, the only possible truth values are true and false. However, other values are possible in other logics: fuzzy logic and other forms of multi-valued logic use more truth values than simply true and false.

Algebraically, the set {true, false} forms a two-element Boolean algebra. Other kinds of algebras may be used as sets of truth values in non-classical logics: for instance, intuitionistic logic uses Heyting algebras.

In topos theory, the subobject classifier of a topos takes the place of the set of truth values.


 * The truth value of a proposition is shown using 0s and 1s.
 * True = 1
 * False = 0