I have this fantasy that one day soon -- suddenly, overnight -- all the projects and commissions and presidential undertakings to eliminate waste from the Defense Department work. They bear fruit. Savings in the tens of billions, without any diminution of military strength, are foreseen. Then a funny thing happens. An emergency meeting is called for the purpose of either burying the proposals or thinking up new ways to spend at least as much as will be saved if they are put into effect. There is a need to do this, the participants are told, because the size of our expenditures on defense has become not just a measure of our strength, but also an element in our discourse with the Soviet Union -- a sign, a signal, a weapon of sorts itself -- and we are not free to make dramatic savings.

All right. I will not defend the verisimulitude of any feature of this weird meditation. None of it could happen. But that only puts it in the category defense planners call "worst case." What it is the worst case of is military monevitis, a form of the more widespread general ailment that regards gross amounts of money spent on a particular project as a suitable measure of public purpose, national values and even the presumed competence of those getting the money. I think Ronald Reagan, who simultaneously committed himself to (a) draconian measures to eliminate unnecessary government spending and (b) a steady rise in the defense budget as a way of letting the world know what we are about, has embroiled himself in a contradiction that could prove costly.

I'm not arguing here against the need for great improvements in the American defense enterprise, only against the automatic assumption that money spent on that enterprise is a reliable guide to how improved it will be. It is self-evident that many required improvements (especially in the manpower field) will cost plenty. But "more" is not necessarily stronger. And "less" is not necessarily weaker -- nor (to take another argument) is it necessarily more peace-loving and less provocative to cut your defense expenditures by some prescribed percentage or amount. This last idea was in vogue among many Democrats in the late '60s and throughout the '70s. One heard about 5 percent cuts and $50 billion limits and things like that as a way of "reordering national priorities."

The implication here is the same for domestic -- specifically social-program -- expenditures as for those earmarked for the military. It is that these figures, crude and unrevealing of details as they might be, tell an essential story about the intentions of the political society that has authorized the totals to be spent. For example, you will hear lots of people presuming to judge the degree of our compassion as a nation, our fundamental decency even, by the magnitude of the budget for domestic social programs and other operations ostensibly intended to make life more attractive, or merely more endurable, for more people. Here, too, however, crude measures lead to fairly crude and not very helpful conclusions.

This is especially true when the social-program versus defense expenditure comparison is undertaken. In the Nixon years a great deal of whoop-de-doo was made by administration spokesmen concerning the fact that the social-program share of the budget had overtaken that for defense right there under the noses of the people who were complaining that this was militaristic crowd -- Imagine! And no one was giving them credit for this great reordering of priorities and so forth. It was, however, not a burst of Nixonian tenderness, but a rise in the so-called "uncontrollables" authorized by Congress (e.g., Social Security) that accounted for the new proportions.

With Caspar Weinberger, a former budget director at Defense, and David Stockman, a compulsive student of the unintended effects of federal budget decisions at OMB, there is no way this administration can be unaware of the crippling flaw in the gross expenditures money-test. For years defense critics used to ponder the question: how much is enough? That question is no less important now for having been understood to be relevant only after you have answered a prior question, namely, where does the money you are actually spending go?

Before Stockman was even in Congress he was conducting studies along this line, demonstrating, among other things, that much of the Great Society outlay on what were agreed to be beneficent public goals was ending up in the pockets of consultants, bureaucrats and assorted social-program enterpreneurs who could by no stretch of the imagination be called poor or even strapped. In defense too -- perhaps even more so -- the where-does-it-actually-go test is the critical one. James Fallows, in his important new book, "National Defense," has spelled this out, citing extremely costly projects that are not just wasteful but actually harmful to the quality of our national security.

A lot of the money the Reagan administration has proposed spending since it came to office consists of funds that won't in fact be spent for some time to come. And much of it is for essential workaday improvements that hardly anyone would quarrel with. But to the extent that the administration gets committed to big and exotic systems with big and exotic price tags meant to impress and intimidate people who don't much like us around the world, the sheer size of the proposed expenditure can as readily mean trouble, waste and weakness as the strength and commitment it is meant to convey.

The whole military procurement and planning process, with its endless lead times and its pressures generated by congressional committees and contractors and politicians, is a model of how not to get a weapons system, or any other, into being. It needs work, to understate the case. The condition of the economy (hardly unrelated to our national security) imposes its own limits on what a prudent government should spend. I would think Reagan needs all the maneuvering room he can get in such a situation. That is why it strikes me as so unfortunate that the money-test has been transformed into some kind of diplomatic message to the Russians. I think it could be our most expensive and least successful weapon.