Elements of the philosophy of the human mind. By Dugald Stewart. Rev. and abridged, with critical and explanatory notes, for the use of colleges and schools. By Francis Bowen ...

414 REASONING AND DEDUCTIVE EVIDENCE.
ored to show that we think, as well as speak, by means
of words, and that, without the use of language, our reasoning
faculty, if it could have been at all exercised, must necessarily
have been limited to particular conclusions alone. The effects,
therefore, of ambiguous and indefinite terms are not confined to
our communications with others, but extend to our private and
solitary speculations. Dr. Campbell, in his Philosophy of Rhetoric, has made some judicious and important observations on
this subject; and, at a much earlier period, it drew the attention
of Des Cartes; who, in the course of a very valuable discussion with respect to the sources of our errors, has laid particular
stress on those to which we are exposed from the employment
of language as an instrument of thought. " And, lastly, in consequence of the habitual use of speech, all our ideas become
associated with the words in which we express them; nor do we
ever commit these ideas to memory, without their accustomed
signs. Hence it is, that there is hardly any one subject, of
which we have so distinct a notion as to be able to think of it
abstracted from all use of language; and, indeed, as we remember words more easily than things, our thoughts are much more
conversant with the former than with the latter. Hence, too, it
is, that we often yield our assent to propositions, the meaning
of' which we do not understand; imagining that we have either
examined formerly the import of all the terms involved in them,
or that we have adopted these terms on the authority of others
upon whose judgment we can rely."
To these important considerations, it may be worth while to
add, that whatever improvements may yet be made in language
by philosophers, they can never relieve the student fiom the
indispensable task of analyzing with accuracy the complex ideas
he annexes to the terms employed in his reasonings. The use
of general terms, as Locke has remarked, is learned, in many
cases, before it is possible for us to comprehend their meaning;
and the greater part of mankind continue to use them through
life, without ever being at the trouble to examine accurately
the notions they convey. This is a study which every individual