Reduced to the categorical:
A M
Vertebrates must have G
a backbone (Co-extensive),
E This S
animal is not a M
vertebrate,
E ∴ This S
animal cannot have G
a backbone.
As co-extensive A’s distribute their predicates the possibility of there being a fallacy of illicit major is forestalled.
Categorically considered the argument is likewise valid.
8. DISJUNCTIVE ARGUMENTS.
It has been observed that a disjunctive proposition is one which expresses an alternative. A disjunctive syllogism is one in which the major premise is a disjunctive proposition.
ILLUSTRATION:
The boy is either honest or dishonest,