Re: Enemy [Was: [lojban] Request for grammar clarifications

[John Cowan <jcowan@reutershealth.com>]

Robin Turner wrote:


> I don't see any harm, however, in using {du} to emphasise that the 
> expressions on either side have the same referent.


That is, indeed, its purpose.

Identity

The term is used loosely. We speak of identical twins. We say that
you and I drive identical station wagons. But for all the looseness
of common usage, the term in its strict sense is as tight as a term
can be. A thing is identical with itself and with nothing else,
not even its identical twin.

David Hume was puzzled. Identity seems like a relation, but it does
not relate things pairwise as a relation should; things are identical
only to themselves. How then does identity differ from a mere
property? Moreover, it applies to everything. How then does it differ
from the mere property of existence, the property enjoyed by everything?

It is hard to project oneself into the confusions of even so gifted
a mind as Hume's, after those confusions have given way to the progress
of science. A [binary] relation is now clearly conceived as consisting
of pairs of objects; the uncle relation comprises all the uncle-nephew
and uncle-niece pairs. The identity relation comprises all and only
the repetitious pairs, <x,x>; <x,x> is still not to be confused with x.

...And there are the makings of further confusion in the following
reflection: evidently to say of anything that it is identical with
itself is trivial, and to say that it is identical with anything else is
absurd. What then is the use of identity? Wittgenstein put this
question.

Genuine questions of identity can arise because we may refer to
something in two ways and leave someone wondering whether we referred
to the same thing. Thus I mention Simon, someone mentions Peter, and
we explain that Simon /is/ Peter; they are identical. It is neither
trivial to say so nor absurd to doubt it.

There is little need to give a man two names, nor much interest in
developing an identity-concept solely for that contingency. What is
more important is reference to something not by two names but by
two descriptions, or by a name and a description. We need to be
able to identify Ralph with the man who mows the lawn, and his
house with the one nearest the station. Identities such as these
permeate our daily discourse.

[section on continuity of identity snipped]

A vital use of identity lurks unobserved in much of our use of
'only' and 'else' and 'nothing but'. When I say that the hiding
place is known to Ralph and only him, nobody else, I mean to
say two things: that Ralph knows the hiding place and that
whoever knows the hiding place is identical with Ralph. To
say that there is no God but Allah is to affirm, of whatever
Gods there be, that Each, or He, is identical with Allah.

--W. V. Quine, _Quiddities_, s.v. "Identity"

--
There is / one art || John Cowan <jcowan@reutershealth.com>
no more / no less || http://www.reutershealth.com
to do / all things || http://www.ccil.org/~cowan
with art- / lessness \\ -- Piet Hein