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“Debate between Christians“ Acre
	1290, _Atlas_des_Croisades_, Jonathan Riley-Smith Ad Ignorantiam
(Argument From
Ignorance) Examples:
Self-Quiz with Answers

Abstract: Ad ignorantiam arguments (the appeal to ignorance) and related fallacy examples are provided and analyzed for credibility in a self-scoring quiz.

Fallacy Practice Directions:

(1) Study the features of the ad ignorantiam from webpage: Ad Ignorantiam (Appeal to Ignorance).

Argumentum ad Ignorantiam (Appeal to Ignorance) Fallacy:

The Ad ignorantiam fallacy is the logical error occurring when a proposition is unjustifiably claimed to be true simply on the basis that it has not been proved false


the logical error occurring when a proposition is unjustifiably claimed to be false simply because it has not been proved true.

(2) Read and analyze the following passages.

(3) Explain with a sentence or two as to whether or not you judge an ad ignorantiam fallacy to be present.

Check your answer.

Ad Ignorantiam Example Exercises

  1. “What happened last week to White House Press Secretary Sarah Huckabee Sanders and her friends at the Red Hen restaurant … [was that her] ideology led to Sanders and her party being expelled from the establishment. A waiter had served their meal, but after learning that Sanders was there, the owner asked her to leave. … Those who claim to be defenders of free speech and free association have been stangely quiet about the incident, leading one to believe they support the restaurant owner's decision.”[1]

    Comment: The ad ignorantiam fallacy occurs. Mr. Thomas argues that since defenders of free speech and free association have not objected to Ms. Sanders' ouster, they must have supported the restaurant owner's decision.
  2. “[T]o reach its secondhand smoke conclusions, the Environmental Protection Agency employed statistical techniques that were grossly dishonest. Some years ago, I had the opportunity to ask a Food and Drug Administration official whether his agency would accept pharmaceutical companies using similar statistical techniques in their drug approval procedures. He just looked at me.”[2]

    Comment: Implicitly, there is an ad ignorantiam appeal. From the fact that a Food and Drug Administration official does not respond to a question, one cannot conclude the official's agreement or disagreement to the point at issue.
  3. ”Opponents of comprehensive sex education in the state, including Christian lobbying groups and other social conservatives, said any deviation from an abstinence-focused curriculum will encourage risky behavior. But there is no scientific evidence to back up that claim. In fact, a 2007 federal study indicated abstinence-only programs had no impact on the rate of teen sexual activity.”[3]

    Comment: The argument is not an ad ignorantiam fallacy since evidence to the contrary of the claim that abstinence-focused curricula encourages risky behavior is provided.
  4. “The Education Endowment Fund (EEF) even published some research findings in 2015 showing that philosophical discussion among pupils led to small improvements in reading and maths performance in primary schools. … Stephen Gorard, one of the academics behind this research, said that perhaps the best we can say from these findings is that philosophy doesn't harm Sats outcomes. The EEF research shows, then, that there are no good reasons not to do philosophy.”[4]

    Comment: Since some evidence is given, the ad ignoratiam fallacy does not occur. Instead the fallacy of ignoratio elenchi (irrelevant conclusion) occurs. The argument is since the EEF research shows philosophical discussion leads to small improvement in reading and math, the EEF research shows there are no good reasons not to do philosophy. From the fact that there is some evidence for a conclusion, it does not logically follow that there is no evidence against that conclusion.
  5. “I would like to see the federal government streamlined, but Thomas G. Donlan was being — at best — facile and premature in saying that the federal operations were shut down ‘without being missed.’ No one knows what harm may have been caused during the shutdown because no one has an instant knowledge of all federal activitiess — what furloughed intelligence analysts may have missed spotting; which Commerce Department export initiatives were damaged; which oil-rig inspection will now prove to be two weeks late, etc.”[5]

    Comment: The ad ignorantiam fallacy occurs in the passage. Initially, it might seem as though the writer is merely making the point that without further information we cannot conclude no harm was done by the federal shutdown. In this he is correct, but he claims that we do not know the harm that was done because we do not yet have knowledge of those federal activities which will prove to be harmful. If there is no information of harm done at the present time, then on the basis of that fact, it is not now known whether there will be or will not be damages occurring as a result of the shutdown without further evidence being presented.
  6. “The wide appeal of the idea that some students will learn better when material is presented visually and that others will learn better when the material is presented verbally, or even in some other way, is evident in the vast number of learning-style tests and teaching guides available for purchase and used in schools. But does scientific research really support the existence of different learning styles, or the hypothesis that people learn better when taught in a way that matches their own unique style?

