A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
confirms the indication of common sense, that the function of names is
but that of enabling us to _remember_ and to _communicate_ our thoughts.
That they also strengthen, even to an incalculable extent, the power of
thought itself, is most true: but they do this by no intrinsic and
peculiar virtue; they do it by the power inherent in an artificial
memory, an instrument of which few have adequately considered the
immense potency. As an artificial memory, language truly is, what it has
so often been called, an instrument of thought; but it is one thing to
be the instrument, and another to be the exclusive subject upon which
the instrument is exercised. We think, indeed, to a considerable extent,
by means of names, but what we think of, are the things called by those
names; and there cannot be a greater error than to imagine that thought
can be carried on with nothing in our mind but names, or that we can
make the names think for us.
§ 3. Those who considered the _dictum de omni_ as the foundation of the
syllogism, looked upon arguments in a manner corresponding to the
erroneous view which Hobbes took of propositions. Because there are some
propositions which are merely verbal, Hobbes, in order apparently that
his definition might be rigorously universal, defined a proposition as
if no propositions declared anything except the meaning of words. If
Hobbes was right; if no further account than this could be given of the
import of propositions; no theory could be given but the commonly
received one, of the combination of propositions in a syllogism. If the
minor premise asserted nothing more than that something belongs to a
class, and if the major premise asserted nothing of that class except
that it is included in another class, the conclusion would only be that
what was included in the lower class is included in the higher, and the
result, therefore, nothing except that the classification is consistent
with itself. But we have seen that it is no sufficient account of the
meaning of a proposition, to say that it refers something to, or
excludes something from, a class. Every proposition which conveys real
information asserts a matter of fact, dependent on the laws of nature,
and not on classification. It asserts that a given object does or does
not possess a given attribute; or it asserts that two attributes, or
sets of attributes, do or do not (constantly or occasionally) coexist.
Since such is the purport of all propositions which convey any real
knowledge, and since ratiocination is a mode of acquiring real
knowledge, any theory of ratiocination which does not recognise this
import of propositions, cannot, we may be sure, be the true one.