The tie between linguistic entities (e.g., words)
and their meanings (e.g., objects in the world) is
one that a reasoning agent had better know about
and be able to alter when occasion demands. This
has a number of important commonsense uses.
The formal point, though, is that a new treatment
is called for so that rational behavior via a logic
can measure up to the constraint that it be able
to change usage, employ new words, change mean-
ings of old words, and so on. Here w e do not offer
a new logic per se; rather w e borrow an existing
one (step logic) and apply it to the specific issue
of language change.