    Unfortunately, the answer is no, according to a major new report published this month in Psychological Science in the Public Interest … [A]lthough numerous studies have purported to show the existence of different kinds of learners (such as ‘auditory learners’ and ‘visual learners’), those studies have not used the type of randomized research designs that would make their findings credible.”[6]

    Comment: No fallacy occurs. The passage describes new randomized research on a topic that provides better evidence that older non-randomized studies.
  7. “Heeled footwear began to be used more than a 1000 years ago, and led to the occurrence of the first cases of schizophrenia.” …

    “Many data suggest an association between the use of heeled footwear and schizophrenia and they could probably be questioned in many instances. I have however not been able to find any contradictory data. One possibility would be the existence of young patients not being able to use their legs during many years and yet having schizophrenia. I have never seen such a patient. I suggest that there is an association between the use of heeled footwear and schizophrenia.”[7]

    Comment: The fallacy of ad ignorantiam occurs. From the fact the author has not personally observed a patient having a certain characteristic, it does not logically that no such patient exists.
  8. “Statistics go to prove that good years and bad years [for the number of herring off the Scottish coast] run in groups, and the recent series of bad years was almost exactly paralled thirty-two years ago. [I]t has not been proved that our seas have been depleted of food-fishes to a dangerous extent by man … the sea can hold its own even against human cupidity.”[8]

    Comment: Since the author argues from the fact that it has not been proved that the Scottish waters have been over-fished, it follows that the oceans will continue to provide enough fish. Thus, the ad ignorantiam fallacy occurs.
  9. “Such a gigantic will as that of a Buddha or a Jesus could not be obtained in one life, for we know who their fathers were. It is not known that their fathers ever spoke a word for the good of mankind. … If it was only a case of hereditary transmission, how do you account for this petty prince, who was not, perhaps, obeyed by his own servants, producing this son, whom half a world worships? How do you explain the gulf between the carpenter and his son, whom millions of human beings worship as God? It cannot be solved by the theory of heredity.”[9]

    Comment: The fallacy of ad ignorantiam occurs. From the fact that we do not know anything the fathers of Buddha and Jesus spoke, we cannot conclude anything about their character. Also the fallacy of complex question occurs presupposing that necessarily there was “a gulf” between father and son. From the fact that we can't account for something, we cannot form a definite conclusion.
  10. “That Christ could laugh is beyond dispute, for He was a man and risibility his proprium. That He did not laugh we may conclude … from the silence of the gospels. As to why he did not, Jorge believes it is because He recognized that laughter, proprium or not, is inappropriate for those who server God and seek salvation.”[10]

    Comment: The ad ignorantiam fallacy occurs since the author argues that because the New Testament gospels did not record Christ's laughter, Christ never did so.
  11. “National Public Radio reported last month ‘the FBI has conducted more than 100 investigations into suspected Islamic extremists within the military.’ What else would infiltration look like?”[11]

    Comment: From the fact that no results of many investigations are known, one cannot conclude that any of those investigations were successful. Since no substantiation of the investigations was mentioned, one cannot logically conclude that any of the investigations were successful. Some evidence must be presented in order for a conclusion to be drawn. The fallacy of ad ignorantiam occurs.
  12. Consumer Reports has urged the U.S. Food and Drug Administration to develop a standard for allowable levels of arsenic for rice, after its study found traces of the element in rice and rice product samples it tested. It also recommends that adults and children limit their consumption of rice and rice products

    The USA Rice Federation responded quickly to the study, saying rice's reputation as a nutritious, healthy and safe food is well-established. ‘We are aware of concerns about the level of arsenic in food, but are not aware of any established studies directly connecting rice consumption and adverse health effects,’ said Anne Banville, vice president, domestic promotion for the USA Rice Federation.”[12]

