12/3/13 Critical thinking web
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[TUTORIAL F01] What is a fallacy
Fallacies are mistakes of reasoning, as opposed to making
mistakes that are of a factualnature. If I counted twenty people in
the room when there were in fact twenty-one, then I madea factual
mistake. On the other hand, if I believe that there are round
squares, I am believingsomething that is inconsistent. This is a
mistake of reasoning, and a fallacy, since I shouldnot have
believed something inconsistent if my reasoning is good.
In some discussion, a fallacy is taken to be an undesirable kind
of argument or inference.For example, a certain textbook explains
"fallacy" as "an unreliable inference". In our view,this definition
of fallacy is rather narrow, since we might want to count certain
mistakes ofreasoning as fallacious even though they are not
presented as arguments. For example,making a contradictory claim
seems to be a case of fallacy, but a single claim is not
anargument. Similarly, putting forward a question with an
inappropriate presupposition mightalso be regarded as a fallacy,
but a question is also not an argument. In both of thesesituations
though, the person is making a mistake of reasoning since he is
doing somethingthat goes against one or more principles of correct
reasoning. This is why we would like todefine fallacies more
broadly as violations of the principles of critical thinking,
whether or notthe mistakes take the form of an argument.
The study of fallacies is an application of the principles of
critical thinking. Being familiar withtypical fallacies can help us
avoid them. We would also be in a position to explain otherpeople's
mistakes. There are different ways of classifying fallacies.
Broadly speaking, wemight divide fallacies into four kinds.
Fallacies of inconsistency: cases where something inconsistent
or self-defeating has been proposed or accepted.Fallacies of
inappropriate presumption: cases where we have an assumptionor a
question presupposing something that is not reasonable to accept
inthe relevant conversational context.Fallacies of relevance: cases
where irrelevant reasons are being invoked orrelevant reasons being
ignored.Fallacies of insufficiency: cases where the evidence
supporting a conclusionis insufficient or weak.
We shall discuss these fallacies in the next few tutorials.
