1. FALLACIES
Formal fallacies are errors of reasoning by virtue of their forms. Informal fallacies are errors encountered in ordinary
discourse and, sometimes described as fallacies of language. Fallacies may be created unintentionally, or they may be
created intentionally in order to deceive other people. Sometimes the term “fallacy” is used even more broadly to
indicate any false belief or cause of a false belief.
Fallacies of Ambiguity (Unclear Meaning)
1. Fallacy of equivocation. Equivocation is the illegitimate switching of the meaning of a term during the reasoning.
This is also called fallacy of four terms.
Example: God is love, but love is blind, therefore, God is blind.
2. Fallacy of accent. The accent fallacy is a fallacy of ambiguity due to the different ways a word is emphasized or
accented.
Example: “Woman, without her, man is lost.”
3. Fallacy of amphiboly. This is an error due to taking a grammatically ambiguous phrase in two different ways
during the reasoning.
Example: Lost : The dog of a lady with a long tail.
4. Fallacy of composition. The composition fallacy occurs when someone mistakenly assumes that a characteristic
of some or all the individuals in a group is also a characteristic of the group itself, the group “composed” of
those members.
Example: Jose is an intelligent boy
But Jose studies at Lyceum
Therefore, all who study at Lyceum are intelligent
5. Fallacy of division. Merely because a group as a whole has a characteristic, it often doesn’t follow that
individuals in the group have that characteristic. If you suppose that it does follow, when it doesn’t, you commit
the fallacy of division.
Example: The jigsaw puzzle when assembled is circular in shape. Therefore, each piece is circular in
shape.
Fallacies of relevance (Irrelevant Premise or conclusion)
1. Argumentum ad baculum (appeal to force or the threat of force). If you suppose that terrorizing your opponent
is giving him a reason for believing that you are correct, then you are using a scare tactic and reasoning
fallaciously.
Example: You have to be good to us, or else you will fail the student’s evaluation.
2. Argumentum ad misericordiam (appeal to pity or emotions). You commit the fallacy of appeal to emotions when
someone’s appeal to you to accept their claim is accepted merely because the appeal arouses your feelings of
anger, fear, grief, love, outrage, pity, pride, sexuality, sympathy, relief, and so forth.
Example: You have to give me a passing mark, or else you’ll ruin my future.
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2. 3. Argumentum ad populum (appeal to the people). If you suggest too strongly that someone’s claim or argument
is correct simply because it’s what most everyone believes, then you’ve committed the fallacy of appeal to the
people. Similarly, if you suggest too strongly that someone’s claim or argument is mistaken simply because it’s
not what most everyone believes, then you’ve also committed the fallacy. Agreement with popular opinion is
not necessarily a reliable sign of truth, and deviation from popular opinion is not necessarily a reliable sign of
error, but if you assume it is and do so with enthusiasm, then you’re guilty of committing this fallacy.
Example: You should tune in to ABS-CBN, because it’s the most watched station this year.
4. Argumentum ad hominem (argument against the person). You commit this fallacy if you make an irrelevant
attack on the arguer and suggest that this attack undermines the argument itself.
Example: He should not be entrusted with the position, because he’s from a family of drug addicts.
Fallacies of Presumption (Premise Assumed)
1. Fallacy of Accident. This fallacy presumes that a general rule can apply to all situations without due regard to
their accidental features.
Example: Brown is a color, a Filipino is brown, therefore, a Filipino is a color.
2. Fallacy of petition percipii. This means “begging the question.” A form of circular reasoning in which a conclusion
is derived from premises that presuppose the conclusion.
Example: Expert says that Joseph Estarda is the best president of the country,
Those experts are those who maintain that Joseph Estrada is the best president.
3. Fallacy of complex question. You commit this fallacy when you frame a question so that some controversial
presupposition is made by the wording of the question.
Example: “Have you stopped smoking marijuana?”
Fallacies of Indefinite Induction (Insufficient Samples)
1. Fallacy of false cause. Improperly concluding that one thing is a cause of another.
Example: He met an accident because he saw a black cat.
2. Fallacy of converse accident. If we reason by paying too much attention to exceptions to the rule, and generalize
on the exceptions, we commit this fallacy. This fallacy is the converse of the accident fallacy. It is a kind of Hasty
Generalization, by generalizing too quickly from a peculiar case.
Example: Some foreigners are pedophiles, therefore, all foreigners are pedophiles
3. Argumentum ad verecundiam (appeal to inappropriate authority). This fallacy is committed when one cites an
authority in support of one’s argument but this authority is misplaced.
Example: Aswangs exist because our grandparents have always believed in their existence.
4. Argumentum ad ignoratiam (appeal to ignorance). This appears when one appeals to ignorance to win a case.
The fallacy of appeal to ignorance comes in two forms: (1) Not knowing that a certain statement is true is taken
to be a proof that it is false. (2) Not knowing that a statement is false is taken to be a proof that it is true. The
fallacy occurs in cases where absence of evidence is not good enough evidence of absence. The fallacy uses an
unjustified attempt to shift the burden of proof.
Example: Nobody has ever proved that God exists, therefore, God does not exist,
Dowden, Bradley. 2010. Fallacies. Available at http://www.iep.utm.edu/fallacy. Accessed last July 4, 2010
Gripaldo, Rolando M. 2008. Logic and Logical Theory. Included in The Philosophical Landscape 5th Edition. Quezon City : C&E Publishing.
Hurley, Patrick J. 2000. A Concise Introduction to Logic. Belmont, CA : Wadworth / Thompson Learning.

3. Timbreza, Florentino T. 1992. Logic Made Simple. Quezon City : Phoenix Publishing House Inc.
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