Fallacies of Validity

Fallacies of Validity: Summary Sheet

I. Simple Fallacies of Validity

1. Appeal to Pity: Attempt to get the listener to accept the conclusion out of pity, instead of accepting it because it follows validly from the premises.

Example: Surely I can't be guilty of tax evasion, Your Honor; for if I'm found guilty, I'll lose my job, my wife won't get the life-saving operation she needs, and my children will starve.

2. Appeal to Force: Attempt to get the listener to accept the conclusion out of fear of force, instead of accepting it because it follows validly from the premises.

Example: I must be the best-looking logic teacher in the country, since if you disagree with me I'll punch you in the eye, slash your tires, and gives you an 'F'.

3. Appeal to the People: Attempt to get the listener to accept the conclusion simply because it is a widely held view, instead of accepting it because it follows validly from the premises.

Ancient Example: Practically everyone believes the Earth is flat. Therefore, the Earth is flat.

II. Semantic Fallacies of Validity
1. Equivocation: An argument which relies essentially on using a term in two different places, with a different (definitional) meaning in each case.

Example: All EIU students are Panthers. All Panthers are furry. Therefore, all EIU students are furry.

2. Amphiboly: An argument which relies essentially on an ambiguity in meaning stemming from grammatical structure (rather than from a difference in definitional meanings, like in Equivocation).
Example: The President is giving a lecture on student drug abuse in the Lecture Hall at 3 PM. So there must be a significant amount of student drug abuse going on in the Lecture Hall at 3 PM.

III. Counterargument Fallacies of Validity

1. Argument Against the Person: Criticizing an argument simply by finding fault with the person who made the argument (for being bad, hypocritical, or self-interested) instead of finding fauly with the argument itself (for being invalid or having a false premise).

Example: Poet Allen Ginsburg has argued for the abolishment of all censorship of pornography. But you know, Ginsburg is a marijuana-smoking homosexual, and a thoroughgoing advocate of the drug culture; so obviously his argument is no good.

2. Straw Person Argument: Criticizing an argument by finding fault with some other (but similar) argument, instead of the one under discussion.

Example: Rex has argued against obligatory prayer in the schools. Obviously Rex is advocating atheism. But atheist countries suprress all religion, and have state-enforced thought control. Is this what we want for America? Surely not! So Rex's conclusion is completely wrong.

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