A Class Room Logic: Deductive and Inductive, with Special Application to the Science and Art of TeachingMcNair, George Hastings
Philosophy
A Class Room Logic: Deductive and Inductive, with Special Application to the Science and Art of Teaching
McNair, George Hastings
Logic
(4) This would result in two negatives; therefore no conclusion could
be drawn, if the minor premise were negative.
_Problem: To prove that the conclusion must be particular._
_Data_: Given the form of the third figure:
M ― G
M ― S
―――――
S ― G
_Proof_: (1) The minor term, which is the predicate of the affirmative
minor premise, is undistributed; because no affirmative distributes its
predicate.
(2) If undistributed in the premise, then the minor term must remain
undistributed in the conclusion, where it is used as the subject.
(3) The conclusion must, then, be particular; since all universals
distribute their subjects.
_Epitome._
_In the third figure, unless the minor premise be affirmative, there
can be no conclusion; since a negative minor would necessitate a
negative major. An affirmative minor compels a particular conclusion,
in order that the minor term, in the conclusion, may remain
undistributed._
_Canons of the fourth figure._
(1) If the major premise is affirmative, the minor premise must be
universal.
(2) If the minor premise is affirmative, the conclusion must be
particular.
(3) If either premise is negative, the major must be universal.
_Problem: To prove that if the major is affirmative, the minor must be
universal._
_Data_: Given the form of the fourth figure:
G ― M
M ― S
―――――
S ― G
_Proof_: (1) If the major premise is affirmative, then its predicate
which is the middle term, M, is undistributed; for no affirmative
distributes its predicate.
(2) The middle term must then be distributed in the “minor” according
to rule 3.
(3) Then the “minor” must be universal; since only universals
distribute their subjects.
_Problem: To prove that if the minor is affirmative, the conclusion
must be particular._
_Data_: Given the form of the fourth figure:
G ― M
M ― S
―――――
S ― G
_Proof_: (1) If the minor premise be affirmative, then S, its
predicate, must be undistributed; because no affirmative distributes
its predicate.
(2) Since S is undistributed in the minor premise, it must remain
undistributed in the conclusion where it is used as the subject.
_Problem: To prove that if either premise is negative, the major must
be universal._
_Data_: Given the form of the fourth figure:
G ― M
M ― S
―――――
S ― G
_Proof_: (1) If one of the premises is negative, then the conclusion
must be negative according to rule 6.
(2) If the conclusion is negative, then the predicate, G, must be
distributed.
(3) If G is distributed in the conclusion, it must be distributed in
the major premise.
(4) The major premise must be universal; as G is used as its subject,
and only universals distribute their subjects.
_Epitome._
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