Logical fallacies
Fallacious arguments are increasingly common in rhetoric and especially
so on Usenet. Here are some common fallacies to beware.
This list was compiled from various sources, including the New York Public
Library Desk Reference, Webster's Collegiate Dictionary, and the Oxford
English Dictionary.
ARGUMENTUM AD BACULUM (argument backed by a stick)
Resorting to threat.
ARGUMENTUM AD HOMINEM
Pointing out on an irrelevant character defect or
personal circumstance.
ARGUMENTUM AD IGNORANTIAM
Asserting that something is true because it hasn't
been proved false, or vice versa.
ARGUMENTUM AD POPULUM
Appeal to popular opinion, bias, or misconception.
ARGUMENTUM AD VERECUNDIAM (shameful argument)
Using an authority in one
field to back a point in another in which that person is not especially
qualified.
BEGGING THE QUESTION
Assuming the truth of a point raised in a question or
discussion, so that it illogically serves as its own proof.
CIRCULAR REASONING
Using a conclusion as its own premise.
CONSENSUS GENTIUM FALLACY
Appealing to the beliefs or behavior of the majority.
ETYMOLOGICAL FALLACY
Assuming the first appearance of a word is its
correct usage and proper meaning.
EQUIVOCATION
Using an ambiguous word or expression in one sense in a premise
and in another in the conclusion.
FALLACY OF DIVISION
Presuming of the part what is generally true of the whole.
FALLACY OF COMPOSITION
Presuming of the whole what is true of a part.
GAMBLER'S FALLACY
After nine heads, expect tails.
GENETIC FALLACY
Mistakenly reducing something to its origins.
IGNORANTIA ELENCHI (ignorance of conclusion)
Proving a point that
is irrelevant to the issue at hand.
MISSING MIDDLE
"all birds fly; bats are mammals; bats don't fly."
NON SEQUITUR
The premises of the argument do not lead to the conclusion.
PATHETIC FALLACY
Imputing human intent to nature.
POST HOC ERGO PROPTER HOC
Presuming a causal relationship. "Since A came
before B, A caused B."
UNDISTRIBUTED MIDDLE
"all birds fly; bats fly; bats are birds."
Peter Klausler (pmk@sgi.com)