The Green caldron - University Library

March, 1962 ,
TO
President Kennedy Is a
Republican—Valid
Judith Landesman
Rhetoric 102, Theme 4
9
UNDERSTAND THE SYLLOGISM, ONE MUST FIRST UN-
derstand what the primary background of the syllogism is. Man answers
questions by means of logic. He reasons his problems out by three different
methods : analogy, induction, and deduction. Analogy is defined in Form and
Thought in Prose as "a. comparison between two things together with the
argument that, if they are alike in several ways, they are probably alike in
another." Induction is a method of reasoning which takes a number of
particular happenings or truths and shows them to be leading to a general truth.
This is the method used in experimental science. Deduction is a method of
reasoning which takes a general truth and derives from it certain particular
truths.
The syllogism is a form of deductive reasoning. It consists of three
propositions: the major premise, the minor premise, and the conclusion.
Each proposition consists of two terms dealing with classes of things. To
reach a conclusion, naturally, each of these terms is used twice. The first
proposition (normally, the major premise) introduces two of the terms, e.g..
People who live in Urbana are people living in the State of Illinois. The second
proposition (in customary usage, the minor premise) repeats one of the
terms and adds the third, e.g.. Those people living in the State of Illinois are
people who live in the United States. The third proposition omits the term
which has been repeated and forms the other two terms into what is called
the conclusion, e.g.. People who live in Urbana are people who live in the
United States.
One can easily see that the introduction of a fourth term will completely
obliterate the logic of the syllogism. For example, the syllogism:
All girls are good-looking creatures.
Tony Perkins is a young man.
Tony Perkins is a good-looking creature.
Now, Tony Perkins might be a good-looking creature, but this deduction
cannot be satisfactory as far as the logic is this particular syllogism is con-
cerned because of the addition of the fourth term. If the term all girls in the
first proposition were changed to all young men, the syllogism would be
logically correct.
Sometimes, because of a mistake in the definition of terms, one word or