Keelefilosoofia raamat
At the time,
we replied simply that, even if propositions do not help in the explanation
of human behavior, behavior is not the primary thing that needs explain-
ing; rather, the meaning facts are. But the objection has been pushed further
against both versions of the Truth-Condition Theory.
Objection 7
There is still a problem of substitutivity. For there seem to be contexts in
which synonymous (not just coextensive) terms cannot be intersubstituted
without possible change of truth-value. "Ophthalmologist" and "eye doctor"
are synonymous (or so we may suppose for convenience). But, if Sheila does
not know that, "Sheila believes that every eye doctor doctors eyes" may be
true while "Sheila believes that every ophthalmologist doctors eyes" is false;
likewise "Irving went to an ophthalmologist because an ophthalmologist is
an eye doctor" is true while "Irving went to an ophthalmologist because an
eye doctor is an eye doctor" is false.
annaabi.ee 
