ll not be called upon to prove so simple a proposition as
the one given, but with more difficult ones the method of reasoning is the
same. The process which applies a general proposition (_A_) to a specific
instance (_C_), is called deductive reasoning.

+178. Relation between Inductive and Deductive Reasoning.+--Deductive
reasoning is shorter and seems more convincing than inductive reasoning,
for if the premises are true and the statement is made in correct form,
the conclusions are irresistible. Each conclusion carries with it,
however, the weakness of the premises on which it is based, and as these
premises are general principles that have been themselves established by
inductive reasoning, the conclusions of deductive reasoning can be no more
_sure_ than those of inductive reasoning. Each may prove only that the
proposition is probably true rather than that it is surely true, though in
many cases this probability becomes almost a certainty.

+179. The Enthymeme.+--We seldom need to state our argument in the
syllogistic form. One of the premises is usually omitted, and we pass
directly from one premise to the conclusion. If we say, "Henry will not
succeed as an engineer," and when asked why he will not, we reply,
"Because he is not good in mathematics," we have omitted the premise, "A
knowledge of mathematics is necessary for success in engineering." A
shortened syllogism, that is, a syllogism with one premise omitted, is
called an enthymeme.

Thus in ordinary matters our thought turns at once to the conclusion in
connection with but one premise. We make a thousand statements which a
moment's thought will show that we believe because we believe some
unexpressed general principle. If I should say of my dog, "Fido will die
sometime," no sensible person would doubt the truth of the statement. If
asked to prove it, I would say, "Because he is a dog, and all dogs die
sometime." Thus I apply to a specific proposition, Fido will die, the
general one, All dogs die, a proposition about which there is no doubt.

Frequently the suppressed premise is not so well established as in this
case, and the belief or nonbelief of the proposition will be determined by
the individuals addressed, each in accordance with his experience. Suppose
that in reading we find the statement, "A boy of fourteen ought not to be
allowed to choose his own subjects of study, because he will choose all
the easy ones and avoid the more difficult thou