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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.

See also

  • Adjunctioninclusive disjunction: A or B (or both)
  • Contravalence - exclusive disjunction: A or B (but not both)

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Ad Hominem Info is a project to explain and categorize the most common systematic fallacies and fallacies. On this page, you will find a background article that briefly explains an important logical concept, which may be needed to better understand another article in this area.
For more information, please see the main category “logic

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