An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

240 THE GENERAL NATURE OF INDUCTION.
on the truth of the major premise. The enthymeme in
fig. i. differs from the scientific syllogism (o-vX\.oyio-/bib<;
eTTio-T rjiJLOviKos) in fig. i., only through having as middle
term the symptom or effect, not the cause or ground.
The following examples will make the difference clear :
Ex. i. Enthymeme in fig. i.
All such combinations of symptoms mean Consump
tion
Here we have such a combination ;
Therefore this is a case of Consumption.
The physician s diagnosis would run thus ; and the
middle term the combination of characteristic symp
toms does not express the cause, but the effect,
of the disease. But in a treatise on the subject, he
would begin by describing the specific microbe or
bacillus and the effects of its introduction into the
human organism :
"When bacillus x is introduced, such
and such things follow; here it is introduced; observe
the consequences." And when this argument is ex
pressed formally as a syllogism,
it would run thus :
Ex. 2. Scientific syllogism in fig. i.
If bacillus x is introduced, such and such things
follow ;
This is a case of the introduction of the bacillus ;
Therefore the results in question must follow.
And observation shows that the results do follow.
When expressed categorically, the syllogism has, as
its middle term, "the introduction of the bacillus"
i.e., the cause of the disease.
We may also sum up
the result of the discussion
as to the connection of smoke and rain, in the form
of an enthymeme in fig.
i. :