Disjunction

A logical proposition that connects two terms with an “or”. This can be in the form of an inclusive, or an exclusive “or”.

Example for an inclusive disjunction (adjunction):

Would you like sugar or milk in your coffee [or both]?

Example for an exclusive disjunction (contravalence):

You can have ice cream or fruit salad for dessert [but not both].

The term “disjunction” is here used as a general term for two different (though closely related) logical forms that are both expressed with the same word (“or”) in common English.

Note: The term “disjunction” is also sometimes used specifically as a synonym to “adjunction”, i.e. to refer to inclusive disjunction. This can however cause confusion and is not recommended.

For more information, see the articles on adjunction and contravalence.

• Adjunction – inclusive disjunction: A or B (or both)
• Contravalence - exclusive disjunction: A or B (but not both)

• Affirming a disjunct
• Conjunction

• Logical disjunction on Wikipedia