False dilemma

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Even crazier than golf, though, is modern American politics, where, thanks to TV and for the convenience of TV, you can only be one of two kinds of human beings, either a liberal or a conservative.
Kurt VonnegutWikipedia[1]

A false dilemma (also known as a false dichotomy) is a logical fallacy which involves presenting two opposing views, options, or outcomes in such a way that they seem to be the only possibilities: that is, if one is true, the other must be false, or, more typically, if you do not accept one, then the other must be accepted. The reality in most cases is that there are many in-between or other alternative options, not just two mutually exclusive ones.

In other words, there are two ways in which one can commit a false dilemma. First, one can assume that there are only two (or three, though in that case it is, strictly speaking, a "false trilemma") options when there really are many more. Second, one can take the options to be mutually exclusive when they really are not.

The fallacy is a syllogistic fallacy and a formal fallacy.

Alternate names[edit]

  • black-or-white
  • denying a conjunct
  • disjunctive syllogism
  • either/or fallacy
  • excluded middle
  • fallacy of exhaustive hypotheses
  • false dichotomy
  • no middle ground
  • rathering


You commit this fallacy if you interpret the negation of a conjunction (e.g. "not both A and B") as implying that at least one conjunct (either A or B) must be true.

P1: Not (A and B)
P2: Not A
C: Therefore, B

In other words, confusing a contradiction (where one or the other must be true, but not both) with a contrary (where both could be false, but both cannot be true).

For example:

P1: Evolution and creationism can't both be true.
P2: Evolution is not true.
C: Therefore, creationism is true.

The above example is fallacious, as it is possible for both creationism and evolution to be untrue (life suddenly appeared one day) or true (god created evolution).


Assuming only two options[edit]

As an example of the first, here is Reed Heustis’s attempt to prove that the Founding Fathers were deeply influenced by John Calvin:

By default, when one rejects Calvin's presupposition, he necessarily adopts that of Karl Marx. Author of the Communist Manifesto, Marx presupposed that Man is inherently good, and that all of Man's problems are the result of a bad environment.[2]

Since the founding fathers were clearly not Marxists, they must have been Calvinists. The rest of us may be inclined to think that, surely, there are more options here (and especially given Marxism is separated from Calvinism by centuries) than presented.

Assuming mutual exclusion[edit]

It is very simple. If I am wrong, they are right. Thus I should be doing the opposite of what I was doing, as that will be the right thing to do. I do not need to think about it. I do not need to introduce complexity where there is none.

As an example of the second, here is Joel Richardson, in the WND, criticizing Ron Paul's foreign policies:

According to Paul, radical Muslims are not radical because they have drunk deeply from the trough of an expansionist, racist and murderous ideology, but rather because American actions abroad have brought about the natural response of resistance.[4]

But of course, adopting one causal factor does not – despite what Richardson assumes – entail rejecting the other (though of course Richardson's caricatures are also strawmen, even regarding an ideologue like Paul).

It is worth noting that it is not a false dilemma to present two options out of many if no conclusion is drawn based on their exclusivity: "you can have tea or coffee" is not a false dilemma; a fallacious form would require it to be presented as an argument such as "you don't want tea, therefore you must want coffee." Though even this is not necessarily a false dilemma if those are the only two options and it has been established that "you" want a drink.


Daniel Dennett coined the term rathering as a "way of sliding you swiftly and gently past a false dichotomy".[5] It was inspired by Stephen Jay Gould's usage of the word rather; Dennett provides an example (emphases added):

Change does not usually occur by imperceptibly gradual alteration of entire species, but rather by isolation of small populations and their geological instantaneous transformation into new species

Of course, both statements can be true.

Some ratherings don't use the word rather, but (for example) not:

Nervous systems need to be seen as actively generating probes of their environment, not as mere computers activating passively on inputs fed to them by sense organs.

Not all usages of the word rather are a false dilemma (or rathering), rather it is a useful technique to detect (possible) false dilemmas.

Alternative Advance[edit]

This is a term coined by Dr Bo Bennett of Logically Fallacious fame, to refer to a false dilemma in which two options, essentially the same but with different wording, are present to the subject.[6] They would be committing fallacious reasoning if they accepted the options as the only ones in existence, because, given more thought, there are in fact other choices. For example, a salesperson asking a potential client if they would rather be contacted by telephone or e-mail. This is alternative advance, since another option would be to not be contacted at all (and I would strongly encourage this). Alternative advance creates a lose-lose situation in which the subject, whatever they do, remains in the thrall of the speaker.


