We like to pretend that summit conferences are less about personalities than they are about institutional issues -- a coming together of heads of government to take up the cosmic business of nations in a suitably sterile environment, ideally one that has room for the droves of clerks, cops and attendants each side brings. A vast, boring literature of summit theory has been developed by our political scientists and out-of-work diplomats over the years around this pretense. It addresses such abstract questions as how much preparation at what level must precede the ultimate meeting of the ultimate leaders. Never far from its surface is the condescending assumption that when these old fools get together they will almost certainly present a terrible danger not only to world peace but also to departmental priorities, so somebody has to keep them under control.

I will concede that summit conferences like the one coming up are about a lot of things that are governmental and institutional in nature: they can serve as deadlines for getting a little somewhere on arms agreements or as convenient occasions to sign off on already arranged small deals; they present opportunities to impress third parties around the world as to the relative merits of the participants -- their bearing, power and quality of mind. But essentially these conferences are about individuals meeting and dealing with each other in the flesh. Much of the rest of the business could be (and usually is) conducted without them, and much of the impetus for the meetings comes from the overwhelming curiosity that leaders -- especially those who are adversaries -- have about each other.

This is only logical, when you think about it. Leaders who live in a kind of constant hostile, long-distance intimacy yearn to see each other firsthand. Often as not, such meetings produce a weird rush of camaraderie and professions of respect for the godawful things one has almost succeeded in doing to the other in the past. Witness Richard Nixon and Chou En-lai, Golda Meir and Anwar Sadat. It is an ancient tradition. No one, in fact, was more interested in and hospitable to his royal adversaries than the great Muslim warrior Saladin, who held the crusaders at bay, although he did interrupt the amenities in his tent one day to whack off the head of one of the crusader king's companions whose attitude he found objectionable.

We can assume that nothing similar will happen in Geneva, if only because Reagan is prudently leaving so many of the prospective whackees, whose locus is the Defense Department, out of the talks. But what about the bonhomi? What about the personal encounter itself? Is it a good thing? Should it make us sleep better at night, or worse? I come down on the cheerful side, although I get there only by way of a hike up a hill of anxieties and after observing a number of things that can go wrong.

First there is the risk you take the minute you engage the prestige and the presence of the leader in the proceedings. He cannot be humiliated, misused or lied to without greatly raising the stakes in any international or bilateral conflict. I don't mean to come out for mendacity, at least not exactly. But it is true that lying to a secretary of state, while a violation of the Ten Commandments, is far less reckless and consequential than lying to a president. Jimmy Carter was said to have been lied to by the Soviets directly on the hot line, and John Kennedy by Andrei Gromyko, face to face, before the Cuban missile crisis. Lying directly to a head of government plays havoc with his belief that there is some level of verbal exchange in which he may have confidence, especially in time of emergency. It will undermine his willingness to take seriously anything that government says again.

A second risk proceeds from naivet,e and/or arrogance (the two often go together and not just in presidents). FDR thought he could charm, outwit and patronize Joseph Stalin. In both Ike and Kennedy there was some hint of feeling that Khrushchev could be, if not charmed, at least cajoled and favorably impressed into accepting our general outlook on the world. A third risk comes from failure. Khrushchev turned out to be and behave like a brute at his Vienna conference with Kennedy. He went home with a sense that the American president was a pushover. Kennedy went home knowing he had to take action to overcome that impression. Plenty of trouble followed.

Still, my bias is in favor of the direct encounters. I think that anything that creates and deepens a sense of the reality of the other players in these life-and- death games is good. They spend too much time as it is inhabiting a world of memos and briefings and brainstorming sessions. They only imagine each other. I don't trust their imaginations to be a good guide to either conciliation or combat.

In Washington journalism as well as in more extreme Washington politics, there is a school which holds that personal encounters are dangerous with anyone whose views and deeds you disapprove of or even whose behavior you are expected to be dispassionate about: knowing that the fellow has a nice child or a sick wife or a great store of jokes, it is feared, may undermine your capacity to do your job. But I think knowing more and understanding more about individuals, both in politics and journalism, helps you to analyze and deal with their ideas more realistically. Only the craven or the silly let the personal impressions overwhelm their professional judgment, reasoning that the fellow is such a good cook or father or raconteur that his position on MX must also be sound or that, despite a public record to the contrary, he really is "nice."

Surely Reagan isn't one of these. One of his greatest political gifts has been his ability to separate personal animus from ideological combat, to maintain personal civility and cordiality with those with whom he is contending mightily. I am not afraid that he will fall for Gorbachev or even that he will conclude that he knows all about him on the basis of a couple of days' visit. Both men will come away with a very strong impression that the other exists; their fantasies will be somewhat whittled down to size; they will henceforth be talking about reality in a way they haven't before. That can only be good.