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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)

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Informal Fallacieshttp://ww2.coastal.edu/dearl/PHIL101/Fallacies.html “A Short Catalog of Informal Fallacies”

Evaluation & Critique

fallacies of presumption
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
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
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
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 critique6
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) It says in the Bible that God exists.

(2) The Bible is God’s word.

(3) God never speaks falsely.

(4) Everything in the Bible must be true.

evaluation critique7
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) It says in the Bible that God exists.

(2) The Bible is God’s word.

(3) God never speaks falsely.

(4) Everything in the Bible must be true.

evaluation critique8
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 critique9
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
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 critique11
Evaluation & Critique

Murder is morally wrong. Therefore, abortion is morally wrong.

  • What is the conclusion of this argument?

Therefore, abortion is morally wrong.

evaluation critique12
Evaluation & Critique

Murder is morally wrong. Therefore, abortion is morally wrong.

  • What is the premise?

(1) Murder is morally wrong.

evaluation critique13
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 critique14
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
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 critique16
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 critique17
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
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 critique19
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 critique20
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
Fallacies of Sense
  • where the meaning either of premises or conclusions remains dubious thus clouding the overall argument structure.
    • Equivocation
    • Amphiboly
equivocation
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
equivocation23
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 critique24
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 critique25
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
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 critique27
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
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 critique29
Evaluation & Critique

Composition or Division?

Salt is a nonpoisonous compound. Therefore, sodium and chlorine are nonpoisonous.

Division

evaluation critique30
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 critique31
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 critique32
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.)