But, it may be asked, does not the proposition that victories may be
gained by accident rest, as a matter of fact, on the belief that some
victories have been gained in this way? And is not, therefore, the
proper form of proposition Some S is P?
This, however, is a misunderstanding. What we are concerned with is
the formal analysis of propositions as given. And Some victories have
been gained by accident is not the formal analysis of Victories may be
gained by accident. The two propositions do not give the same meaning
in different forms: the meaning as well as the form is different.
The one is a statement of a matter of fact: the other of an inference
founded on it. The full significance of the Modal proper may be stated
thus: In view of the fact that some victories have been gained by
accident, we are entitled to say of any victory, in the absence of
certain knowledge, that it may be one of them.
A general proposition, in short, is a proposition about a genus, taken
universally.
II.--SECOND FIGURE.
For testing arguments from general principles, the First Figure is the
simplest and best form of analysis.
But there is one common class of arguments that fall naturally,
as ordinarily expressed, into the Second Figure, namely, negative
conclusions from the absence of distinctive signs or symptoms, or
necessary conditions.
Thirst, for example, is one of the symptoms of fever: if a patient is
not thirsty, you can conclude at once that his illness is not fever,
and the argument, fully expressed, is in the Second Figure.
All fever-stricken patients are thirsty.
This patient is not thirsty.
[.'.] He is not fever-stricken.
Arguments of this type are extremely common.
Armed with the general principle that ill-doers are ill-dreaders,
we argue from a man's being unsuspicious that he is not guilty.
The negative diagnosis of the physician, as when he argues from the
absence of sore throat or the absence of a white speck in the throat
that the case before him is not one of scarlatina or diphtheria,
follows this type: and from its utility in making such arguments
explicit, the Second Figure may be called the Figure of Negative
Diagnosis.
It is to be observed, however, that the character of the argument is
best disclosed when the Major Premiss is expressed by its Converse by
Contraposition. It is really from the absence of a symptom that the
physician concludes; as, for example: "No patient that has not a sore
throat is suffering from scarlatina". And the argument thus expressed
is in the First Figure. Thus the reduction of Baroko to the First
Figure by contraposition of the Middle is vindicated as a really
useful process. The real Middle is a contrapositive term, and the form
corresponds more closely to the reasoning when the argument is put in
the First Figure.
Public-domain text, read in full here on John Shaqi.
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