Download Informal Fallacies

Informal Fallacies
http://ww2.coastal.edu/dearl/PHIL101/Fallacies.html
“A Short Catalog of Informal Fallacies”
Evaluation & Critique
Fallacies of Presumption

Where premises presume what is to be
proved
–
–
–
–
Begging the Question
Complex Question
False Dichotomy (the “Either…Or…” Fallacy)
Suppressed Evidence
Begging the Question (BQ)

a form of illicit reasoning wherein the illusion
is produced by verbal wordplay that a
conclusion has been proved.
–
–
–
Illicit assumption
Rhetorical rephrasing
Circular Reasoning
BQ: Circular Reasoning

occurs when the truth of the conclusion rests
on premises whose own truth rests on the
truth of the conclusion.
For Example:
It says in the Bible that God exists. Since the
Bible is God’s word, and God never speaks
falsely, then everything in the Bible must be
true. So, God must exist.
Evaluation & Critique
It says in the Bible that God exists. Since the
Bible is God’s word, and God never speaks
falsely, then everything in the Bible must be
true. So, God must exist.

What is the conclusion of this argument?
So, God must exist.
Evaluation & Critique
It says in the Bible that God exists. Since the
Bible is God’s word, and God never speaks
falsely, then everything in the Bible must be
true. So, God must exist.

What are the premises?
(1)
(2)
(3)
(4)
It says in the Bible that God exists.
The Bible is God’s word.
God never speaks falsely.
Everything in the Bible must be true.
Evaluation & Critique

The conclusion is:
So, God must exist.

What is the offending premise, i.e., the
premise or premises that presumes this
conclusion?:
(1)
(2)
(3)
(4)
It says in the Bible that God exists.
The Bible is God’s word.
God never speaks falsely.
Everything in the Bible must be true.
Evaluation & Critique

The conclusion is:
So, God must exist.

The offending premise is:
(3) God never speaks falsely
and to a lesser extent
(2) The Bible is God’s word.
In other words, the premises assert that God exists and
speaks – but not falsely, and the Bible is a record of
this.
Evaluation & Critique

BQ: Circular Reasoning
Definition: occurs when the truth of the conclusion
rests on premises whose own truth rests on the
truth of the conclusion.
Explanation: Only existing beings can speak. If God
speaks - as it says in a premise, then God is
thereby presumed to exist. So the conclusion that
“God must exist” rests on a premise which already
implicitly asserts his existence.
BQ: Illicit Assumption

occurs when a key premise is left unsaid, a
premise whose truth is dubitable or
controversial.
For Example:
Murder is morally wrong. Therefore, abortion is
morally wrong.
Evaluation & Critique
Murder is morally wrong. Therefore, abortion is
morally wrong.

What is the conclusion of this argument?
Therefore, abortion is morally wrong.
Evaluation & Critique
Murder is morally wrong. Therefore, abortion is
morally wrong.

What is the premise?
(1) Murder is morally wrong.
Evaluation & Critique

The conclusion is:
Therefore, abortion is morally wrong.

What is the assumption, the unstated
premise, that presumes this conclusion?:
(*) Abortion is murder.
Evaluation & Critique

BQ: Illicit Assumption
Definition: occurs when a key premise is left unsaid,
a premise whose truth is dubitable or controversial.
Explanation: The arguer assumes that abortion is
murder. This is precisely the statement that
demands proving in order to accept the main
conclusion of the argument, i.e., abortion is morally
wrong.
Complex Question

occurs when a questioner attempts to trap a
respondent by asking a supposedly simple
question which in fact contains two distinct
questions.
For Example:
Where did you hide the drugs you stole?
Evaluation & Critique
Where did you hide the drugs you stole?

What are the two questions (or statements)
implicit in this one question?
(1) Where did you hide the drugs? (or You hid
drugs.)
(2) Did you steal drugs? (or You stole drugs.)
In other words, the very question presumes the
drugs are stolen.
Evaluation & Critique

