he uses are
understood, and that the identities involved in their meanings will be
recognised. And to this question, for the sake of consistency, one of
two answers is required; failing which, there remains the rule of thumb.
First, it may be held that no terms are understood except those that are
defined in expounding the science, such as 'genus' and 'species,'
'connotation' and 'denotation.' But very few Logicians observe this
limitation; few would hesitate to substitute 'not wise' for 'foolish.'
Yet by what right? Malvolio being foolish, to prove that he is not-wise,
we may construct the following syllogism:

_Foolish is not-wise;
Malvolio is foolish;
.'. Malvolio is not-wise._

Is this necessary? Why not?

Secondly, it may be held that all terms may be assumed as understood
unless a definition is challenged. This principle will justify the
substitution of 'not-wise' for 'foolish'; but it will also legitimate
the above cases (concerning 'human life' and 'Socrates') as immediate
inferences, with innumerable others that might be based upon the
doctrine of relative terms: for example, _The hunter missed his aim_:
therefore, _The prey escaped_. And from this principle it will further
follow that all apparent syllogisms, having one premise a verbal
proposition, are immediate inferences (_cf._ chap. ix. Sec. 4).

Closely connected with such cases as the above are those mentioned by
Archbishop Thomson as "Immediate Inferences by added Determinants"
(_Laws of Thought_, Sec. 87). He takes the case: '_A negro is a
fellow-creature_: therefore, _A negro in suffering is a fellow-creature
in suffering_.' This rests upon the principle that to increase the
connotations of two terms by the same attribute or determinant does not
affect the relationship of their denotations, since it must equally
diminish (if at all) the denotations of both classes, by excluding the
same individuals, if any want the given attribute. But this principle is
true only when the added attribute is not merely the same verbally, but
has the same significance in qualifying both terms. We cannot argue _A
mouse is an animal_; therefore, _A large mouse is a large animal_; for
'large' is an attribute relative to the normal magnitude of the thing
described.

Sec. 4. Conversion is Immediate Inference by transposing the terms of a
given proposition without altering its quality. If the quantity is also
unaltered, the inference is called 'Simple C