A formal argument in logic in which it is stated that (1) 
and 
(where 
means "implies"), and (2) either 
or 
is true, from which two statements it follows that either
or 
is true.
Constructive Dilemma
See also
Destructive Dilemma, DilemmaExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Constructive Dilemma." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ConstructiveDilemma.html