Philosophy 103 - Introduction to Logic: Critical Thinking

2/9 - Informal Fallacies III
a.k.a Revenge of the Fallacy; Son Of Fallacy, Bride of Fallacy etc.


1. Begging the Question:

This can occur in several different forms. Essentially, this fallacy occurs when the key premise of an argument is unsupported. Here are some varieties of this common fallacy:

Circular reasoning: Murders have lost the right to live because anyone who takes the like of another person has given up that right.

Concealed Premise: Murder is always wrong. Therefore, the death penalty is wrong. (The concealed premise: The death penalty is murder).

Wishful Thinking: Of course there is life after death; if I didn't believe that, life would be too depressing.



2. Complex Question:

Sometimes called a "loaded question". A question which contains a hidden assumption or condition. Often, complex questions are such that no matter how you answer them, you may be acknowledging something you might not want to acknowledge.

Examples: When did you stop lying to your friends? When are you going to give up being a Nazi?

3. False Dichotomy or False Dilemma:

Presents as a premise two alternatives as if they were the only two available when in fact there are more. Often the conclusion is only implied and not stated.

Example: Either we elect Mr. X or the economy goes down the tubes. The choice should be obvious.

The way to avoid falling into this trap: before you accept X because Y is false, make sure there isn't some other alternative that allows you to reject X as well.

4. Suppressed Evidence:

An inductive argument which ignores overriding evidence which would prove a different conclusion.

This is common is advertising. Example: Rent-to-own: the cheaper way to buy!

Quoting out of context can also lead to this fallacy, as can ignoring current events.

5. Equivocation:

Where the conclusion of the argument depends on the fact that a word is being used in two different senses due too semantic ambiguity.

Example: Everyone wants to do what is right. Therefore, you have the right to do what you want.

A sentence is ambiguous when it has two or more meanings (note: ambiguity and vagueness are two different things. Vague means imprecise). Semantic ambiguity is the result of one word having two or more definitions.

Example: The banks were important to the town.

6. Amphiboly:

Where the conclusion of the argument depends on the fact that a sentence is syntactically ambiguous.

Example: Norris said he operates a small car repair shop. Therefore, you can't take your Cadillac to him. This can be a real problem in legal documents.

A sentence is syntactically ambiguous when the grammar of the sentence allows for more than one interpretation of its meaning.

Example: John attacked the man with a knife.

7. Composition:

Mistaking properties of the parts for properties of the whole.

Example: Every member of the team is a winner; therefore the team is a winner.

Not every instance of this type of reasoning is bad however.

Example: Each one of these stamps is valuable. Therefore, the collection of stamps as a whole is valuable.

Here is another example:

by Chris Browne

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8. Division:

Mistaking properties of the whole for properties of the parts.

Example: This wooden table is made up of smaller things called atoms. Since the table is wooden, its atoms must be wooden too. Or: This team is the best in the conference; therefore each team member must be the best in the conference.

Again, not every instance of this reasoning is bad. Pay attention to the context and the details.