Epistemology and Logic 25(d) Premises: The first two statements in a syllogism, the
major premise containing the major term, the minor premise
containing the minor term.
(e) Conclusion: The final statement in the syllogism. It
draws an inference based upon the two premises— and,
when valid, justified by them.
(f) Four forms o f statement: To understand how state
ments work in the categorical syllogism, we must consider
two special aspects: quality and quantity.
In the context of deductive logic, quality concerns whether
a statement is affirmative or negative. The statement “Bessie
is a cow” is affirmative; it affirms that Bessie is a cow. The
statement “No cats are cows” is negative; it denies that cats
are cows.
In the context of deductive logic, quantity concerns whether
a statement is universal or particular. The statement “All
cows are females” is universal; it refers to all of its subject
class— all cows. The statement “Some birds are robins” is
particular; it refers to only part of its subject class— some
birds.
These aspects make possible four forms of statement,
designated by the symbols as A, E, I, O:
“A” form: the universal-affirmative (All x is y)
“E” form: the universal-negative (No x is y)
“I” form: the particular-affirmative (Some x is y)
“O” form: the particular-negative (Some x is not y)These four forms of statement may be combined in
several patterns to produce a syllogism - as long as their
combination does not produce any violation of the rules of
validity.
(g) Distribution: The “all” or “some” aspect of a term.
Terms refer to classes of things; but when a term appears in
a statement, it may refer to all members of a class or only to
some members of the class. A term that refers to all members
of its class is a distributed term; a term that refers only to
some members of its class is an undistributed term. It is
helpful to know the pattern of distribution of terms in the
four forms of categorical statement: