THE debate over whether armed face-offs are the result of mistrust - or the other way around - has always been intellectually and politically interesting. But it's pretty much irrelevant since the two feed on each other, with the result that it is very hard to disarm. That's been the sad and frustrating history of the past 15 years as conventional arms reduction talks got nowhere. The important thing about the new set of talks opening today in Vienna is that - for the first time since NATO and the Warsaw Pact rushed to fill the post-World War II vacuum in Europe - the possibility of conflict, the probability of attack by either side, is so low that there is a real chance for disarmament. It's a chance that should not be missed.
There are some very good points in what's been offered by both sides so far, points of agreement that form a solid basis for progress: That disparities in the two alliances' arsenals and troop levels should be removed. That those arsenals and troop levels should be substantially reduced. And that there should be strict measures to insure that neither side cheats.
In essence, it's a backing down so that surprise attack designed to overwhelm the other side militarily and make it capitulate politically is far less possible. The important bottom line is increased stability, which should be the goal in any arms control negotiation, more important in fact than the weapons numbers themselves.
There are important differences between the two sides, of course, mainly involving battlefield nuclear weapons as well as naval and air forces which can be moved into combat positions more quickly than ground troops.
The United States seems to want to go a little slower than the Soviet Union in affecting deep cuts in conventional arms. Again, this illustrates how trust and disarmament have to track in parallel and about the same speed.
The negotiating will be vigorous and difficult, and it should be. But the atmosphere is good. For as British foreign secretary Sir Geoffrey Howe said this week, ``There is a real sense of hope that we can put the 40 years of cold war behind us.''