The question of "tax reform" may not seem crucial these days in a time of recession and a threatened energy shortage, but that in itself may serve to illustrate a point.

The fact that one of the great political issues of the 1960s has been all but forgotten now seems as good a measure as any of how much the American scene has changed.

Ten years ago, there was no question what "tax reform" was about -- or, for that matter, why it was "needed." Tax "reform" meant closing the "loopholes" that benefitted the rich.

The tax code provided for dozens of tax shelters that allowed high- income persons to escape taxes by offsetting their earnings with artificial "paper" losses.

If you could eliminate these so called "loopholes," you could lower income tax rates for everyone, the theory went. The result would be a simpler -- and more equitable -- system.

"It was 'Get the corporations and the Rockefellers,'" muses Thomas Reese, former lobbyist for Tax Analysts and Advocates, a "tax reform" group with admittedly dwindling support.

"Anyone with a $100,000 house," he says.

But in the past several years, the issue has become more muddled. For one thing, economists no longer agree on what constitutes genuine "tax reform."

Some still want to broaden the tax base. But others seek far different goals -- replacing the income tax with a consumption tax, or providing new investment incentives.

Even the vocabulary has changed. The very term "tax reform" now is surrounded by quotation marks, in recognition that it means different things to everyone.

And the onetime epithet of "loophole" now is reserved for unintended inadequacies in the law. A tax writeoff that benefits specific groups is called a "preference."

At the same time, the number of special tax breaks has proliferated. There are "tax incentives" on the books for home insulation and pollution control equipment alike,

Most spectacularly, the wide-spread political support for "tax reform" that seemed so alive in the late 1960s appears to have vanished in recent years.

President Carter's effort last year to push through a big "tax reform" bill actually boomeranged on the White House.

Instead, Carter was forced to accept a major reduction in capital gains taxes -- the opposite of what "reformers" had sought.

And organizations such as Taxation With Representation," a group set up in the early 1970s to lobby for "tax refor," are having trouble getting money to survive.

Why is "tax reform" in such deep trouble?

Well, at least part of the current weakness stems from the movements fleeting -- but still significant -- success in the early and mid 1970s.

In 1975 and 1976, for example, Congress pushed through major legislation that helped limit some of those earlier "loopholes" by restricing the use of so-called "paper losses."

A few of these changes now are in danger of being reversed. But many of the most-criticized abuses have been stopped. So some "progress" has been made.

Second, the movement of "tax reform" to the legislative forefront in the 1970s served to join the issue to reality -- and that, too, was a setback the "reformers" hadn't expected.

Although "tax reform" may seem politically attractive in the abstract, the reality is that voters don't really want it -- at least as proposed by the 1960s "reformers."

As both opinion polls and congressional mail have shown in recent years, voters may want their tax bills cut, but they don't want to give up existing deductions to accomplish it.

In part, it's the old Horatio Alger concept: A taxpayer may not earn enough to use the real estate tax shelter, but he wants it around just in case he hits it big.

Carter found that out the hard way in 1978. First, he misread the mood of the electorate, promising wholesale "tax reform" when voters only wanted tax relief.

Then he bungled the legislative fight over his proposals, allowing his opponents to take over the ring.

Moreover, with income levels rising and inflation crimping further, more and more Americans now are able to take advantage of onetime "loopholes."

Some have gone even further to seek tax relief. An Internal Revenue Service study is expected to show millions of taxpayers simply have not filed returns.

What appears most likely to prevail in coming months is the reverse of what the "reformers" originally wanted -- a profusion of new tax breaks for investors and big business.

The House Ways and Means Committee is expected to include some of these in any new tax bill next year. And Carter himself may be forced to propose some.

The fact that these measures are winning support stems largely from the widespread public desire to correct the country's economic problems.

Proponents claim the new tax incentives are needed to bolster productivity and spur investment. "Tax equity" isn't even an issue. By 1960 standards, Republicans have won.

Some caution may be needed. Although some of the proposals may make sense in theory, they still are largely untested.

For example, last year's cut in capital gains taxes, hailed by proponents as a panacea, has had mixed results. Venture capital has increased, but stock prices haven't soared.

Will the old-style "tax reform" revive again? Reese, no longer with the movement, believes it will. The current lack of interest, he says, is "just a communal catching of breath."

Still, the past decade's shift recalls the admonition by Sen. Russell B. Long (D-La) that "tax reform is in the eye of the beholder."

Maybe the phrase ought to be in quotation marks after all.