False Dilemma




Also Known as: Black & White Thinking


A False Dilemma is a fallacy in which two options are presented as if they are the only two options and since one is claimed to be false, the other must be true. This fallacy occurs when there are more than two options. This fallacy has the following pattern of reasoning:


Premise 1: Either claim X or Y is true (when X and Y could both be false).

Premise 2: Claim Y is false.

Conclusion: Therefore, claim X is true.


This is fallacious because if both claims could be false, then it cannot be inferred that one is true because the other is false. That this is the case is made clear by the following example:


Premise 1: Either 1+1 =4 or 1+1=12.

Premise 2: It is not the case that 1+1 = 4.

Conclusion: Therefore 1+1 =12.


While this fallacy can be self-inflicted, it can also be used against others. When used this way, a common tactic is to ensure that one of the options is appealing or implausible to the target of the fallacy. This can be done using various rhetorical techniques, such as hyperbole, or other fallacies, such as Straw Man.

In cases in which the two options are the only two options, this line of reasoning is not fallacious. For example:


Premise 1: Bill is dead or alive.

Premise 2: Bill is not dead.

Conclusion: Therefore, Bill is alive.


A variant of the False Dilemma is the Perfectionist Fallacy. In this case, the false dilemma is between something being perfect or rejecting it. Since perfection is not possible, it is concluded that the thing must be rejected. It has the following form:


Premise 1: X must be perfect, or it must be rejected (when there are other options).

Premise 2: X is not perfect.

Conclusion: Therefore, X must be rejected.


A person might honestly believe that perfection or other unreasonably high standard is required and commit this fallacy in good faith. But the fallacy is usually used as a bad faith argument to reject something. In such cases, the person committing the fallacy knows they are intentionally requiring an unreasonably high standard and are hoping the fallacy will go undetected. This is a form of False Dilemma because it occurs when there are other viable options beyond perfection (or unreasonably high standards) or nothing.

It is not a fallacy to require that something meet reasonable standards or be rejected. There can be good-faith debates about what counts as a reasonable standard, so merely having high standards does not entail that this fallacy has been committed. For example, while a hospital administrator should not expect a perfect backup power system, it would be reasonable for them to expect a reliable system that could power the hospital for an adequate amount of time. How reliable and how long-lasting the system must be can certainly be debated.

Another variant is the Line Drawing Fallacy (sometimes known as the Sorites Fallacy). In this fallacy, it is claimed that unless a precise line can be specified between two things, there is no line or difference between the two. The fallacy can be presented in this manner:


Premise 1: An exact line between X and Y must be drawable or there is no distinction between X and Y (when no such line must be drawn).

Premise 2: An exact line cannot be drawn between X and Y.

Conclusion: Therefore, there is no distinction between X and Y.


This is a form of the False Dilemma fallacy because it erroneously presents the target with two choices that are not the only two options. In this case, one option is drawing a precise line and the other is that there is no distinction.

When I first learned about this fallacy as an undergraduate, the examples were mostly academic constructs. For example, if you pull hair from a person’s head one at a time, you cannot specify the exact number of hairs you must remove before the person is bald. Therefore, you can never make a person bald by pulling out their hair. As another example, if you give a person one dollar at a time, you cannot specify the exact number of dollars you must give them before the person is rich. Therefore, you can never make a person rich by giving them one dollar at a time.

In 1990, however, this fallacy featured prominently in the trial of the officers who beat Rodney King providing the first example I knew that showed this fallacy can have serious consequences. The reasoning used by the jury can be presented as follows:


Premise 1: The first time King was struck was not excessive force.

Premise 2:  If excessive force was used during the beating, then there must be a specific strike at which point the force went from warranted to excessive.

Premise 3: This strike cannot be identified.

Conclusion: The force used in the beating did not become excessive.


While it is (probably) true that the exact point of transition cannot be determined, this is not necessary to determine that it eventually became excessive.


Defense: To avoid inflicting this fallacy on yourself, pause to check to see if you have considered all the (reasonable) options. If someone else is trying to inflict this fallacy on you, take the time to consider whether they have offered all the (reasonable) options. Since those who intentionally use this fallacy will often try to make the option they want you to reject look bad, it is also a good idea to look for the use of other rhetorical devices (such as hyperbole) and other fallacies (such as Straw Man).


Example #1:

Senator Jill: “We’ll have to cut education funding this year.”

Senator Bill” “Why?”

Senator Jill: “Well, either we cut the social programs, or we live with a huge deficit, and we can’t live with the deficit.”


Example #2:

Bill: “Jill and I both support having prayer in public schools.”

Jill: “Hey, I never said that!”

Bill: “You’re not an atheist are you, Jill?


Example #3:

“Look, you are going to have to make up your mind. Either you decide that you can afford this stereo, or you decide you are going to do without music for a while.”

Originally appeared on A Philosopher’s Blog Read More