Affirming a disjunct
The formal fallacy of affirming a disjunct, also known as the fallacy of the alternative disjunct or a false exclusionary disjunct, occurs when a deductive argument takes the following logical form: A or B A Therefore, not B Or in logical operators: p ∨ q {\displaystyle p\vee q} p {\displaystyle p} ⊢ {\displaystyle {}\vdash {}} ¬ q {\displaystyle q} Where ⊢ {\displaystyle {}\vdash {}} denotes a logical assertion. == Explanation == The fallacy lies in concluding that one disjunct must be false because the other disjunct is true; in fact they may both be true because "or" is defined inclusively rather than exclusively.