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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.

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

(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.

(4) Check your answer.

1. “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 paralleled 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.”[1]
   
   

   Answer
   
   
   
   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.
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]
   
   

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   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 does not have the basis to conclude confidently the official's agreement or disagreement to the point at issue. The official could have had many different reasons for lack of responding to the question.
3. ”Opponents of comprehensive sex education in the state … 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]
   
   

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   Comment: The argument is not an ad ignorantiam fallacy since evidence that comprehensive sex education does not encourage risky behavior is provided and that evidence confutes the Christian lobby's presumption that any deviation from abstinence-focused curricula encourages risky behavior.
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 [Standard Assessment Test] outcomes. The EEF research shows, then, that there are no good reasons not to do philosophy.”[4]
   
   

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   Comment: Since some evidence is given for the conclusion that there are no good reasons not to do philosophy, the ad ignoratiam fallacy does not occur.
   
   Nevertheless, the fallacy of ignoratio elenchi (irrelevant conclusion) could be claimed to occur since one of the conclusions drawn by the researcher does not logically follow. The insubstantial argument stated by the researcher can be summarized as follows:

   EEF research shows classroom philosophical discussion leads to small improvements in reading and math.
   

   ---

   ∴ The best we can conclude is that philosophical discussion does not harm assessment scores.

   From the fact that there is some good evidence for doing philosophy, namely that it improves assessment reading and math scores, it does not logically follow that there are no good reasons not to do philosophy.
5. “Thomas G. Donlan was … premature in saying that the federal [government's] 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 activities [such as] 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]
   
   

   Answer
   
   
   
   Comment: Initially we might think the ad ignorantiam fallacy occurs in this argument because the writer seems to claim that we cannot know the harm done until we can learn the damages resulting from the government shutdown.
   
   However, closer reading indicates the writer claims we cannot know at the time of the government shutdown what the consequences will be in the future. The writer does point out that there might be resultant damage, but since there is insufficient information known at the time of the shutdown, we cannot know for sure whether or not there are damages occurring in future weeks. Consequently, the ad ignorantiam fallacy does not occur.
   
   It's worth noting that Donlan's assessment in the first sentence that nothing was amiss as a result of the shutdown is an implicit ad ignorantiam since this conclusion was drawn before the effects of the shutdown could be known.

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]
   
   

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   Comment: No fallacy occurs. The passage describes new randomized research on a topic that provides better evidence than 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. … 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]
   
   

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   Comment: If the the writer were to assert rather than suggest that heeled footwear and schizophrenia are associated, then the fallacy of ad ignorantiam would occur. 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. “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]fter 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 strangely quiet about the incident, leading one to believe they support the restaurant owner's decision.”[8]
   
   

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   Comment: The ad ignorantiam fallacy occurs. The writer mistakenly argues that since defenders of free speech and free association did not object to Ms. Sanders' ouster, they must have supported the restaurant owner's decision. From the fact that the defenders of free speech were silent, no conclusion can be validly drawn as to the support of the manager's action.
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]
   
   

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   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.

    close ×

    Proprium:

    A characteristic not essential to a species but is unique and conventional to it. For example, human beings have the characteristic of laughter.

    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]
    
    

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    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]
    
    

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    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]
    
    

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    Comment: For the ad ignorantiam fallacy to occur, the USA Rice Federation would have had to conclude that rice's reputation as a safe food is assured in light of the fact that no “well-established” studies have shown arsenic in rice is harmful. The Federation does not claim that rice consumption has been proven safe; they claim only that they are not aware of any studies showing rice is not safe.
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]
    
    

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    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]
    
    

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    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 [of being protected from self-incrimination]“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 [of the Fifth Amendment] … 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]

    
    
    

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    Comment: As to the presence of a fallacy, this passage is somewhat deceptive. 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.

Notes