Complete Definition and the Classification of Fallacy

Definition and the classification of fallacy;

Definition and the classification of fallacy....

A fallacy is a type of argument that may seem to be correct but that proves, on examination, not to be so.  From the foregoing, it is clear that “a fallacy has two features: first, it is an argument; second, its premises provide no support to the conclusion though they appear to do so, because the argument is psychologically persuasive”. There are ‘Formal’ and ‘Informal’ fallacies.

  • Formal fallacies are the types of mistakes we make in our attempt to construct syllogisms (deductive reasoning/a logical argument with two premises and a conclusion) or in using logical reasoning.
  • Informal fallacies, on the other hand, are the types of errors in reasoning that occur as a result of carelessness or inattention to the content of the propositions.

Complete Classification of Fallacy

In this article, we shall focus on Informal Fallacy which can be classified into three broad categories, namely,

  1. fallacies of relevance,
  2. fallacies of ambiguity, and
  3. fallacies of presumption.

Fallacies of Relevance

These are fallacies whose premises appear to be relevant to the conclusion drawn but, on close examination, are simply not relevant. The following below are fallacy under this category:

The Appeal to Force (argumentum ad baculum)

This fallacy is committed when one resorts to the use of threat to cause the acceptance of a conclusion, especially when evidence or rational methods fail.In other words, this fallacy is committed when an argument relies on the threat of force, though the threat may be veiled and not necessarily be physical. For instance, I’ll be committing this fallacy if I threatento fail students who disagree with my political ideologies. This means that the fallacy can be committed by someone in a position of power if he uses threat to coerce his opponents to accept his proffered proposition. The following are examples of arguments that commit this fallacy:

  • All fresh students in the Department of Philosophy should attend my wedding if they want me to be lenient in assessing their exam
  • If you do not agree with my political opinions, you will not graduate from this university.

The Appeal to Pity (argumentum ad misericordiam)

Literally, misericordiam means “a pitying heart”. Thus, this fallacy occurs when the premises of an argument plainly relies on mercy, generosity, altruism, and so on. For instance, a lawyer might use the special circumstances of his client (an offender) to justify leniency in punishment. In short, when the lawyer emphasizes the unfortunate consequences that will befall his client instead of looking at the overwhelming proof of his guilt, he has committed this fallacy. The following passages commit this fallacy:

  • I am a single parent, solely responsible for the financial support of my children. If you give me this traffic ticket, I will lose my license and be unable to drive to work. If I cannot work, my children and I will become homeless and may starve to death. Therefore, you should not give me this traffic ticket (Offor 2012: 42).
  • I implore the jury to temper justice by mercy. Though my client, barely eighteen, is accused of killing his mother and father with an axe, I plead for leniency on the grounds that he is an orphan.

The Appeal to Emotion (argumentum ad populum)

This fallacy is committed when, instead of using evidence and rational argument, you appeal to the emotion of the people to win their assent to a conclusion. The appeal to emotion, therefore, relies on expressive language and other devices to arouse strong feelings that may lead an audience to accept its conclusion. This fallacy is a device often used by politicians, propagandists, is common in commercial advertising. The following example explains this fallacy:

  • The wisest men and women in Yoruba history have all been interested in Ifa. Obas, queens and regents of all epochs in Yoruba land have believed in it and have guided the affairs of their people by it. Therefore those who say that Ifa is not a science are mistaken.
  • In the last presidential campaign, a mammoth crowd welcomed Goodluck Jonathan in each of the northern zones. In the last election, he led the other presidential candidates with very wide margins and became president. Therefore, those who accuse Jonathan of financial misappropriation are not sincere.

The Appeal to Inappropriate Authority (argumentum ad verecundiam)

This fallacy arises when we appeal to the opinions of someone who in fact does not have any legitimate claim to authority in the matter at hand. In other words, it “involves the mistaken supposition that there is some connection between the truth of a proposition and some feature of the person who asserts or denies it For instance, it would be  fallacious to appeal to the opinions of a movie star on whether taking a brand of beer is good for the body or not. Someone with expertise in food nutrition would be the appropriate authority. Thus, “when the truth of some proposition is asserted on the basis of the authority of one who has no special competence in that sphere, the appeal to inappropriate authority is the fallacy committed Consider these examples:

  • Philip Ogundeji, a Professor of Linguistics and African Languages at the University of Ibadan, believes that the stars revolve around the earth in a perfect circle. Therefore, the stars revolve round the earth in a perfect
  • But can you doubt that air has weight when you  have the clear testimony of Aristotle affirming that all the elements have weight including air, and excepting onlyfire?

Argument Against the Man or Person (argumentum ad hominem)

This is a fallacy in which the argument relies on an attack against the person taking a position. In other words, when the thrust of an argument is directed at someone who is defending a conclusion in dispute (and not the conclusion itself), the fallacy committed id ad hominem. There are two major forms of the argument ad hominem, namely, the ‘abusive’ and the ‘circumstantial’. The ‘abusive’ variety of ad hominem is committed when one attacks the person who made an assertion, instead of giving reasons why the assertion should not be accepted. The ‘circumstantial’ occurs when one argues against the circumstance of the opponent, instead of assessing the dispute in question. Consider the following examples:


  • Brown’s arguments for premarital sex should be dropped because he is a womanizer.
  • Darwin’s thesis of natural selection should be discarded as a work of fiction because he is a


  • Father John should accept my position that abortion should be abolished because this is compatible with his faith as a Catholic.
  • Former President Bush wouldn’t approve of President Obama’s economic policies because he is a Republican.