Spotted in the wild:


  • One of the most common false dilemmas espoused by creationists, especially in the United States, is that if there is any flaw at all in the theories of evolution, then creation science is the only other possible truth. (Not even mainstream Christians accepting theistic evolution is acceptable.)
  • This same kind of wooish reasoning is employed, albeit less frequently, by many pseudoscience promoters, taking the form of "since science has not perfectly explained phenomena X yet, my pet goat claim must be true." The obvious rebuttal to this false dilemma is that the science only needs to be tweaked (or explored more) in order to provide an explanation. Even if it can't provide an answer to everything immediately, of course, that is not proof of the "alternate" claim.
  • Many supporters of alternative medicine will claim that one must choose between "allopathy" and whatever magic potions the particular individual happens to believe in. Often, this is accompanied with claims that all scientific studies are rigged and can't be trusted; if the science on which evidence-based medicine is based is false, then the anecdotal evidence behind homeopathy (or whatever) must be good! The trouble with this is that of the hundreds of different and all anecdotally supported alternative therapies, theories, and diets, many are contradictory and cannot possibly all work. Even if the results of all medical studies were made up, that does not somehow make the anecdotes in favor of all the totally contradictory ideas of alternative medicine valid. In the words of Ben Goldacre, "pharma being shit does not mean magic beans cure cancer".[7]
  • Many hereditarians will accuse you of being a Lysenkoist, or believing that humans are born as a "blank slate" if you don't believe that IQ and race are correlated


  • "America — Love It Or Leave It" is a popular false dilemma. The dilemma suggests that a "true patriot" must embrace everything ever done by America, or become un-American. However, since America as a nation was founded on the concept of respectful political dissent, one must doubt the premise of this false dilemma very seriously.
  • Many (but not all!) "if you're for A, you're against B"-statements are a false dilemma. President George W. Bush’s famous statement "Either you are with us, or you are with the terrorists."[8] is a good example. Believing that some measures taken by the Dubya (or Obama, or any other) government were unnecessary, excessive, or morally suspect obviously doesn't entail a murderous disregard for human life — quite the opposite, in many cases. However, if such a statement is backed with a threat of action ("either you support us, or you're our enemy"), it is not a false dilemma, since the speaker is the one who decides who their enemy is.
  • A false dichotomy similar to the last two surrounds discussions about Israel. One example of this is how some persons insist that being critical of the state of Israel or Israeli policies amounts to a) anti-Zionism and b) anti-Semitism. Another example is how persons both on the "pro-Palestinian side" and the "pro-Israeli side" claim that you cannot both support Israel's right to exist and Israel's right to self-defense and also support an independent Palestine or criticize Israeli policies towards the Palestinians.[9] Similarly, you cannot dislike Hamas and Benjamin Netanyahu at the same time.
    • Ted Cruz (R-TX) said, after being booed and heckled during an appearance at a Defense of Christians unity dinner celebrating Christians facing persecution in the Middle East, "If you will not stand with Israel, then I will not stand with you," then walked off the stage in a petulant frenzy.[10] This could also be seen as a form of argumentum ad baculum.
  • Some anti-abortionists present a dilemma between "life begins at conception" and "life begins at birth", taking a denial of the latter to imply support for the former.
  • Texas governor Rick Perry issued a debate challenge to House Minority Leader Nancy Pelosi during his 2012 GOP presidential candidate campaign, despite the fact that Pelosi wasn't running and is a Democrat. Performing poorly in debates against other GOP candidates, he asked Pelosi to debate his own plan to reformat Washington, D.C. versus (his version of) the status quo — and if she refused, declined or did not respond, he told her that "I will take it to mean you will continue your obstructionist ways in the face of much needed Washington reform." Pelosi reportedly laughed at the request and declined, saying she was unavailable to debate due to a busy schedule.[11]
  • The entire two-party system in America is a false dilemma, where it is often assumed that liberal and conservative are the only two political beliefs, often ignoring other views such as leftism. And that's not to mention that "conservative" and "liberal" aren't even mutually exclusive terms to begin with.



See also[edit]

Want to read this in another language?[edit]

Lang-fa.gif دوراهی_اشتباهی in Persian

External links[edit]


  1. Cold Turkey by Kurt Vonnegut (May 10, 2004) In These Times.
  2. Article published in Worldview Weekend in 2009; it does not seem to be available at their website, but here is a discussion on Dispatches from the Culture Wars.
  3. User talk:LANCBUser/Archive2#Vandal bin.
  4. Here be wingnuts
  5. Intuition pumps and other tools for thinking, Danniel C. Dennett, page 48-49
  6. https://www.logicallyfallacious.com/logicalfallacies/Alternative-Advance
  7. http://twitter.com/bengoldacre/status/15857117862
  8. Can be seen here.
  9. As memorably illustrated by Jon Stewart
  10. Cruz booed off stage, CNN
  11. Failing miserably in GOP debates, Perry challenges Pelosi instead, The Raw Story
  12. Lucas!