Edition: U.S. / Global  Separate Social Security?  Published:
March 11, 1999  To the Editor:  Charles J. Zwick's and Peter A.
Lewis's attack on a plan to separate Social Security from the
Federal budget is unconvincing (Op-Ed, March 4).  Their argument
was that common people couldn't do simple arithmetic to
understand the full impact of Government spending in the economy
with separate budgets.  The writers also claim that the old wall
between Social Security and the rest of the budget was a
''relic'' and not an important barrier of fiscal responsibility,
which it was.  On the other hand, they were right when they said
that the overall budget would ''look worse'' if Social Security
was taken out of the equation.  It will, and it is up to
responsible legislators to provide sound fiscal leadership and
not rely on our retirement fund to balance the Government's
books.   New York, March 4, 1999