Appeal To Ignorance (argumentum ad ignorantiam)

This fallacy is committed when one posits that a proposition is true simply because it has not been proved false or that it is false because it has not been proved true. Bello  adds that “this mode of argument is commonly used to against the existence of witches, spirits, and other forms of extraordinary’ phenomena”. The following passages commit this fallacy:

  • No one has conclusively proven that there is no intelligent life on the moons of Jupiter. Therefore, there is intelligent life on the moons of Jupiter.
  • The alarmists have not succeeded in proving that the toxic and radioactive materials dumped at Koko (Delta state) are dangerously harmful to human life. The materials are therefore perfectly safe.

Irrelevant Conclusion (ignoratio elenchi)

Ignoratio elenchi translates to “mistaken proof” and is a type of fallacy in which the premises provide justification or grounds for a different conclusion than the one that is proposed. It tries to establish the truth of a proposition with premises which actually provide support for an entirely different conclusion. The following are examples of this fallacy:

  • The Golden rule is basic to every system of ethics ever devised. Everyone accepts it in some form or other. Therefore, people’s lives are guided by legislations.
  • Capitalism is desirable. For at one time all utilities were state-owned; now more and more of them are being commercialised or privatised. The Structural Adjustment Programme (SAP), moreover, is based on capitalist principles. We are well on our way to full-blown capitalism and its complete triumph is inevitable (Bello 2007: 51).

Black-or-White Fallacy

Also referred to as Fallacy of False Alternatives, this fallacy is committed when it is falsely assumed in an argument that only two alternatives or positions are possible in regards to a certain issue or when the possibility of a third alternative to the two already allowed is ignored. For example:

  • He who is not a PDP member is against Jonathan’s regime

Oshiomole is not a PDP member

He is therefore against Jonathan’s regime.

  • He who does not preach the Word of God is an anti- Christ

Bisala does not preach the Word of God Therefore, he is an anti-Christ.

Fallacies of Ambiguity

These fallacies arise “from the equivocal use of words or phrases in the premises or in the conclusion of an argument”. This means that, in fallacies of ambiguity, an important term may have  two or more distinct meanings. Thus when we notice a shift or confusion of meanings within an argument, a fallacy of ambiguity is committed. Let discuss some of them: 

Fallacy of Equivocation

This fallacy is committed when two or more meanings of a word or phrase are used in different parts of an argument. Since most words have more than one literal meaning, we often consider the contexts in which they are used to differentiate those meanings. However, we often confuse the meanings of a word or phrase and when this occurs we are guilty of using the word equivocally, thereby committing the fallacy of equivocation. An equivocation, therefore, “trades upon the use of an ambiguous word or phrase in one of its meanings in one of the propositions of an argument and also in another of its meanings in a second proposition” (Offor). The following are examples of this fallacy:

Only man is rational No woman is a man

Therefore, no woman is rational (Offor).

The word ‘man’ in the argument above is used in different senses in the two premises of the argument, showing no link between the terms of the conclusion.

Andrew has faith in the president He also has faith in telepathy

Therefore, Andrew has faith in both the president and science.

In the above argument the word “faith” is used unequivocally in the two premises. In the first premise, the word “faith” is used by Andrew to assert his confidence that the president will do good work during his tenure; in the second premise, however, Andrew is not saying that he has confidence in telepathy but, rather, saying that he believes that some people are capable of using telepathy as an extra-sensory activity. Therefore, there is no link between the use of the term “faith” in the two premises and the conclusion.

Fallacy of Division

This is a fallacy in which “a mistaken inference is drawn from the attributes of a whole to the attributes of the parts of the whole” Copi et al (2006: 391). There are two varieties of this fallacy and they occur: (1) when you argue fallaciously that what is true of a whole must also be true of its part; (2) when you argue from the attributes of a collection of elements to the attributes of the elements themselves. An example of the first kind of this fallacy is:

Nigeria is a rich and great country. Danladi is a Nigerian.

Therefore, Danladi is rich and great.

An example of the second variety of this fallacy is:

University students study law, physics, commerce, social work and philosophy

Therefore, each university student studies law, physics, commerce, social work and philosophy.

Fallacy of Composition

This fallacy is the reverse of the fallacy of division and it occurs when an inference is mistakenly drawn from the attributes of the parts of a whole to the attributes of the whole. Thus, it “involves an inference from the attribution of some features of every individual member of a class, to the possession of the same feature by the entire class. For example, you commit this fallacy when you argue that:

  • Every part of the new war plane is light in weight Therefore, the new war plane is light in
  • Each departmental library in the university is worth a million dollars

Therefore, the university library is worth a million dollars.

Fallacy of Accent

The fallacy of accent is committed when “a phrase is used to convey two different meanings within an argument, and the difference is based on changes in emphasis given to words within the phrase. In other words, this fallacy occurs when there is a shift of meaning within an argument arising from changes in the emphasis given to its words or parts. Thus, “the way in which the meaning shifts in the fallacy of accent depends upon which parts of it may be emphasized or accented. For example:

Alice was happy and friendly today Therefore, Alice usually is sad and unfriendly.

Obey will win the Olympic championship!

Therefore, Obey has won several other championships except the Olympic championship.

In each of the two examples above, the stress or emphasis on certain words (that is, the accented part) in the premise shifts or changes the meaning of the argument.

Fallacy of Amphiboly

The word “amphiboly” connotes an ambiguity of expression due to grammatical construction. The fallacy of amphiboly occurs, therefore, when we argue from premises whose formulations are ambiguous because of their grammatical construction. It is a fallacy “in which a loose or awkward combination of words can be interpreted more than one way; the argument contains a premise based on one interpretation while the conclusion relies on a different interpretation. This implies that a statement may be true on one interpretation and false on another. The argument becomes fallacious “When such a statement is stated as a premise on the interpretation that makes it true and a conclusion is drawn from it on the interpretation that makes it false. For example:

The philanthropist donated, along with his ex-wife, Jane, two million Naira to the university

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