PHL 3305 Lecture 19

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Altered Schedule:

• Wed 2019-10-16
  • no class
• Fri 2019-10-18
  • exercises through ch 12 due
  • Read LT 13-14
  • exam available 17:00
• Mon 2019-10-21
  • Ch 13 exercises due
  • Start 3rd act
    1. Prior Analytics I1
    2. LT ch 15
• Tue 2019-10-22
  • Study session 19:00 at 2014 Tawakoni Dr
• Fri 2019-10-25
  • exam due by 17:00

Chapter 10, Continued

Four types of propositions

1. Universal affirmation: every B is A [A]
2. Particular affirmation: some B is A [I]
3. Universal negation: no B is A [E]
4. Particular negation: some B is not A [O]

Chapter 11: Supposition and Distribution in Propositions

Supposition

1. proper supposition is the use of the word as a subject to stand literally for what it signifies in relation to the predicate

   e.g., a lamb is an animal

   • improper supposition is a metaphor

     e.g., the Lamb of God takes away the sins of the world

   • personal supposition is the normal way words stand as subjects

     e.g., man is an animal, where man refers to the universal and individuals of that nature.

2. simple supposition stands for what it immediately signifies
3. material supposition

Distribution of Subjects and Predicates

A universal name is distributed when the name stands for all of the individuals under it

• Every universal proposition distributes the subject
• Every particular proposition has an undistributed subject
• Every negative proposition distributes the predicate
• Every affirmative proposition has an undistributed predicate

Chapter 12: Opposition and Obversion of Propositions

Opposition

opposition is the affirmation and negation of the same predicate in regard to the same subject

1. contradictory opposition. propositions are opposed in both quantity and quality
   • if one is true, then the other must be false (complete opposition in truth and falsity)
2. contrary opposition. propositions are opposed in quality only
   • if one is true, the other may not be necessarily true (opposition in truth only)
3. sub-contrary opposition.
   • (opposition in falsity only)

Square of opposition

Rules of Truth and Falsity

1. Contradictory propositions cannot both be true at the same time or false at the same time
2. Contrary propositions cannot both be true at the same time
3. Sub-contrary propositions cannot both be false at the same time
4. Among subalternates
   • when the universal is true, the particular is true (instantiation)
   • when the particular is false, the universal is false (counterexample)
5. "descend with truth, ascend with falsity"

Truth Table

$A$	$E$	$I$	$O$
T	F	T	F
F	?	?	T
F	T	F	T
?	F	T	?
?	F	T	?
F	T	F	T
F	?	?	T
T	F	T	F

Obversion

1. change quality of proposition
2. negate the predicate

Summary

Underlined terms are distributed.

	affirmation undistributed predicate	negation distributed predicate
universal distributed subject	Every A is B (A)	No A is B (E)
particular undistributed subject	Some A is B (I)	Some A is not B (O)