A false dilemma is an argument that presents a limited set of two possible categories and assumes that everything in the scope of the discussion must be an element of that set. Thus, by rejecting one category, you are forced to accept the other. For example, "In the war on fanaticism, there are no sidelines; you are either with us or with the fanatics." In reality, there is a third option, one could very well be neutral; and a fourth option, one may be against both; and even a fifth option, one may empathize with elements of both.
Ali Almossawi, An Illustrated Book of Bad Arguments: Learn the Lost Art of Making Sense (2013)