names as predicates

[Guy Steele <cbmvax!uunet!Think.COM!gls>]

   From: cbmvax!snark.thyrsus.com!cowan@uunet.UU.NET (John Cowan)
   Date: Thu, 13 Jun 91 11:04:48 EDT

   > (My skepticism about the dichotomy of names and predicates
   > is related to my distrust of equality as a primitive notion
   > in predicate logic.  I suspect that the abstract notion of
   > equality misleads us concerning the nature of perception;
   > in this view, equality is properly applied--if at all--only
   > to abstractions and not to physical objects.)

   I don't understand this.  (BTW, by "equality" I assume you mean "identity";
   what is expressed by the Lojban word "du" or the Old Loglan equivalent "bi".)
   Why shouldn't identity be applied to physical objects?  It is simply that
   relationship which holds only between a thing and itself: the smallest
   reflexive relation, in Kripke's definition.

On Tuesdays and Thursdays I am willing to defend the position that
the notion of "thing" is not well-defined as applied to physical
objects.  It may be ontologically unjustified to build the assumption
that it is well-specified into the deep structure of Lojban.
Kripke's definition begs the question, for the very definition
of relation R being "reflexive" is that for all x and y,
x=y implies xRy.  (I won't accept a definition that reads,
"for all x, xRx" because that merely embeds the implicit
use of equality in the notation.)

   I would also like to take this opportunity to retract some of what I wrote to
   Steve Rice a while ago.  He stated that in Institute Loglan predicates and
   identities were distinct, and that "bi" did not express a predicate.  I
   half agreed that "du" did not either, being influenced by a notion that
   "du" expressed identities by definition.  However, the use of "du" as
   mathematical equality ("bi" is also so used) shoots that one down:
   2 + 2 and 1 + 3 are equal not by definition but because they are the same
   object, the number 4.  The statement:

	   li re su'i re du li pa su'i ci
	   the-number 2 + 2 = the-number 1 + 3

   represents a truth, as does its exact Institute Loglan equivalent
   "lio to poi to bi lio ne poi te".  Its truth is exactly on a par with
   the truth of any other true predication.

Right.  So if I can say  mi du la glis.  then why can't I say  mi la glis. ?