Lesson 19
Define "logical argument"
A set of statements, one of which appears to be implied or supported by the others
Define "syllogism"
A syllogism is a deductive argument with one conclusion, two premises, and three forms
Determine the mood of this syllogism:
Some Spanish speakers are not Italian speakers
Some French speakers are not Italian speakers
Therefore some French speakers are not Spanish speakers.
IOO
What is the figure of a syllogism?
Placement of the middle term
Define "validity"
A syllogism is valid if and only if the conclusion is necessarily true given that the premises are true.
Identify the conclusion in the following statements:
Some Greek speakers are Latin speakers. Therefore, some Romans are not Greek speakers, because some Romans are not Latin speakers.
Therefore some Romans are not Greek speakers.
What is a major, minor, and middle term?
Major term is the predicate of the conclusion and is used in one premise.
Minor term is the subject of the conclusion and is used in one premise.
Middle term is found once in each premise
All foreigners are aliens
No neighbors are foreigners
Therefore no neighbors are aliens
AEE
Determine mood and figure:
All foreigners are aliens
No neighbors are foreigners
Therefore no neighbors are aliens
AEE-1
Syllogisms are valid or invalid.
Statements are true or false.
What words are conclusions introduced with?
Therefore, thus, so, consequently
Pooh is a bear, and all bears are lovers of honey. So Pooh is a lover of honey.
Major: lover of honey
Minor: Pooh
Middle: bear
EOO
No P is M
Some S is not M
Therefore some S is not P
Determine the mood and figure of this syllogism:
Some Spanish speakers are not Italian speakers
Some French speakers are not Italian speakers
Therefore some French speakers are not Spanish speakers.
IOO-2
A syllogism that is both valid AND has true premises, and therefore a true conclusion.
Since, because, for, given that
The ancient writers were clear writers, and no clear writers are poor teachers. Consequently, some ancient writers are not poor writers.
Major: poor teachers
Minor: ancient writers
Middle: clear writers
AIO
All P is M
Some M is S
Therefore some S is not P
EOO -2
No P is M
Some S is not M
Therefore some S is not P
Identify the conclusion in the following statements:
Some madmen are quiet people and no madmen are poets. It follows that some quiet people are not poets.
Locate the major, minor, and middle terms. Then locate the major and minor premises.
Sam was not the villain, because the villain was a vile man, and Sam is not a vile man.
Major: villain
Minor: Sam
Middle:vile man
Major premise: The villain was a vile man.
Minor premise: Sam is not a vile man.
No P is M
Some M is S
Therefore some S is not P
AIO-4
All P is M
Some M is S
Therefore some S is not P