A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
What would otherwise be a mere description, may be raised to the rank of
a real definition by the peculiar purpose which the speaker or writer
has in view. As was seen in the preceding chapter, it may, for the ends
of a particular art or science, or for the more convenient statement of
an author's particular doctrines, be advisable to give to some general
name, without altering its denotation, a special connotation, different
from its ordinary one. When this is done, a definition of the name by
means of the attributes which make up the special connotation, though in
general a mere accidental definition or description, becomes on the
particular occasion and for the particular purpose a complete and
genuine definition. This actually occurs with respect to one of the
preceding examples, "Man is a mammiferous animal having two hands,"
which is the scientific definition of man, considered as one of the
species in Cuvier's distribution of the animal kingdom.
In cases of this sort, though the definition is still a declaration of
the meaning which in the particular instance the name is appointed to
convey, it cannot be said that to state the meaning of the word is the
purpose of the definition. The purpose is not to expound a name, but a
classification. The special meaning which Cuvier assigned to the word
Man, (quite foreign to its ordinary meaning, though involving no change
in the denotation of the word,) was incidental to a plan of arranging
animals into classes on a certain principle, that is, according to a
certain set of distinctions. And since the definition of Man according
to the ordinary connotation of the word, though it would have answered
every other purpose of a definition, would not have pointed out the
place which the species ought to occupy in that particular
classification; he gave the word a special connotation, that he might be
able to define it by the kind of attributes on which, for reasons of
scientific convenience, he had resolved to found his division of
animated nature.