Re: Existence, Self-identity and Uniqueness.

Chris Menzel wrote:
In his original post, Owen appears simply to be introducing definite
descriptions (i.e., expressions of the form "(the x:Fx)") á la Russell
as "incomplete symbols" -- they are not genuine singular terms in the
language, but only occur as parts of convenient definitions for more
complex expressions. Hence, they not available for substitution in
inference patterns like universal instantiation. So construed, his
introduction of definite descriptions does not take him beyond the
bounds of FOL=.

But it seems to me that he used the form "the x:Fx"
as well in substitutions. Because he went for
example from:

D1. E!x =df x=x

to:

E!(the x:Fx) <-> (the x:Fx)=(the x:Fx)

Thus he instantiated a form "x in E!x"
for x in E!x. Actually substitution is
quite part of his proof.

Bye

.

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