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Disjunction is the combination of two sentences with or. In propositional logic, the disjunction of two formulas phi and psi, written phi v psi, is true if phi is true or psi is true or both, as is shown in the truth-table (i):

(i)  phi		psi	phi v psi
      1			 1	    1
      1			 0	    1
      0			 1	    1
      0			 0	    0

This version of disjunction is called inclusive, because it allows the propositions phi and psi both to be true. Natural language or can also be used exclusively: only one of the two propositions may be true, but not both (either ... or ...).


Utrecht Lexicon of Linguistics


  • Gamut, L.T.F. 1991. Logic, language, and meaning, Univ. of Chicago Press, Chicago.