ARISTOTLE LOGIC LESSON 1:
(384-322 BC)
3 Sentence Types:
1. Singular: Socrates is a man.
2. Universal: Every man is mortal
3. Particular: Some men are mortal
Objects, Abstract nouns: like walking, and Pronouns: like someone and everyone = Subject (Per Aristotle)
What we say about the Subject = like eating, has fallen: adjectives = is difficult, and nouns = like man in things like "Socrates is man" = Predicate
Aristotle realized that truth of some Subject Predicate sentences has an effect of the truth of other Subject Predicates.
Thus the Square of Oppositions was born.
(1) ALL MEN ARE MORTAL cannot mean (2) ALL MEN ARE NOT MORTAL = CONTRADICTORY
(2) ALL MEN ARE NOT MORTAL cannot mean (3) SOME MEN ARE MORTAL = CONTRACDICTORY
(1) ALL MEN ARE MORTAL plus (3) SOME MEN ARE MORTAL = BOTH CANNOT BE FALSE, BUT BOTH CAN BE TRUE.
(3) SOME MEN ARE MORTAL cannot mean (1) ALL MEN ARE MORTAL = CONTRADICTORY
(2) ALL MEN ARE NOT MORAL cannot mean (4) SOME MEN ARE NOT MORTAL = CONTRADICTORY
*
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SOME MEN ARE MORTAL
(384-322 BC)
3 Sentence Types:
1. Singular: Socrates is a man.
2. Universal: Every man is mortal
3. Particular: Some men are mortal
Objects, Abstract nouns: like walking, and Pronouns: like someone and everyone = Subject (Per Aristotle)
What we say about the Subject = like eating, has fallen: adjectives = is difficult, and nouns = like man in things like "Socrates is man" = Predicate
Aristotle realized that truth of some Subject Predicate sentences has an effect of the truth of other Subject Predicates.
Thus the Square of Oppositions was born.
(1) ALL MEN ARE MORTAL cannot mean (2) ALL MEN ARE NOT MORTAL = CONTRADICTORY
(2) ALL MEN ARE NOT MORTAL cannot mean (3) SOME MEN ARE MORTAL = CONTRACDICTORY
(1) ALL MEN ARE MORTAL plus (3) SOME MEN ARE MORTAL = BOTH CANNOT BE FALSE, BUT BOTH CAN BE TRUE.
(3) SOME MEN ARE MORTAL cannot mean (1) ALL MEN ARE MORTAL = CONTRADICTORY
(2) ALL MEN ARE NOT MORAL cannot mean (4) SOME MEN ARE NOT MORTAL = CONTRADICTORY
*
(
SOME MEN ARE MORTAL