Flaw III Flashcards
A fallacy that fallacy exists when the arguer decides on what he wants to believe, and then asserts that reality matches that belief.
It often takes the form of an assumption that something is true, and a choice to make no inquiry to check facts.
Its form
Person A has a belief or model in mind pertaining to something.
Person A insists that reality conforms to what he has in mind.
A priori - “from the earlier”
Its form
Person A has a belief or model in mind pertaining to something.
Person A insists that reality conforms to what he has in mind.
Often the arguer, when faced with reality that differs from the belief, deploys other fallacies and strategies to support a priori.
He seeks out evidence to support his belief, which may be flimsy or suspect or mere rumors.
She reinterprets her experiences to support the belief.
He flatly rejects counter-evidence and contrary arguments without analysis.
She praises or rewards people who have spoken in accord with her belief.
He mocks or punishes people who have spoken contrarily e.g. calling them conspriacy theorists or subversives.
Ad Hoc
“From this”
An argument A is offered after the fact to explain an event X, in order to allege that A caused X. However no attempt is made to show that argument A is true or even related to X.
It generally signifies a solution designed for a specific problem or task, non-generalizable, and not intended to be able to be adapted to other purposes.
Its form
Event X occurs.
Unrelated or unsupported Argument A is offered to explain it.
Examples
The lightning was bright and powerful, because the god Thor made it.
Everyone in the town died from the excruciating plague except one girl, because God favored her.
The attacks were perpetrated by foreign terrorists, because no one else could have.
Affirming a Disjunct
This is also known as False exclusionary disjunct.
Two propositions are given and they are independent. When one of them turns out to be true, the arguer claims the other is false.
Its form -Proposition A is independent of Proposition B therefore both can be true or neither or just one. -Proposition A is found to be true. Therefore the arguer claims that -Proposition B is false.
Examples
The baby has red hair, or the baby has web feet. The baby does not have web feet therefore it has red hair.
The voter may be a Republican or the voter may be a Christian. The voter is a Christian therefore we say they are not a Republican.
The truck is blockish looking or the truck is blue or the truck is not running. I know the truck is not running, therefore it’s also not blue and not blockish.
Weaknesses
In this fallacy the arguer is making a mistake of assuming that two propositions are connected when they are not. You should point this out and emphasize that these two things are independent.
The arguer is assuming that an “or” relationship is exclusive rather than inclusive. (See Quick Reference 1.)
A Priori
The a priori, “from the earlier” fallacy exists when the arguer decides on what he wants to believe, and then asserts that reality matches that belief.
It often takes the form of an assumption that something is true, and a choice to make no inquiry to check facts.
Its form
Person A has a belief or model in mind pertaining to something.
Person A insists that reality conforms to what he has in mind.
What flaw
The baby has red hair, or the baby has web feet. The baby does not have web feet therefore it has red hair.
Affirming a Disjunct
This is also known as False exclusionary disjunct.
Two propositions are given and they are independent. When one of them turns out to be true, the arguer claims the other is false.
Its form -Proposition A is independent of Proposition B therefore both can be true or neither or just one. -Proposition A is found to be true. Therefore the arguer claims that -Proposition B is false.
Weaknesses
In this fallacy the arguer is making a mistake of assuming that two propositions are connected when they are not. You should point this out and emphasize that these two things are independent.
The arguer is assuming that an “or” relationship is exclusive rather than inclusive. (See Quick Reference 1.)
Exclusionary Disjunct
Exclusionary Disjunct
One or the other, BUT NOT both
Disjunctive Syllogism
Two kinds:
exclusive (above)
Inclusive - AT LEAST one, MAYBE both
Inference for both
If either P or Q is true and P is false, then Q is true.
Disjunct
Disjunctive Syllogism
Two kinds: inclusive, exclusive
Inclusive Disjunct
AT LEAST one, MAYBE both
Exclusionary Disjunct
One or the other, BUT NOT both
Inference for both
If either P or Q is true and P is false, then Q is true.
Conjunction
In logic a conjunction translates to “and”
This means both conditions are present …in other words
if one is present, the other also must be
“A and B” is true only if A is true and B is true.
Inclusive Disjunct
Inclusive Disjunct
AT LEAST one, MAYBE both
Two kinds of Disjuncts (OR) Inclusive (above) \+ Exclusive Disjunctive One or the other, BUT NOT both
If either P or Q is true and P is false, then Q is true.
Flaw?
Proposition A is believed by the majority of people.
Therefore it is true.
Appeal to Majority
Argumentum ad populum
Flaw?
Proposition P implies Proposition Q.
Therefore Q is deemed to imply P.
Circular Argument
In a circular argument, you have two propositions P and Q, but these are used in a circular fashion as follows:
Its form
Proposition P implies Proposition Q.
Therefore Q is deemed to imply P.
Examples
The bible is the word of the Judeo-Christian god, which says that the god exists, who in turn wrote the bible, which is the word of the god.
Weaknesses
Circular logic is usually presented without evidence to prove either premise.
You can feel justified in asking whether a circular argument is put forth to avoid presenting evidence for the premises.
Flaw?
The bible is the word of the Judeo-Christian god, which says that the god exists, who in turn wrote the bible, which is the word of the god.
Circular Argument
In a circular argument, you have two propositions P and Q, but these are used in a circular fashion as follows:
Its form
Proposition P implies Proposition Q.
Therefore Q is deemed to imply P.
Weaknesses
Circular logic is usually presented without evidence to prove either premise.
You can feel justified in asking whether a circular argument is put forth to avoid presenting evidence for the premises.
Flaw?
All A are members of C.
All B are members of C.
Therefore all A are B.
Syllogistic Fallacy: Undistributed Middle
This is a fallacy involving three sets: A, B and C. It is the assumption that because all A are members of C, and all B are members of C, that all A are B.
Weaknessess
There is usually no reason to believe that two members of a group are identical or related, nor two subgroups of a group.
Example:
A. All cherry tomatoes are red things.
B. All cherries are red things.
C. Therefore all cherry tomatoes are cherries.
Flaw?
A. All cherry tomatoes are red things.
B. All cherries are red things.
C. Therefore all cherry tomatoes are cherries.
Syllogistic Fallacy: Undistributed Middle
This is a fallacy involving three sets: A, B and C. It is the assumption that because all A are members of C, and all B are members of C, that all A are B.
Weaknessess
There is usually no reason to believe that two members of a group are identical or related, nor two subgroups of a group.
Other example
A. Fred is an atheist who lives in California.
B. Ted is also an atheist living in California.
C. Therefore Fed and Ted are actually the same person.
Flaw?
A. Fred is an atheist who lives in California.
B. Ted is also an atheist living in California.
C. Therefore Fed and Ted are actually the same person.
Syllogistic Fallacy: Undistributed Middle
This is a fallacy involving three sets: A, B and C. It is the assumption that because all A are members of C, and all B are members of C, that all A are B.
Weaknessess
There is usually no reason to believe that two members of a group are identical or related, nor two subgroups of a group.
Other example
A. All cherry tomatoes are red things.
B. All cherries are red things.
C. Therefore all cherry tomatoes are cherries.
