The important things in world affairs right now are not making newspaper headlines or film clips on TV news. They are the new ideas about weapons and East-West affairs which are being churned around in the scores of informal meetings and study groups which work behind the scenes of government in Washington and in all other important capitals.
We are now in the ''pre-decision'' phase of policymaking in Washington in which old ideas are being reexamined and possible new policies and programs are being studied, examined, tested, and refined.
In this churning process there are right now two important new words. One is ''interim.'' The other is ''Midgetman.''
''Interim'' means a policy position on European theater nuclear weapons to be put forward in the negotiations with the Soviets if the moment comes when it is apparent that both sides would prefer an arms-control agreement to an unrestrained arms race.
''Midgetman'' is a code word for a new version of the MX missile. The official MX weighs 96 tons and could be launched only from an expensive, fixed-base silo on land. The ''Midgetman'' weighs 11 tons and could be launched from moving vehicles on land, at sea, or in the air.
''Midgetman'' would have the same range (8,000 miles) and approximately the same accuracy rating (within 220 yards from target). It would have only a single warhead, against 10 for MX.
At the present moment the US position on theater nuclear weapons for Europe is the so-called ''zero'' option. The Soviets would remove all their new SS-20s and similar older missiles from the European theater. In return the US would refrain from putting its new Pershing II and cruise missiles into Europe.
The ''zero'' option is an opening position. Until Vice-President George Bush got back from his recent swing around NATO the White House was, in effect, saying it was also the final position. There was no public admission that any compromise was possible.
This hard-line position was outflanked in the propaganda game by an alleged Soviet willingness to consider withdrawing some SS-20s from Europe to bring Soviet nuclear weaponry down to a level nearer that of existing British and French nuclear weapons.
The maneuver gave Moscow the propaganda advantage of appearing to be flexible while Washington was still standing on an inflexible ''zero-zero'' position.
So now we have Washington talking of an ''interim'' position, meaning a partial scaling down in plans for deploying the new American weapons in Europe in exchange for a partial scaling down of the number of Soviet SS-20s already deployed.
Many a variation is possible if serious negotiations get going. Some experts think that not until some of the new US weapons are actually set up in Europe will the Soviets recognize that they cannot head off this deployment by propaganda alone. They are presumably hoping that anti-nuclear groups will prevent the deployment.
So perhaps the essential first step toward serious arms-control talks is convincing evidence that the United States and its allies will go ahead with the deployment. In the meantime Washington is thinking through the nature of an eventual compromise to be put forward if and when the time is ripe. The fact that it is doing this thinking now should repair the propaganda balance and persuade NATO public opinion that Washington does prefer arms control to an all-out arms race.
The essential fact behind this is that opinion within the Reagan administration is divided between those who prefer the arms race (on the theory that the US can stand the pace better than the Soviets) and those who would prefer controls. The ''controllers'' appear to be winning out over the ''racers, '' which is the really important news.
Meanwhile, the new thinking about weapons themselves adds a complication. In the negotiations over intercontinental weapons (as distinct from European theater weapons), most thinking until now has been on the assumption that the big 96-ton MX would be the next step in American strategic weaponry. If the big MX is to be abandoned and replaced by the 11-ton ''Midgetman,'' a lot of staff work will have to be done over again.
But even before that comes, the big tussle in Washington is among the armed services. The big MX would be an Air Force weapon. Since it would have to have a fixed land base, it is of no value to the Navy or Army.
The Air Force once controlled most military aviation. But the Navy never did give up its own air arm for tactical support. And the Korean and Vietnam wars saw the revival of an Army air arm for all close support work. That left the Air Force with two prime weapons systems - manned long-range bombers and land-based intercontinental missiles.
The issue coming up fast out of all the rethinking is whether an independent Air Force is any longer necessary or desirable. The manned bomber is considered by many experts to be nearing obsolescence, if not already there. And there are even more experts in the military study area who think the fixed land-based missile has been outdated by recent gains in missile accuracy. A movable missile on a truck, in an airplane, or on a ship is a difficult target to find and hit.
Originally all nuclear missiles were fitted with single warheads. The US introduction of the MIRV (multiple, independently targeted warheads) added a new dimension to the arms-control process. If everyone went back to the single-warhead weapon, it would be easier to work out a formula for controls.
The importance in all this is that the Reagan administration is doing a lot of fresh thinking about weapons, about negotiating with the Soviets, and also about the nature of the Soviet Union. There are some inside the administration who begin to talk as though they thought ''coexistence'' might be better than an arms race and economic cold war.
However, ''coexistence'' is not one of those code words in current use. It went out along with ''detente,'' which is still regarded in Reagan circles as bad. Someone will have to come up with a new word to express ''coexistence,'' because that is precisely what a few brave souls are beginning to think about in the back rooms where policy gets started.