False dilemma

The informal 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 are offered, but there are other choices not mentioned, then the fallacy is called the fallacy of false choice.

When a person really does have only two choices, as in the classic short story The Lady, or the Tiger?, then they are often said to be "on the horns of a dilemma".

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.

Examples

Morton's Fork

Very often a Morton's Fork, a choice between two equally unpleasant options, is a false dilemma. The phrase originates from an argument for taxing English nobles:

"Either the nobles of this country appear wealthy, in which case they can be taxed for good; or they appear poor, in which case they are living frugally and must have immense savings, which can be taxed for good."

This is a false dilemma, because some members of the nobility may in fact lack liquid assets.

False choice

The presentation of a false choice often reflects a deliberate attempt to eliminate the middle ground on an issue. Eldridge Cleaver used such a quotation during his 1968 presidential campaign: "You're either part of the solution or part of the problem." This quotation was in turn a variation from The Guthrian seven years earlier: "Every person is either part of the problem, or part of the solution."

A common argument against noise pollution laws involves a false choice. In New York City, some say that noise shouldn't be regulated, because if it were, the city would drastically change in a negative way. It involves assuming that for example: a bar must be shut down for it to not cause disturbing levels of noise after midnight. This ignores the fact that the bar could simply lower its noise levels, and/or install more soundproof structural elements to keep the noise from excessively transmitting onto others properties.

Black and white thinking

A common form of the false dilemma is black-and-white thinking. Many people routinely engage in black-and-white thinking, an example of which is feeling boundless optimism when things are going well and suddenly switching to total despair at the first setback. Another example is someone who labels other people as all good or all bad.

Falsus in unus, falsus omnibus

This Latin phrase means "false in one thing, false in everything", and it is often used to label someone found to be wrong on one issue to also be wrong with regard other issues. This is a logical fallacy because being found incompetent in one respect does not imply that one is incompetent in all other respects. This is an example of an ad hominem argument and a special case of the association fallacy.

There is no alternative

The assertion that there is no alternative is an example of the false dichotomy taken to its ultimate extreme, in which the options are reduced to one, the proposal of the speaker. Of course the speaker does not believe there are no alternatives otherwise theywould not bother to argue the point; rather they oppose the alternatives and seeks to dismiss them by denying their existence.

"This was the mantra chanted by 'dries' during the prime ministerial reign of Margaret Thatcher, by which they demonstrated their belief that free-market capitalism was the only possible economic theory. It was said so often amongst them that it was shortened to TINA. The hard-right Thatcherites called themselves 'dries' to demonstrate their opposition to the 'wets', i.e. the One-Nation Tories whom Thatcher despised. Wet was the public school nickname for any boy who showed any sign of caring for his fellow beings."

See also

• Bivalence
• Correlative-based fallacies
• Degrees of truth
• Fuzzy logic
• Law of excluded middle

• Nondualism
• Pascal's Wager
• Nolan chart
• Half-truths
• Multivalued logic

• Perspectivism
• Principle of bivalence
• Rogerian argument
• Sorites paradox
• You're either with us, or against us

External links

• The Black-or-White Fallacy entry in The Fallacy Files