Summits have led to major historic changes in this century - excessive German reparations after World War I that helped sow seeds of war II, tacit recognition of Moscow's Eastern European sphere, a new US-Chinese open door, US-Soviet detente, a slowing of the arms race.
One summit led to an increase in East-West tensions - over Berlin. One summit , in Glassboro, N.J., led to a rediscovery of the origin of the slang term ''booze.'' Another led Nikita Khrushchev almost, but not quite, to Disneyland.
Given this checkered history, would a Reagan-Chernenko summit be productive, risky, or neutral? Should it be meticulously negotiated and scripted, or should it have only a simple agenda? Should we rush to get it under way before the American election gives Mr. Reagan a new mandate, or a successor, on Jan. 20?
In recent months I've discussed summit realities with many specialists - including Soviet affairs authorities, arms control experts, and the man who carried a Reagan overture to Moscow last winter. These are some conclusions put forward by these Sherpas of the summit scene:
- Reagan and Chernenko are correct when they say an initial summit ought to be carefully prepared in advance. Mr. Reagan softened that stance at his June 14 press conference. But some key advisers say they still believe careful pre-negotiation is necessary. There are too many unknowns, too many bruised feelings, to make ''winging it'' advisable.
- Establishing personal rapport can take place in informal sessions around the fringes of the prepared, formal meetings.
- Later summits between the two leaders could be of the less-prepared, low-key, low-expectation, exploratory type.
- A custom of holding a get-acquainted summit within a few months of the selection of a new leader on either side could be built up over time. But a desire to create that precedent should not cause a rush to a summit now without careful planning.
- Mr. Reagan is sincere about wanting to go into the history books as a president who brought about a major reduction in the arms race. But there is also an element of election-year politics in his sharp turn toward wooing the Politburo leaders last winter.
- The Russian leaders have likewise been playing American election-year politics in recent months. But they have boxed themselves into a position where it appears they are aiding the man they didn't want to - Mr. Reagan - whatever they do.
By merely talking favorably about a well-prepared summit just before the Reagan press conference, Kremlin spokesman Leonid Zamyatin handed Reagan a campaign gift. First, it gave him a chance to make his very forthcoming press conference reply. (The White House now says limited economic talks are to resume and it is softening its opposition to talks on curbing development of antisatellite space weapons.) Second, it defuses the argument that he has been so tough the Soviets will boycott him indefinitely. Third, it makes any Moscow move back to tough talk on summits or arms control seem obdurate after Reagan's reasonableness.
Ironically, the Kremlin's move appears to undercut Walter Mondale's portrayal of Reagan as a war risk.
- Annual summits of the US president and Soviet general secretary ought to be approached cautiously. In theory they make sense in an increasingly close world society. But several pitfalls need to be avoided.
Any regular ''adversarial'' summits should be coordinated with leaders of the seven Western nations who meet in ''friendly'' summits each year. And, just as the friendly summits need to be reformed to end their circus atmosphere, a US-USSR event would need to be kept from excessively raising or dashing world hopes. Forethought should be given by both sides to the risk of a later break-off. What would Washington do about a future Afghan invasion or Polish crisis? Moscow about US troop moves in Central America?
One Soviet affairs specialist who served in the White House and is now an academic suggests that if a tradition of annual summits is built up, it should be a tradition in which some years heads of state meet, and some years their foreign ministers, defense ministers, or finance ministers meet. With that system, there could be continuity even in time of frosty relations. The head of state could express his disapproval by not going personally, but business could be carried on by the appropriate Cabinet officials. A relationship of this sort existed informally during some of the worst years of the Vietnam war. The Russians carried on so-called ''compartmentalized'' relations even while US bombs fell near Russian advisers in Hanoi and Russian ships carrying weapons to Haiphong.
Brent Scowcroft - the widely respected general who was President Ford's national-security adviser - sees annual summits as hard to start, but easier to sustain once started. General Scowcroft headed Mr. Reagan's strategic weapons commission, and carried a secret message from Reagan to Mr. Chernenko (rebuffed) in March.
''It's one thing to have regular meetings after you have established the precedent,'' he says. ''It's another thing to start them. I don't think you can start them without raising expectations. Had, for example, the meetings of the early '70s (Nixon and Brezhnev) become annualized affairs so that nobody expected too much from them, then . . . you could change the whole character of the meetings. That was one of the blessings of the early Western summits. At Rambouillet, (French President) Giscard wanted the heads of state and one adviser. Nobody else. Now, the last picture I saw, they were wall-to-wall. It changes the whole complexion.''
General Scowcroft, now vice-chairman of the international consulting firm, Kissinger Associates, is also cautious about a type of subsummit meeting often proposed: parleys of the US and Soviet joint chiefs of staff.
''I think it's all right,'' Scowcroft says. ''But I think such meetings are overrated as being fruitful. We've only had one. That was in 1979. . . . I don't see a great deal coming from (such a military parley). But it does little harm, and it could help.''
On the subject of regular, low-key, low-expectation summits for the American and Soviet heads of state, one former White House aide suggests the UN as a site. Every September and October, many heads of state come to New York to speak to the UN General Assembly. They, or their foreign ministers, engage in a round robin of informal talks in national missions or hotels in Manhattan.
It would be easy for Mr. Reagan and Mr. Chernenko to join this crowd and see each other with perhaps less hoopla than in each other's capital or in Geneva or Vienna. It would also be easier for this to become a yearly event of considerable flexibility. Some years the meeting could be at the top level. Other years it could be carried out, as has been the practice, between the two foreign ministers. Popular hope would not rise or be dashed as much by these variations as by the holding or canceling of summits elsewhere.
Earl W. Foell is editor in chief of The Christian Science Monitor.