TO take no sides in history would be as false as to take no
sides in life,'' the historian Barbara W. Tuchman once wrote. If
that applies to the written word, it is just as true for the
presentation of history in museums. Museums can't be objective
because history isn't. To be meaningful, a museum needs a slant.
On the other hand, a museum dedicated to the history of a place
is supposed to be broadly representative. So there's the
contradiction: if a museum is doing its job, you might say, it's
ticking somebody off.  By that yardstick, the custodians of
three of the main museums devoted to New York history are doing
a terrific job. At receptions, in the newspaper, at meetings of
their boards, the future of New York's past is being discussed
in strident terms. The heightened political climate this fall is
adding effervescence. And the backdrop and catalyst is the event
of three years ago that refocused New York in the eyes of the
world.  For a long while, people have lamented a lack in New
York. Go to London,