A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
While speaking of resemblance, it is necessary to take notice of an
ambiguity of language, against which scarcely any one is sufficiently on
his guard. Resemblance, when it exists in the highest degree of all,
amounting to undistinguishableness, is often called identity, and the
two similar things are said to be the same. I say often, not always; for
we do not say that two visible objects, two persons for instance, are
the same, because they are so much alike that one might be mistaken for
the other: but we constantly use this mode of expression when speaking
of feelings; as when I say that the sight of any object gives me the
_same_ sensation or emotion to-day that it did yesterday, or the _same_
which it gives to some other person. This is evidently an incorrect
application of the word _same_; for the feeling which I had yesterday is
gone, never to return; what I have to-day is another feeling, exactly
like the former perhaps, but distinct from it; and it is evident that
two different persons cannot be experiencing the same feeling, in the
sense in which we say that they are both sitting at the same table. By a
similar ambiguity we say, that two persons are ill of the _same_
disease; that two persons hold the _same_ office; not in the sense in
which we say that they are engaged in the same adventure, or sailing in
the same ship, but in the sense that they fill offices exactly similar,
though, perhaps, in distant places. Great confusion of ideas is often
produced, and many fallacies engendered, in otherwise enlightened
understandings, by not being sufficiently alive to the fact (in itself
not always to be avoided), that they use the same name to express ideas
so different as those of identity and undistinguishable resemblance.
Among modern writers, Archbishop Whately stands almost alone in having
drawn attention to this distinction, and to the ambiguity connected with
it.
Several relations, generally called by other names, are really cases of
resemblance. As, for example, equality; which is but another word for
the exact resemblance commonly called identity, considered as subsisting
between things in respect of their _quantity_. And this example forms a
suitable transition to the third and last of the three heads under
which, as already remarked, Attributes are commonly arranged.
V. QUANTITY.