"THE HOUSE yesterday narrowly voted to begin building MX missiles at a cost of $2.6 billion next year, despite the fact that all sides admit that no one knows where to put them." We quote the lead sentence from the lead story in yesterday's Post not, as you might imagine, to underscore the absurdity and wastefulness of what the House did or to register a complaint that its members failed to follow our advice--which was to have some idea of what it was going to do with these missiles before its started buying them. All that--the absurdity and wastefulness--is so self-evidently true, and the history of mismanagement and monsterism in this country's defense procurement practices so compelling, that we figured there must be more here than met the eye.

We will get around to what it is--to the good news--in a minute, but a little context is required first. As you no doubt remember, the big hang-up concerning the MX missile has been finding a place to put it where it will be invulnerable to Soviet attack, but not so well guarded from Soviet sight that they won't know how many we have. This latter knowledge is meant to reassure them that we have not built a mammoth first strike force of MXs, but are sticking to an announced number. Various so- called "deceptive basing" plans meant to satisfy these twin objectives were drawn up and one was chosen in the Carter years. But the idea of all those missiles being trucked around a vast race track at a couple of hundred sites in the West, occasionally to be revealed for photographing and counting by the Russians, was thought by many to be too elaborate and by persons living near the prospective sites to be out of the question.

Mr. Reagan, less concerned than his predecessor was with letting the Russians see for themselves, junked the Carter plan. But he has since been having a devil of a time coming up with his own. This was what led many in the House (and in the Senate, where production funds have been withheld) to insist that the money and commitment to buy follow, not precede, the decision on where, if anywhere, these missiles are to live and/or travel. There has been talk of a "cluster" or "dense pack" deployment --the current favorite--and now there is talk of a final decision to be made and revealed by the president by Christmastime at the latest. It was this pledge of a December decision on basing, apparently, that helped swing the last few votes for the missile in the House.

Do you realize what has happened? Do you begin to see the beauty of it? The House in cooperation with a baffled White House and a stumped Department of Defense and certainly to the chagrin of a perplexed and suspicious KGB has come up with the ultimate, ingenious deceptive basing system. No one, not even the people who are building the missiles, knows how or where they are going to be based. The December deadline for decision will no doubt be slipped (the deadlines for decision on this matter invariably are). We will get the MX missiles. There will be no basing system. The compromise voted in the House eliminated money for a basing system, in acknowledgment of the fact that there was none; so what you have is the money for the weapons.

Surely this is the best possible outcome so far as deceptive-basing is concerned. The MXs will merely be hustled around the country for the next couple of decades while the debate on where they should live proceeds. Of course, our scenario requires that the Senate withdraw its objections; but we do not doubt for a minute that it will have the good sense and patriotism to do so. In anticipation, we congratulate the House. All this for an eventual total cost of only $25 billion.