1. Part I: Mill’s Methods redux
Part II: Analogical Reasoning

2. Homework Informal Fallacies pp. 103-105, §4.1 “Fallacies in General”
pp , §4.3 “Fallacies of Weak Induction”
Review:
Induction
Analogical Reasoning, e.g., ex. 8.4
Causal Argumentation, e.g., 8.3b
Inductive Generalization, e.g., 8.2b

3. Mill’s Methods Agreement Difference (Agreement & Difference)
A causal conclusion is strong to the degree that it is supported by premises with evidence of one or more of Mill’s methods (p. 79)
Mill’s Methods
Agreement
Difference
(Agreement & Difference)
Concomitant Variation
Residue
Typically establishes sufficient conditions
Establishes variable relations
Establishes partial causation

4. Mill's Method: Concomitant Variation
A first discovery: the volume knob
If variations in phenomenon E coincide with variations in phenomenon P, then it is probable that E and P are causally related. (p. 75)

5. Mill’s Methods: Residue
Characteristic features
Deals with complex phenomena
Established knowledge of some causal factors
in measured quantities
Subtract from any phenomenon such part as is known by previous inductions to be the effect of certain antecedents, and the residue (i.e., remaining parts) of the phenomenon is the effect of the remaining antecedents

6. Mill’s Method: Residue
After realizing a loss of $100,000 a department store’s chief accountant could suggest only three causes: an excessive number of clerks, increases in utility rates, and damage to merchandise caused by a flood. These expenses were estimated at $25,000, $30,000 and $10,000 respectively. Since no other ordinary sources could be found, the accountant attributed the remaining $35,000 to shoplifting.

7. Mill's Method: Residue
After realizing a loss of $100,000 a department store’s chief accountant could suggest only three causes: an excessive number of clerks, increases in utility rates, and damage to merchandise caused by a flood. These expenses were estimated at $25,000, $30,000 and $10,000 respectively. Since no other ordinary sources could be found, the accountant attributed the remaining $35,000 to shoplifting.
Is there sufficient evidence for this attribution?
Fallacious: weak induction

8. Induction – Final Unit
Analogical Reasoning

9. Analogical Reasoning Reasoning that depends on a comparison
Typically two things, i.e., events, states of affairs, practices, etc.
Point of Comparison
Common Properties
Inferred Property

10. Analogical Reasoning

11. Factors Affecting Strength
Analogical Reasoning
Factors Affecting Strength
Common features relevantly similar to inferred feature
Number (extent) of these similarities
Diversity among common features
No relevant dissimilarities (disanalogy)

12. Factors Affecting Strength
Analogical Reasoning
Factors Affecting Strength
Relevance of similarities to inferred feature
Causal connection:
I’m allergic to hornet stings. Their venom causes me to swell up and sometimes I come close to losing consciousness. Yellow jackets aren’t as aggressive as hornets, but they’re both stinging bees and have a similar venom. I’ve not been stung by a yellow jacket. Nevertheless, I’ll keep away from it. I’m probably allergic to its sting as well.
Subject: Yellow Jacket stings
Analogue: Hornet stings
Common features: stinging bee, wasp family, venom
Inferred feature: allergic reaction to venom

13. Factors Affecting Strength
Analogical Reasoning
Factors Affecting Strength
Relevance of similarities to inferred feature
Statistical connection:
Large classrooms like Memorial Hall traditionally have attendance rates at less than 50% of total. This is, in fact, especially true of the freshman/sophomore classes, and classes that meet early in the morning. Logic 120, a class typically taken by lower classmen, is also held in a large classroom in the student center early in the morning. I suspect that this class also has a low average attendance as well, likely below 50%.
Subject: classroom in Student Center (attendance)
Analogue: Memorial Hall (attendance)
Common features: frosh/soph class, meeting time
Inferred feature: low attendance

14. Factors Affecting Strength
Analogical Reasoning
Factors Affecting Strength
Relevance of similarities to inferred feature
Aesthetic similarity:
I enjoy Stephen King’s novels. They are quick, easy reads but really gripping horror stories. He’s coming out with a new book, and I think it will be good too.
Subject: Stephen King’s new book
Analogue: his previous novels (horror stories)
Common features: authorship, genre
“quick and easy,” “gripping”
Inferred feature: quality of the work (enjoyment)

15. Factors Affecting Strength
Analogical Reasoning
Factors Affecting Strength
Disanalogies
A dissimilarity between subject and analogue is relevant to the inference
Differences of kind
Feature possessed by analogue but not subject
Though Jones tends to struggle with his class work, he is a good student in art class. His random-abstract learning style seems suited the subject. You know, I just noticed that he has logic right after art class. So I think he’ll do well in logic also.

16. Comparable Entities?
Dog?
My dog

17. Argument
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.

18. Homework Informal Fallacies pp. 103-105, §4.1 “Fallacies in General”
pp , §4.3 “Fallacies of Weak Induction”
Review:
Induction
Analogical Reasoning, e.g., ex. 8.4
Causal Argumentation, e.g., 8.3b
Inductive Generalization, e.g., 8.2b