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Slide 1
Fallacies - Weak Induction
Slide 2
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
Slide 3
ANALOGICAL REASONING Induction Final Unit
Slide 4
Analysis Identify Subject and Analogue Criticism 1.Are common
features relevantly similar to inferred feature? 2.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.
Slide 5
WEAK INDUCTION Fallacies Transition
Slide 6
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 vsFormContent
Formal FallaciesInformal Fallacies
Slide 7
Kinds of Informal Fallacies Fallacies of: 1.Relevance 2.Weak
Induction 3.Presumption 4.Ambiguity a.Amphiboly/Equivocation
b.Whole/Part See pages 153f for a complete list Only required to
classify each fallacy according to these four types
Slide 8
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 above
Slide 9
WEAK INDUCTION Fallacies
Slide 10
Weak Induction Inferential connection evidence not strong
enough to support conclusion Premises are relevant to conclusion
Premises do not warrant conclusion
Slide 11
The Five Fallacies of Weak Induction 1.Appeal to Ignorance
2.Appeal to Unqualified Authority 3.Hasty Generalization 4.False
Cause 5.Weak Analogy In each case, 1.The premises are relevant to
conclusion 2.Premises provide insufficient evidence to warrant
conclusion In each case, 1.The premises are relevant to conclusion
2.Premises provide insufficient evidence to warrant conclusion
Slide 12
The Five Fallacies of Weak Induction 1.Appeal to Ignorance
2.Appeal to Unqualified Authority 3.Hasty Generalization 4.False
Cause 5.Weak Analogy In each case, 1.The premises are relevant to
conclusion 2.Premises provide insufficient evidence to warrant
conclusion In each case, 1.The premises are relevant to conclusion
2.Premises provide insufficient evidence to warrant conclusion See
earlier presentations for assessment criteria
Slide 13
The Five Fallacies of Weak Induction 1.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,
1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion In each case, 1.The
premises are relevant to conclusion 2.Premises provide insufficient
evidence to warrant conclusion Exceptions 1.If search for evidence
has been (seemingly) exhaustive by qualified personnel 2.American
Legal Standard: reasonable doubt Exceptions 1.If search for
evidence has been (seemingly) exhaustive by qualified personnel
2.American Legal Standard: reasonable doubt See in-class example:
Mills Method of Residue
Slide 14
The Five Fallacies of Weak Induction 2.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 its likely. Premises offer testimony/opinion from an
authority Conclusion about subject matter is made on this basis In
each case, 1.The premises are relevant to conclusion 2.Premises
provide insufficient evidence to warrant conclusion In each case,
1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion Question rests on the
relevant expertise of the authority consulted
Slide 15
The Five Fallacies of Weak Induction 3.Hasty Generalization See
Presentation Induction: GeneralizationsInduction: Generalizations
In each case, 1.The premises are relevant to conclusion 2.Premises
provide insufficient evidence to warrant conclusion In each case,
1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion Two Issues Affecting
Strength Representativeness of Sample Interviewer Bias Two Issues
Affecting Strength Representativeness of Sample Interviewer
Bias
Slide 16
The Five Fallacies of Weak Induction 4.False Cause Four
variants (complex fallacy) a.Post hoc ergo propter hoc (after this,
there because of this) b.Non causa pro causa (non-cause for the
cause) c.Oversimplified cause d.Slippery Slope
Slide 17
The Five Fallacies of Weak Induction 4.False Cause: After we
arrived, the baby got sick. So I think we were the cause of the
babys illness. No causal relation apparent or explained Causal
conclusion based on mere temporal succession after this In each
case, 1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion In each case, 1.The
premises are relevant to conclusion 2.Premises provide insufficient
evidence to warrant conclusion
Slide 18
The Five Fallacies of Weak Induction 4.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, 1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion In each case, 1.The
premises are relevant to conclusion 2.Premises provide insufficient
evidence to warrant conclusion
Slide 19
The Five Fallacies of Weak Induction 4.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, 1.The premises are relevant
to conclusion 2.Premises provide insufficient evidence to warrant
conclusion In each case, 1.The premises are relevant to conclusion
2.Premises provide insufficient evidence to warrant conclusion
Slide 20
The Five Fallacies of Weak Induction 4.False Cause: If you fail
this class, then your GPA will go down. If you GPA falls, youll
lose your scholarship. If you lose your scholarship, youll spend
all your money on school. If you do this, youll 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, 1.The premises are relevant to conclusion 2.Premises
provide insufficient evidence to warrant conclusion In each case,
1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion
Slide 21
The Five Fallacies of Weak Induction 5.Weak Analogy In each
case, 1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion In each case, 1.The
premises are relevant to conclusion 2.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) Two Issues Affecting Strength Common features
relevantly similar to inferred feature No relevant dissimilarities
(no disanalogy)
Slide 22
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?
Slide 23
Fallacies of weak induction Five identifiable kinds Not
expected to provide the names of these on exam Fallacies on Exam In
each case: 1.The premises are relevant to conclusion 2.Premises
provide insufficient evidence to warrant conclusion In each case:
1.The premises are relevant to conclusion 2.Premises provide
insufficient evidence to warrant conclusion
Slide 24
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