The logical fallacy of false dilemma (also called false dichotomy, the either-or fallacy) involves a situation in which only two alternatives are considered, when in fact there are other options. Closely related are failing to consider a range of options and the tendency to think in extremes, called black-and-white thinking. Strictly speaking, the prefix "di" in "dilemma" means "two". When a list of more than two choices is offered, but there are other choices not mentioned, then the fallacy is called the fallacy of false choice, or the fallacy of exhaustive hypotheses.
False dilemma can arise intentionally, when fallacy is used in an attempt to force a choice ("If you are not with us, you are against us.") But the fallacy can arise simply by accidental omission—possibly through a form of wishful thinking or ignorance—rather than by deliberate deception ("I thought we were friends, but all my friends were at my apartment last night and you weren't there.")
When two alternatives are presented, they are often, though not always, two extreme points on some spectrum of possibilities. This can lend credence to the larger argument by giving the impression that the options are mutually exclusive, even though they need not be. Furthermore, the options are typically presented as being collectively exhaustive, in which case the fallacy can be overcome, or at least weakened, by considering other possibilities, or perhaps by considering a whole spectrum of possibilities, as in fuzzy logic.
f80 AW/SO 6MT PCD Dec 2015 | f30 | e92 | tt | S5 | e92 | 350z | e90 |