It is a measure of the cynicism in which Washington abounds that President Reagan's budget message has been greeted with widespread doubt. No one seems to think that the man means what he says.

>I am not referring now to the questions about the economic assumptions underlying the budget or the wisdom of his policies, both of which are surely open to debate. The undeserved cynicism is the belief that Reagan and budget director David A. Stockman must know their proposed spending cuts are unrealistic and are just setting up Congress to be the fall guy when deficits soar well beyond the already astronomical levels they are projecting.

I think Reagan means to do exactly what he says, and that if he succeeds this year, he will have recast the American government in a form that would have been unthinkable before 1980.

>In 25 years of budget-reading, I have been through more than my share of documents designed to camouflage the true character of the policy choices the president has made. This Reagan-Stockman budget, far from disguising the choices, slaps you in the face with them.

In the plainest language yet put forward, this budget says that the clear, concerted and forcefully applied strategy of this administration is to grind down the domestic side of the national government between the millstones of a rising defense budget and a declining tax base.

>It is what Reagan himself calls "a long-overdue reordering of priorities," and what many others will see as an abandonment of national responsibilities. In the slightly bureaucratic language of the budget, "the structural changes" Reagan is proposing "will result in radically asymmetrical patterns of budget growth in the years ahead." It means that defense, Social Security and medical programs will continue to grow and virtually everything else will shrink.

>And not by a little bit either. If Reagan has his way, those domestic programs--for agriculture, energy, transportation, education, environment, housing, manpower and the rest--will shrink in absolute terms every year for the next five years.

>No more of the 1981 rhetoric about "cutting the growth rate." He is talking about fewer dollars--and much less purchasing power--every year than the year before: one-third less in 1987 than this year, if the president has his way.

>The biggest whack will come this year, as Reagan tries to shrink these domestic programs before he hands them back to the states under his federalism initiative. He proposes to cut non-defense and non-entitlement net spending by 25 percent in one year-- and a recession year, at that, when most family, community and state budgets are already strained.

>The list of the programs that would be slashed extends all across the domestic side of government. The cries of pain make the 1981 budget fight seem a tame affair.

You can pick your own cause and file your own complaint. I find it shameful that in a $750 billion budget, Reagan would propose the total elimination of the legal services program that, in my experience, is the first and only guarantee many people have found for securing the law's protection against those who chisel and prey on the poor and helpless.

>The $150 million cost of that program is the price of 10 of the newest armored attack helicopters--or the amount a handful of corporations saved by buying other companies' tax credits.

>Cutting another $400 million from aid to schools teaching the educationally disadvantaged--on top of the $600 million cut last year--is robbing us of our future. This program was pronounced a rousing success last month by Reagan's own secretary of education as a way to bring children of deprived backgrounds into the mainstream of their schools. If you believe that public education is the building block of this democracy, that cut is unconscionable.>

>But the Reagan budget, in its candor, makes it very clear why he thinks it necessary. There is a lock between his determination to reduce tax rates and his insistence on pushing up defense spending at an unprecedented pace. As the budget shows, 97 cents of every dollar of added revenues the economy generates this year will--on Reagan's plan--go to the Defense Department. Next year, it will be 89 cents, and so on.

>The message to Congress could not be clearer: unless it is prepared to roll back Reagan's tax cuts or reduce his plans for the Pentagon, there is no way to finance the domestic budget of the national government. The only argument remaining is the pace at which it is dismantled.

>Reagan has put the challenge in the clearest, least cynical terms for all to see. Now it is up to Congress and the ountry to say if that is what we want.