Logical Fallacies (mistaken reasoning/unlikely inferences)
Overgeneralization
Claims which use words like all, never,
most, and seldom not as figures of
speech but as ways of avoiding assessing or questioning the
likeliness of an event which is part of the claim. Ex. Hondas
never get better gas mileage than Volkswagens.
Red Herring
Statements intended to divert attention
from the issue at hand to another, usually less significant,
issue. Ex.You know, even though we disagree on whether to fly or
drive, don't you think the new SUVs are less likely to roll over
than they once were?
Slanting
Statements which emphasize one
part of the evidence (usually the favorable part) and ignore
other parts, averages, and patterns. Ex. In three of the last
six years we have had record snowfalls in the Cascade Mountains.
Global warming is not a problem here.
Post Hoc
The implication that because something came before it was the
cause of what came after. Ex. If I had not stopped to talk to
Nancy, I would not have accidentally unplugged the computer when
I leaned back in my chair.
Association
The implication that because something is where it is, it has the
character of the things around it. Ex. I saw John down by the bus
depot yesterday talking to that school dropout, video freak
Freddy. I didn't think John was like that.
Circular
A claim that contains a character in its premise that it contains
in its conclusion. Ex. Students do not listen to my explanations
because the students are stupid. (Stupidity means knowing better
but choosing not to--it means not listening.)
Bandwagon
A claim that bases its merit not on a direct look at the evidence
but on the popular opinion of the evidence. Ex. If most of the
news journalists are saying the same thing, then we had better
accept their conclusions.
Experts and False
Authority
A claim that bases its merit not on evidence or principle, but on
the fame, notoriety, or political position of a person. This most
difficult bias is only diminished by introducing people to formal
experimental procedures and controlled sampling techniques, and ,
even then, facts and logic will not persuade many who have
already found value in the falsehood. Ex. Republicans will not
let the Bureau of the Census use controlled sampling techniques
to get better estimates of the U.S. population because the
currently undercounted poor are more likely to be Democrats than
the overcounted rich.
Non sequitor
An argument where the conclusion does not follow from the
premises. Ex. All girls have blue eyes; Jill is a girl;
therefore, Jill is going to wear a blue dress to the ball.
Ad hominem
Much like slanting and association, a claim that the theory is
flawed and the evidence is tainted because the experimenter or
observer is flawed or tainted. Ex. Who are you going to believe
that drunk Harry or the Police Officer.
Slippery Slope
The Tragedy of the Commons is a bit of a slippery slope. Is it
true that if we give an inch they will take a mile? If we don't
act now, will all hell break loose. Does Greenspan face all sorts
of slippery slopes when comparing the current use of interest
rates (to control inflation and soften recession) with other
economic periods?
Todd Browne 10/21/98
Rob, I got another example that I learned in my Economics class that
you could use for your list of logical fallacies(an error in reasoning
that usually leads to a incorrect conclusion). My example is a "fallacy
of composition" which may fall under your Bandwagon category, but here
it is anyway. A fallacy of compositon involves reasoning that what is
true of the part(or the individual) is necessarily true of the whole (or
the group). Ex--If I were to stand up at a baseball game, then I'll see
better. Therefore, if everyone were to stand up, then everyone would be
able to see better.