Notes

Rules of Categorical Syllogism
Rule #1
FALLACY OF EQUIVOCATION - The middle must always be taken in the same sense.
Ex. Father, party, speaker, mouse, bar
Rule #2
FALLACY OF ILLICIT PROCESS * Illicit Major – The predicate is universal in the conclusion not in the major premise. * Illicit Minor – The subject is universal in the conclusion but not in the minor premise.
Rule #3
FALLACY OF MISPLACED MIDDLE TERM – The middle term should not occur in the conclusion.
A steward is a flight attendant; M + p
But, a steward is a male; M + s
Therefore, a steward is a male flight attendant. M + sp

You are happy; M + p
But, you are energetic; M + s
Therefore, you are happy and energetic. M + ps
Rule #4
FALLACY OF UNDISTRIBUTED MIDDLE TERM – The middle term must be distributed universally, at least once, in the premises.
All stewardesses are female; P + m
But, all mothers are female; S + m
Therefore, all mothers are stewardesses. S + p

All apples are fruits; P + m
But, some fruits are mangoes; m + s
Therefore, some mangoes are apples. s + p
Rule #5
FALLACY OF A NEGATIVE CONCLUSION DRAWN FROM AFFIRMATIVE PREMISES – Two affirmative premises cannot give a negative conclusion.
All stones are hard; M + p
But, some diamonds are stones; s + m
Therefore, some diamonds are not stones. s – p ?
Rule #6
FALLACY OF NEGATIVE PREMISES - From two negative premises, nothing follows.
A chair is not a table; P - M
But, a table is not a pen; M - S
Therefore, a pen is not a chair. S - P ?

No tenor is a soprano; P - M
But, no soprano is a baritone; M - S
Therefore, no baritone is a tenor. S – P ?
Rule #7
From two particular premises, nothing follows. a. If both particular premises are affirmative, then the subjects and predicates are particular.
Some men are gays; p + m
But, some gays are artists; m + s
Therefore,