Ignorance is usually dangerous, but when it is clothed with an apparent rationality it is even more so because it mocks our logic and induces us to accept foolish ideas. The argument from ignorance or appeal to ignorance turns ignorance into its battle horse, confuse us and make us accept sharp judgments that aspire to become absolute truths.
One of the most famous examples of the ad ignorantiam fallacy was seen by all: Senator Joseph R. McCarthy’s hearings in the early 1950s. In a series of televised hearings, McCarthy accused many innocent people of being communists , in the midst of an atmosphere of “witch hunts” in which were made unfounded but very damaging accusations.
McCarthy always appeared with a bulky briefcase supposedly full of files with information on the accused persons. But in most cases he did not present – or presented very little – real evidence. In fact, he is said to have had 81 stories of people whom he considered communists, but at one point he said, referring to case 40: “I don’t have much information on this, except for the agency’s general statement that there there’s nothing in the archives to disprove their communist connections”.
McCarthy resorted to an argumentum ad ignorantiam in that case, a Latin expression meaning “appeal to ignorance.” Rather than prove his claim by providing evidence, McCarthy based his accusation on the lack of evidence to refute his claim.
The appeal to ignorance is particularly dangerous because it can persuade people of the most eccentric ideas or launch the most unsuspected accusations, just because no one can prove otherwise.
Unfortunately, this type of argument is widely spread in our daily lives, both in politics and the press and in informal discussions with friends. Learning to detect the argument from ignorance is essential to avoid falling into its networks.
What is the argument from ignorance?
The appeal to ignorance or argumentum ad ignorantiam consists in defending an idea by simply saying that there is no proof to the contrary. In practice, something is assumed to be true or false just because the interlocutor cannot present convincing evidence to the contrary.
It is known as argumentum ad ignorantiam because these people do not base their speech on a more or less deep knowledge about the subject, but precisely on the ignorance that exists about it. It is not based on knowledge but on its absence.
Basically, this fallacy consists in assuming that since X cannot be refuted, then X is true. Although its opposite is also valid, that is, since X cannot be proved, then X is false.
There are many examples of the argument from ignorance. Someone may say that since intelligent life has not been proven outside of Earth, then it does not exist. Or that since cell phones have not been shown to cause cancer, they are completely safe. There are also those who suppose that, if nobody complains about the situation, it is because the situation is satisfactory, inferring that the one who is silent grants, despite the fact that there may be a thousand reasons not to openly express a complaint, such as fear of reprisals.
In fact, the argumentum ad ignorantiam violates systematically the principle of sufficiency, according to which the absence of evidence against a claim does not constitute sufficient proof of its veracity, just as the absence of evidence for a claim is not sufficient proof against it too.
The trap set by the appeal to ignorance
In logic there is the principle onus probandi or burden of proof, according to which, the person who breaks normality is in charge of reliably proving his or her claim. In practice, if someone makes an accusation, he or she must prove it. And if someone pretends to stand up with a new truth or to put something in dispute, must also give evidence to support his or her arguments.
However, the argumentum ad ignorantiam ignores this principle. The person who appeals to ignorance conveniently slips away from that burden to place it on the shoulders of his or her interlocutor. He or she merely launches an idea, often cloaked in pretense of truth, challenging the others to try to prove otherwise, when in fact it is his or her duty to provide valid arguments to support his or her claim.
Thus, the person who resorts to the ad ignorantiam fallacy manages to put us against the ropes, trying to get us to prove or refute his or her claims, since it is the only defense that he or she leaves us. If we do not have sufficient knowledge, it will be difficult for us to make convincing arguments or defend ourselves against the accusations.
In practice, what that person does is demand that we respond with logic and arguments when he or she is unable to follow logic or provide a valid argument. He or she demands a fair play to us, when he or she has already cheated.
How to refute the argumentum ad ignorantiam?
First of all, it is important not to start arguing about the argument in question because that way only increases the chances that the emotions take over and the discussion derail. A fallacy ad ignorantiam shouldn’t be refuted, it must be pointed out and exposed the lack of arguments. Sometimes it is enough to point out that “the absence of proof doesn’t prove anything.”
In fact, the Greek philosopher Sexto Empirico recommended suspending dialogue and any type of judgment when a discussion starts from fallacious premises and there is not enough evidence that can prove or refute an argument. In this way we will avoid falling into the trap of the argumentum ad ignorantiam and getting involved in useless discussions that consume our energy unnecessarily.
After all, life is uncertainty and discovery. There are many issues that cannot yet be categorically refuted or accepted. And we have to learn to live with it. Just as we have to learn to deal with people who launch unfounded accusations with ignorance as a banner.
Vilanova, J. (2011) Petitio principi, ad ignorantiam y fundamentación del conocimiento. Crítica, Revista Hispanoamericana de Filosofía; 43(127): 27–57.
Walton, D. (1999) The Appeal to Ignorance, or Argumentum Ad Ignorantiam. Argumentation; 13(4): 367-377.