BQ: Complex Question
Definition: occurs when a questioner attempts to trap
a respondent by asking a supposedly simple
question which in fact contains two distinct
questions.
Explanation: The question is deceptively simple. It
really contains two questions: (1) where are the
drugs and (2) did you steal them. In fact, the
question presumes the drugs are stolen.
False Dichotomy

an illicit form of reasoning in which two
alternatives (in either-or form) are presented
as if their were no other alternatives when, in
fact, other more palatable alternatives likely
exist.
For Example:
If you don’t love America then just get the hell
out.
Evaluation & Critique
False Dichotomy
Definition: an illicit form of reasoning in which two
alternatives (in either-or form) are presented as if
their were no other alternatives when, in fact, other
more palatable alternatives likely exist.
Explanation: ???
If you don’t love America then just get the hell out.
Evaluation & Critique
False Dichotomy
Explanation: The arguer suggests there are only two
alternatives, love America or leave it. By “love
America” I take this to mean “do not criticize her.”
But it is possible to “love America” and to criticize
her in a constructive manner.
If you don’t love America then just get the hell out.
Fallacies of Sense

where the meaning either of premises or
conclusions remains dubious thus clouding
the overall argument structure.
–
–
Equivocation
Amphiboly
Equivocation

where a conclusion depends on a word or
set of words whose meaning is not the same
as that used in the premises.
–
æquus "equal" + vocare "to call“

words or phrases used as if they have the same
meaning in two different contexts where they do not
Equivocation
Some have argued that it’s inappropriate for the press
to investigate the private lives of public officials,
movie stars, members of royal families, and other
celebrities. However, the public has a right to know
what is in the public interest, such as in cases of the
government’s raising taxes, its military expenditures,
etc. The private lives of celebrities are also in the
public interest, and since it’s appropriate to make
known what is in the public interest, it really is
appropriate for the press to investigate the private
lives of celebrities.
Evaluation & Critique
Some have argued that it’s inappropriate for the press
to investigate the private lives of public officials,
movie stars, members of royal families, and other
celebrities. However, the public has a right to know
what is in the (1) public interest, such as in cases of
the government’s raising taxes, its military
expenditures, etc. The private lives of celebrities are
also in the (2) public interest, and since it’s
appropriate to make known what is in the public
interest, it really is appropriate for the press to
investigate the private lives of celebrities.
Evaluation & Critique

Equivocation
Definition: where a conclusion depends on a word or set of
words whose meaning is not the same as that used in the
premises.
Explanation: The phrase “public interest” is used in two distinct
senses. First, “public interest” means the goods and
expenditures common to society collectively, e.g., taxes,
military expenditures, etc. Second, it means the interest of
private individuals about popular subjects, e.g., the interest
by many in the lives of celebrities. The argument treats these
two as equivalent expressions.
Amphiboly

where a syntactically ambiguous premise (e.g., a
mistake of grammar or punctuation) leads to a false
conclusion.
For Example:
A reckless motorist injured a student in his pickup truck
Thursday who was jogging through campus. So kids,
don’t jog in pickup trucks. It’s very unsafe.

Evaluation & Critique

Amphiboly
Definition: where a syntactically ambiguous premise
(e.g., a mistake of grammar or punctuation) leads
to a false conclusion.
Explanation: The phrase “who was jogging through
campus” refers to the injured student. The
conclusion erroneously takes it to refer to the
reckless motorist.
Whole Part Fallacies

where transfer of an attribute is illegitimate
from whole to part or vice versa.
–
Composition: where an attribute of (all) the parts
is erroneously asserted of the whole (i.e., a genus
or a class as a whole).
–
Division: where an attribute of the whole is
erroneously asserted of the part(s)
Evaluation & Critique
Composition or Division?
Salt is a nonpoisonous compound. Therefore,
sodium and chlorine are nonpoisonous.
Division
Evaluation & Critique

Division
Definition: where an attribute of the whole is
erroneously asserted of the part(s) .
Explanation: The attribute of the whole compound,
i.e., that it is “non-poisonous,” is inferred to each
element of the compound. (Each element is
poisonous when isolated.)
Salt is a nonpoisonous compound. Therefore, sodium and chlorine are nonpoisonous.
Evaluation & Critique
The CCU football team should be good next year.
After all, everyone on the team is a good athlete,
so the team as a whole should be good.

Composition
Definition: where an attribute of (all) the parts is erroneously
asserted of the whole (i.e., a genus or a class as a whole).
Explanation: ???
Evaluation & Critique
The CCU football team should be good next year.
After all, everyone on the team is a good athlete,
so the team as a whole should be good.

Composition
Definition: where an attribute of (all) the parts is erroneously
asserted of the whole (i.e., a genus or a class as a whole).
Explanation: The attribute of each member of the team, i.e., that
each is good, is inferred to apply to the whole team. (It may
be the team lacks cohesiveness, so the team may not be
good as a team.)
Evaluate & Critique
If Fallacious
Identify Fallacy
Concrete Explanation