THE PRESIDENT'S prospective cuts in government programs are very much in the news. And the poor, as a group, are likely to bear the major part of the burden of sustaining them. Before the budget debate mires down in the technicalities of who is eligible and for what assistance -- or blows up into a volley of charges about welfare cheaters met by countercharges of cruelty to the poor -- it is fair to ask just who are the nation's poor in this day and age, and do they really need all this help?

Naturally, social scientists, who are generally not poor, disagree as to what being poor means and who fits the definition. People's needs and hardships vary in ways that government statistics can't capture, and it gets harder every year to get people to tell you what they have on hand, or at least on call, in the way of money and other resources. But by the federal government's official way of counting, there are now about 25 million poor people in the United States. They come in every age, race and background. Two-thirds of the poor are white, 41 percent are men, almost 50 percent are neither very old nor very young. But some people -- notably the old, the racial and ethnic minorities, women heading families and children -- have above-average likelihoods of being poor. With some combination of these characteristics, the likelihood can get very high -- 40 percent of elderly black women and over two-thirds of black and Hispanic children in female-headed families, for example are poor.

In recent years, poverty has also become increasingly urban. Over 60 percent of the poor now live in metropolitan area, almost 40 percent of them in inner cities. These are the places where poverty seems most bleak and the chances of escape most limited. While 42 percent of the poor still live in the South, poverty has declined rapidly in that region while growing elsewhere. And the poverty profile, especially among blacks, is increasingly dominated by the archetypal welfare family: the husbandless mother and her two or three children. Such families now account for one-third of all the nation's poor.

How well has the country done in combating poverty? By some measures, pretty well. The number of poor people has fallen from 22 percent of the population 20 years ago to less than 12 percent now. True, virtually all of that decline came in the booming 1960s. But holding the poverty percentage constant in the 1970s was no mean task. While declining birth rates at all income levels helped to curb the growth in welfare rolls, the number of people in "high-risk" categories -- the old, racial and ethnic minorities, women heading households, and immigrants (both legal and illegal) -- grew faster, and in some cases much faster, than the general population grew.

Substantial credit for what success there was -- in particular the 1.5 million reduction in the number of aged poor over the last 10 years -- must go to government programs. Without those benefits, over 40 million people would be in the official category of poor instead of the 25 million now counted. And if you add in direct assistance that comes in a form other than cash, like food stamps and housing subsidies that have grown rapidly in recent years, the poverty number falls to between 12 million and 17 million depending on what benefits are counted and how they are valued. If a reliable way could be found to adjust for extra-legal income and other discrepancies in the poverty count, poverty might be made to seem to have almost disappeared.

Is the war on poverty won then? Emphatically, no. In the first place, when we say "poor," we mean very poor. The official poverty line is set at less than 60 percent of what the government says a family needs to maintain even a "lower living standard." And, in some sense, poor is poorer than it used to be. A poverty income has, by definition, stayed constant in purchasing power while family income has doubled since 1950, even after adjusting for inflation.

More than ever, being poor also means being dependent on government programs. During the 1960s, many people (mostly men) did earn their way out of poverty, especially in rural areas and the South. But the number of "working poor" families (now mostly headed by women) has stayed almost constant over the 1970s while the number of poor and near-poor families who are totally dependent on government benefits has increased substantially.

Getting out of poverty hasn't meant much in recent years either. Most of the formerly poor have moved only a few hundred dollars above the poverty line, and many would fall back if their benefits were cut.

The poor are still very much with us. And it is sobering to think that many of the adults among them, who now have children of their own, were children themselves less than 20 years ago when the nation set out in earnest to conquer poverty. Have our efforts been in vain? Not at all. A smaller part of our population is in dire misery than ever before in our nation's history.

President Reagan said in his economic speech last week, "We can, with compassion, continue to meet our responsibility to those who through no fault of their own need our help." That's entirely right. As the budget-cutting begins, it will be necessary to keep constantly in mind exactly who these people are and how they will be affected. They are not only the millions now classified as poor; they are also the millions more who have been lifted out of desperate want by federal benefits and now depend on those benefits to keep them there, not as a matter of choice but of necessity.