Is the Cold War over? Not if Mikhail Gorbachev and his colleagues are having second thoughts about withdrawing Soviet troops from Europe.

Is the world becoming safer? Not if the United States accepts constraints on advanced weapons while dangerous Soviet intercontinental ballistic weapons remain unrestricted. Has democracy triumphed? Not yet. Not in the Soviet Union or China or almost anywhere in Asia outside of Japan. Not in the Middle East or Africa. While democracy spreads in Latin America, fundamentalism spreads in Moslem nations.

Reason has not yet replaced force in Kashmir or Lebanon, Gaza, Iraq or Lithuania. George Bush cannot write enough notes to comfort all the families of all the victims of violence -- in Nepal, Malaysia, Afghanistan, Jordan, Beirut and Nazareth. James Baker cannot cut enough deals to eliminate all the proliferating weapons of mass destruction.

It is not true that the case for democracy has vanquished all opposing philosophies, only that it has vanquished European Marxism. We have not arrived at the Heavenly City of 18th-Century philosophers or the Crystal Palace of 19th-Century prophets.

The fact is that no one knows what will happen next. The great movements of the 20th Century have come as a surprise. Communism, fascism, Nazism, Islamic fundamentalism -- each was an unexpected development. Each seemed unlikely even as it fastened a fanatical grip on an unwary society. Lenin and his Bolsheviks were as implausible a band of conspirators as ever moved into a volatile political situation. They were as implausible as Hitler and the freakish freebooters who met with him in Bavaria and Berlin, as implausible as the Ayatollah Khomeini and his frenzied followers, as implausible as the Chinese Red Guard or Pol Pot's baby-faced killers.

Ours is a century of violent revolutions, each more unexpected than the last. It is a century of utopian dreams and megalomaniacal revolutionaries who, as rulers, move their subjects about like so many pawns on a gigantic chessboard -- into cities, out of cities; from reeducation onto farms, from farms into reeducation.

Always the world is surprised. We are surprised that ''trends'' should change so rapidly, surprised that a man with a band of followers can have such an impact, surprised that grand schemes to collectivize, villagify and nationalize can produce so much murder and mayhem.

We are surprised by war and surprised by peace; surprised by economic growth (as in the Asian miracle), and surprised by economic failure (as under socialism). We were surprised by Stalin's ruthless conquest and by Gorbachev's abandonment of those conquests.

In truth we have not discerned the ''laws'' of historical development, probably because there are none. Individual leaders have a greater impact on history than we prefer to think, because individuals are so unpredictable. It is disconcerting, for example, to think that the theoretical speculation of a small band of exiles may shape the future of the world.

Much of what has happened since World War II has come as a surprise. And much that lies ahead will also surprise us. We did not foresee the resurgence of German and Japanese economic power, nor do we know the consequences for them or us of Japan's highly leveraged security market and wide-ranging acquisitions. No one anticipated the rapid liquidation of the Soviet Union's European empire. Nor did we foresee the Soviet government's sudden halt of its withdrawal from Eastern Europe. We do not know how long Mikhail Gorbachev will retain power or what his policies will be while he remains.

We are more involved with one another than ever, but that does not mean that we like each other better. Some Japanese dream of saying ''no,'' to America. Some French will not say ''yes'' to NATO or to a special role for the United States in Europe. The size and shape of the European community are less certain than Brussels pretends. Difficulties in breaking East Germany out of the Warsaw Pact expand that unknown. Uncertainty hangs as heavy as London fog over the future, obscuring it.

It is a good time now, in advance of the American-Soviet summit, for the U.S. government to step back and think again about a sweeping arms deal that does not affect the presence of Soviet troops and tanks in Europe or the continued production of ICBMs with a well-understood first-strike capability.

It is time for the Bush administration to reiterate Ronald Reagan's message at Reykjavik: A deal? Yes, but not at the price of enhanced American vulnerability in a still very uncertain world.