Homework Review Fallacies pp 103105 41 Fallacies in General pp 121131 43 Fallacies of Weak Induction Inductive Argumentation Analogical Reasoning eg ex 84 Causal Argumentation eg 83b ID: 385673
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Slide1
Fallacies - Weak InductionSlide2
Homework
Review:
Fallacies
pp. 103-105, §4.1 “Fallacies in General”
pp. 121-131
, §4.3
“Fallacies of Weak Induction”
Inductive Argumentation
Analogical Reasoning, e.g., ex. 8.4
Causal Argumentation, e.g., 8.3b
Inductive Generalization, e.g., 8.2b
Read for Next Class
pp. 106-116, §4.2 “Fallacies of Relevance”Slide3
Analogical Reasoning
Induction – Final UnitSlide4
AnalysisIdentify Subject and Analogue
Criticism
Are common features relevantly similar to inferred feature?
Is there a
disanalogy
?
Arguments from Analogy?
Both my dog and my neighbor's dog are well-loved members of the family. Each one is well fed, house broken, walked on a regular basis. My dog has a very calm temperament. So I infer that my neighbor's dog also has a calm temperament.Slide5
Weak Induction
Fallacies
TransitionSlide6
Kinds of Fallacies
a defect or error traceable to the very structure (or form) of the argument
a defect which can be detected only by reference to the content of an argument
vs
Form
Content
Formal Fallacies
Informal FallaciesSlide7
Kinds of Informal Fallacies
Fallacies of:
Relevance
Weak Induction
Presumption
Ambiguity
Amphiboly/Equivocation
Whole/Part
See pages 153
f for a complete list
Only required to classify each fallacy according to these four typesSlide8
Your Task on the Exam
Explain how the argument is fallacious.
Fallacies on Exam
fallacy of relevance
fallacy of weak induction
fallacy of presumption
fallacy of ambiguity
none of the aboveSlide9
Weak Induction
FallaciesSlide10
Weak Induction
Inferential connection
evidence not strong enough to support conclusion
Premises
are
relevant to conclusion
Premises do not warrant conclusionSlide11
The Five Fallacies of Weak Induction
Appeal to Ignorance
Appeal to Unqualified Authority
Hasty Generalization
False Cause
Weak Analogy
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusionSlide12
The Five Fallacies of Weak Induction
Appeal to Ignorance
Appeal to Unqualified Authority
Hasty Generalization
False Cause
Weak Analogy
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusion
See earlier presentations for assessment criteriaSlide13
The Five Fallacies of Weak Induction
Appeal to Ignorance
Smoking has not been proven to cause cancer, therefore tobacco products are not carcinogenic
Premises offer only a
lack
of evidence
A definite assertion is made on this basis
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusion
ExceptionsIf search for evidence has been (seemingly) exhaustive by qualified personnelAmerican Legal Standard: “reasonable doubt”
See in-class example:
Mill’s Method of ResidueSlide14
The Five Fallacies of Weak Induction
Appeal to Unqualified Authority
I was speaking to my brother at his auto shop, and he believes the Democrats will lose Maryland in the next election. So I think it’s likely.
Premises offer testimony/opinion from an authority
Conclusion about subject matter is made on this basis
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusion
Question rests on the relevant expertise of the authority consulted
Slide15
The Five Fallacies of Weak Induction
Hasty Generalization
See Presentation “
Induction: Generalizations
”
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusion
Two Issues Affecting Strength
Representativeness of Sample
Interviewer BiasSlide16
The Five Fallacies of Weak Induction
False Cause
Four variants (complex fallacy)
Post hoc ergo propter hoc (“after this, there because of this”)
Non
causa
pro
causa (“non-cause for the cause”)
Oversimplified causeSlippery SlopeSlide17
The Five Fallacies of Weak Induction
False Cause:
After we arrived, the baby got sick. So I think we were the cause of the baby’s illness.
No causal relation apparent or explained
Causal conclusion based on mere temporal succession
“
after this
”
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusionSlide18
The Five Fallacies of Weak Induction
False Cause:
Computer scientists do better at logic. So to do better in this course, you should study computer science
Typically, no assertion of temporal succession
Mistaken assertion of causal agency
“
non-cause
”
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusionSlide19
The Five Fallacies of Weak Induction
False Cause:
Your car is causing global warming.
Phenomenon in question caused by complex number of factors
A single one of these factors is asserted as sole cause
oversimplification
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusionSlide20
The Five Fallacies of Weak Induction
False Cause
:
If you fail this class, then your GPA will go down. If you GPA falls, you’ll lose your scholarship. If you lose your scholarship, you’ll spend all your money on school. If you do this, you’ll have no money for food and shelter. So if you fail this class, you will become a starving, homeless beggar.
A chain of causal events is asserted
The causal connection between some or all events is highly unlikely
At least the ultimate conclusion is highly unlikely
slippery slope
In each case,
The premises are relevant to conclusionPremises provide insufficient evidence to warrant conclusionSlide21
The Five Fallacies of Weak Induction
Weak Analogy
In each case,
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusion
See earlier slides of this presentation!
Two Issues Affecting Strength
Common features relevantly similar to inferred feature
No relevant dissimilarities
(no
disanalogy
)Slide22
Both my dog and my neighbor's dog are well-loved members of the family. Each one is well fed, house broken, walked on a regular basis. My dog has a very calm temperament. So I infer that my neighbor's dog also has a calm temperament.
Arguments from Analogy?Slide23
Fallacies of weak induction
Five identifiable kinds
Not expected to provide the names of these on exam
Fallacies on Exam
In each case:
The premises are relevant to conclusion
Premises provide insufficient evidence to warrant conclusionSlide24
Homework
Review:
Fallacies
pp. 103-105, §4.1 “Fallacies in General”
pp. 121-131, §4.3 “Fallacies of Weak Induction”
Inductive Argumentation
Analogical Reasoning, e.g., ex. 8.4
Causal Argumentation, e.g., 8.3bInductive Generalization, e.g., 8.2b
Read for Next Classpp. 106-116, §4.2 “Fallacies of Relevance”