    Comment: The argument is implicit that since the USA Rice Federation is not aware of any “well-established” studies showing arsenic in rice is harmful, rice's reputation as a safe food is sustained. Rice consumption might be safe, but this argument does not show that it is. The fallacy of ad ignorantiam occurs.
  13. “Of finite sets in nature may be mentioned the totality of electrons in the universe, or all the stars. It is supposed by at least one reputable authority that these sets are indeed finite, but it has not been proved. That the set of all stars is a discrete set is obvious.”[13]

    Comment: No fallacy is present since there is no argument. Even if it were contextually an argument, it's not contradictory to suppose that a statement can both be obvious and not proved.
  14. “Leading air-safety experts have concluded that the captain of flight MH370 deliberately crashed the plane. … A Canadian air-crash investigator, Larry Vance, said he believed that Captain Zaharie put on an oxygen mask before depressurising the plane to render the passengers and crew unconscious: ‘There is no reason not to believe that the pilot did not depressurise the cabin to incapacitate the passengers.”[14]

    Comment: Captain Zaharie is said to have depressurized the plane on the grounds that there is no reason not to believe he didn't. The fallacy of ad ignorantiam occurs.
  15. “Fifth Amendment Can't Shield Selective Answers”

    “A murder suspect's silence during initial questioning by police can be used against him at trial, the sharply divided Supreme Court ruled Monday. ‘It has long been settled that the privilege “generally is not self-executing” and that a witness who desires its protection “must claim it,”’ according to the lead opinion written by Justice Samuel Alito and joined by Chief Justice John Roberts and Justice Anthony Kennedy.

    Although ‘no ritualistic formula is necessary in order to invoke the privilege … a witness does not do so by simply standing mute,’ Alito added.

    In so ruling, we explained that ‘if [the defendant] believed that his failure to cooperate was privileged, he should have said so at a time when the sentencing court could have determined whether his claim was legitimate,’ the decision states.”[15]

    Comment: The court has ruled that a suspect's silence is evidence that may be used at trial unless the suspect specifically invokes his right not to speak. This is a ruling of the court as to legislative procedure — not an argument. No fallacy occurs.


1. Cal Thomas, “Bigotry Returns to Virginia,” Index-Journal 100 no. 102 (June 28, 2018), 8A.

2. Walter Williams, “Bizarre Arguments and Behavior,” Index-Journal 95 no. 308 (March 27, 2014), 8A.

3. Editor of Herald of Rock Hill S.C. quoted in “Better Sex Education Needed in Our Sate,” Index-Journal 94 no. 360 (April 26, 2013), 8A.

4. Peter Worley, “A School of Thought: Why British Pupils Should Study Philosophy,” The Guardian (June 20, 2018)

5. David Machlowitz, “Mailbag,” Barron's93 no. 44 (November 4, 2012), 46.

6. Association for Psychological Science, “Education: Learning Styles Debunked,” ScienceDaily Association for Psychological Science (December 17, 2009)

7. Jarl Flensmark, “Is There an Association Between the Use of Heeled Footwear and Schizophrenia?” 63 no. 4 Medical Hypotheses, 740-747. doi: 10.1016/j.mehy.2004.05.014

8. Dugald Mitchell, Tarbert in Picture and Story (Falkirk, Scotland: John Calancer, 1908), 117.

9. Swami Vivekananda, Karma-Yoga: The Yoga of Action in The Complete Works fo the Swami Vivekananda, Part I, 2nd. ed. (Almora, Himalayas Advaita Ashram, 1915), 49.

10. Louis MacKey, “The Name of the Book,” SubStance 14 No. 2 Is. 47 (1985), 34. doi: 10.2307/3685049"

11. Cal Thomas, “Suppose Bachman Is Right?” Index-Journal 94 No. 95 (August 2, 2012), 8A.

12. Elton Robinson,"U.S. Rice Industry Responds to Consumer Reports Arsenic Study," Delta Farm Press (Septenber 20, 2012)

13. Eric Temple Bell, The Handmaiden of the Sciences (Baltimore: Williams & Wilkins, 1937), 55.

14. Simon Calder, “MH370 Investigators Say Captain Deliberately Crashed the Plane in Murder-Suicide,” Business Insider May 14, 2018

15. Dan McCue, “Fifth Amendment Can't Shield Selective Answers,” Courthouse News Service (June 17, 2013).

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