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

the end of science. Here,
DEFINITION. I/p
"the business of definition
is part of the business of discovery"; "discovery and
definition go hand in hand." We begin by thinking
of an object in a loose general way as a whole made
up of parts which are familiar. Such an idea may
be little more than a mental picture : but as long as
it is precise enough to avoid confusion with other things,
we are practically content. But reason suggests a
step in advance, to ascertain the characteristics which
the object has in common with other species of its
genus, and also to distinguish it from the other species.
Then we are led to inquire into the general law which
regulates the connection of its parts, the "what" of
the thing ; and the form which this knowledge tends
to take is that of the causal conditions i.e.,
origin
the real
of the object, the
" "
how of the thing. We may
therefore say that some definitions are provisional and
progressive, while others are final, in the sense that to
reach them is the ideal of science.
It has even been held (cp. Aristotle, An. Post., ii. 10) that
ideal definition will show the of the "why" thing, the very
reason of its existence ; but, short of this, many of the results
which we should call "laws of Nature" would have been
called "definitions" by the Greeks. Aristotle would have
called Newton s Law of Gravitation, or Darwin s theory of
Natural Selection, scientific definitions of "Gravitation"
As Geometry was in a far more advanced
"
and of Species."
state, among the Greeks, than any natural science, they
"
"
took this as their model of scientific knowledge (eTrio-T^/w??)
and, since in Geometry it is easy to sum up results in a brief
formula, it was natural to speak of these results as "defini
tions" rather than "laws." Thus, from this point of view,
the whole of the Third Book of Euclid, which deals with
properties of circles, is an expanded definition of the circle.
Before leaving this
subject, there are some particular
types of definition which we must notice. In mathe-