s
master flatters himself that he has early taught him to reason
philosophically. But what ideas does the youth annex to the words
pleasure and virtue? Or does he annex any? If he annex no idea to the
words, he is merely talking about sounds.

All reasoning ultimately refers to matters of fact: to judge whether
any piece of reasoning is within the comprehension of a child, we must
consider whether the facts to which it refers are within his
experience. The more we increase his knowledge of facts, the more we
should exercise him in reasoning upon them; but we should teach him to
examine carefully before he admits any thing to be a fact, or any
assertion to be true. Experiment, as to substances, is the test of
truth; and attention to his own feelings, as to matters of feeling.
Comparison of the evidence of others with the general laws of nature,
which he has learned from his own observation, is another mode of
obtaining an accurate knowledge of facts. M. Condillac, in his Art of
Reasoning, maintains, that the evidence of reason depends solely upon
our perception of the _identity_, or, to use a less formidable word,
_sameness_, of one proposition with another. "A demonstration," he
says, "is only a chain of propositions, in which the same ideas,
passing from one to the other, differ only because they are
differently expressed; the evidence of any reasoning consists solely
in its identity."

M. Condillac[91] exemplifies this doctrine by translating this
proposition, "The measure of every triangle is the product of its
height by half its base," into self-evident, or, as he calls them,
identical propositions. The whole ultimately referring to the ideas
which we have obtained by our senses of a triangle; of its base, of
measure, height, and number. If a child had not previously acquired
any one of these ideas, it would be in vain to explain one term by
another, or to translate one phrase or proposition into another; they
might be identical, but they would not be self-evident propositions to
the pupil; and no conclusion, except what relates merely to words,
could be formed from such reasoning. The moral which we should draw
from Condillac's observations for Practical Education must be, that
clear ideas should first be acquired by the exercise of the senses,
and that afterwards, when we reason about things in words, we should
use few and accurate terms, that we may have as little trouble as
possible in changing or translating