Fallacy
A fallacy is an argument that is not
logically valid, no matter how appealing
it may be.
Dicto Simpliciter:
Drawing a conclusion from an unqualified
generalization
e.g.
“Exercise is good. Therefore everyone should
exercise.”
“Smoking is bad for your health. Every one
should not smoke.”
Hasty Generalization:
Basing a general conclusion on too few
instances or facts.
e.g.
“Every German I have met is short. The
Germans are a short peoples.”
Post Hoc (Ergo Propter Hoc)
False causality. Because one event occurs
after another, the first event must be the
cause of the second.
e.g.
“If there are black clouds in the south, then it
will rain.”
(diff between empirical & rational)
Contradictory Premises:
A conclusion from two contradictory premises
e.g.
“There are no absolutely true statements.”
“It is impossible for written words to
communicate anything.”
“If God is all powerful, can he put himself out
of existence and come back with twice the
power he had before?”
Ad Misericordiam:
Appeal to pity. Basing a logical argument on
an appeal to someone’s emotions.
e.g.
“You can’t give me a C, I worked so hard!”
False Analogy:
Drawing a conclusion by making a
comparison to something.
e.g.
“Girls are like ice cream. You should taste all
the flavours before you chose a favourite.”
Hypothesis Contrary to Fact:
Drawing a conclusion from a hypothesis that
is not true.
e.g.
“If Madame Curie had not left a
photographic plate in a drawer with a chunk
of pitchblende, the world today would not
have x-ray machines.”
Poisoning the Well (Ad Hominem):
Arguing against someone’s ideas by attacking
the person.
e.g.
“Mr Bush will tell you we are over spent on
education. Naturally we expect that don’t we
because he’s a republican?”
“You may argue that God doesn’t exist, but
that’s just because you are faithless.”
Appeal to authority:
e.g.
“It’s true because my ToK teacher told me.”
“It’s true because they researched it and
proved it.”
False dilemma:
e.g.
“Either you’re with me or against me.”
“Either we cut welfare or we increase taxes,
that’s the way it is.”
Appeal to common practice:
e.g.
“Because that’s the way everyone does it.”
“Why are you picking on me for making
noise, they’re making noise as well.”
Begging the question, circular argument:
e.g.
“God exists because the Bible says that he
does.”
“If she floats, she’s a witch!”
Criticisms of Rationalism
Used by academic elite to discredit common
sense.
It doesn’t actually improve anything.
e.g. should we tell grandma she’s logically wrong about
those black rain clouds?
Cannot study how knowledge is made
using just abstract methods.
e.g. non-verbal knowledge
Logic is a new fashion.
e.g. cultures have traditional respected common sense &
non-verbal skills.
Defence
It is logic’s abstraction that makes it useful,
because it means we can apply one
generalisation to many situations.
e.g.
Scientific laws
We seek guiding principles in science, but we always
remember that the principals are essentially flawed
because they are idealised abstractions of reality.