The debate rages over Charles Murray's book "Losing Ground." Has he conclusively proved that Great Society programs hurt rather than helped the poor and therefore should be repealed? Or is he a hit-and-run mercenary in the pay of right-wingers who twists the numbers in order to kill off programs that do help the poor?

The arguments are made with a thunder and fury suggesting that the future of Aid for Families with Dependent Children and food stamps and Medicare and Medicaid depend on the outcome. But it doesn't: Murray is quick to admit that his proposal to abolish such programs (but not unemployment insurance) is visionary and exceedingly unlikely to be adopted.

This is not a book to change society but a book to show society how it has changed. Like the education reports that came out in the spring of 1983, "Losing Ground" articulates feelings that millions of Americans have already acted on.

Murray and his critics tend to miss this point because their debate concentrates on the book's economic argument. Rep. Jack Kemp says that if you subsidize something, you get more of it. Murray says that if you pay people who are poor or dependent you get more of them. But he is careful not to assert what his critics seem bent on disproving: that there is a one-to-one relationship between increases in benefits and welfare dependency or the various other kinds of negative behavior he describes. He concedes that AFDC payments declined in real dollars since 1970 and that the AFDC rolls nonetheless have held steady since then.

Similarly, Murray's critics are careful not to argue that transfer programs are never a disincentive to work or an incentive to antisocial behavior. Though they point to gains in health among the poor (Murray tries to put these aside by saying he's not talking about health programs), the critics are all too aware of the dreadful statistics that Murray points out: for an agonizingly large number of poor and especially of black poor, life has gotten worse rather than better even as transfer programs have gotten more generous.

Neither side dares to say that purely economic arguments -- incentives and disincentives -- can tell us whether transfer programs are worthwhile. At best they can help us answer the practical questions politicians grapple with every day: should we cut this program a little or increase that one a bit?

The critics tend to avoid what Murray insists is central to "Losing Ground," and that is a moral rather than an economic argument. Post-1964 transfer programs are bad, Murray says, because 1)they reward the undeserving poor and dishonor the poor who struggle to make thir own way, and 2)they are built on and tend to propagate the false ide that "poverty was not the fault of the individual but of the system."

For Murray this is wrong factually, because poverty was falling in the 1950s, and wrong morally, because it seems to excuse individuals from responsibility for their conduct as well as for their fate. He shows, rather carefully, I think, how the idea of blaming the system developed naturally out of the civil rights movement and then was carried over to the related but rather different issue of poverty.

What Murray doesn't show and what his critics tend to ignore is that the idea of blaming the system has lately been in serious decline. As evidence, consider the rhetoric of Jesse Jackson, who perfunctorily calls for government programs to lift "the ships off the bottom" but who speaks with genuine passion when he tells youngsters that they should work and not shirk.

Murray's hypothetical Harold and Phyllis, faced with an unplanned teen-age pregnancy, got married and worked in 1960, but stayed single and went on welfare in 1970, when, Murray contended, transfers had risen and seemed likely to keep on rising. Would they make the same decision today, when we know that benefits don't inevitably rise?

Something else has happened in the economically troubled years since 1970 to undercut the idea that the system is to blame. That is the wholly unexpected phenomenon of massive immigration. The immigrants, mostly Hispanic and Asian, are rapidly moving upward in income and are depending almost not at all on welfare. Their example shows that success is possible even for people who may be victims of some discrimination.

Americans, including black Americans, seem to be embracing the idea Murray wants to promote -- the idea that the system is basically fair and that people who work have a fair chance to earn a decent living. Some of Murray's critics may regard this as "blaming the victim," but few if any would argue any longer that it's sensible for a poor person to depend entirely on transfer programs for a living.

Just as the 1983 education reports recommended reforms that already had been enacted in dozens of states and hundreds of school districts, so "Losing Ground" urges changes in economic incentives and moral attitudes that have already been occurring. Transfer programs aren't being abolished, but their growth has been halted and not just momentarily. The idea that the individual rather than the system is to blame for poverty has new strength. Just as academic politics are so vicious because the stakes are so small, the debate over "Losing Ground" may be so fierce because it's now an argument less about the future than the past.