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

OR SCIENTIFIC METHOD. 301
In this work we do not propose to touch on these
subjects.
(2) By the aid of the Double Method of Agreement,
or Difference, we may make the suggested connection
of S and P more reliable, establishing it as a law of
nature.
The first step in real explanation
is to raise this
question : Is there anything in S which is already
known to be capable of producing P, or vice versa 1
This is to connect SP with previous knowledge, by
Analogy.
12. Analogy may be regarded first as a special
kind of argument, as Aristotle does. We have already
discussed it from this point of view (ch. VIII. 3).
The student will remember that Analogy is
"any
resemblance between things which enables us to believe
of one what we know of the other," and that the value
of the inference depends on whether the resemblance
is in the material or essential points and the difference
in the unessential points. We now proceed to discuss
the value of Analogy as a means of suggesting hypo
theses of explanation. At what point does an argu
ment from Analogy pass into a suggested explanation ?
In analogical inference, a new case is shown to be
probably an instance of a cause whose working is
known to be illustrated in a case with which we are
familiar. It is, as Aristotle said, an argument from
particular to particular (&>? /xe/ao? 7r/?o? /zepo?), from
one example (TrapdSeLy/jia) or instance to another,
depending
on the resemblance between the two cases
in some material circumstance. Hence it has been
said that Analogy as long as it remains Analogy only
"sticks in the particular instances"; it does not
work out a law of connection between the two cases,