SUDDENLY IT'S fashionable to be cynical. Or at least to discern a rising tide of cynicism among the American public. Just over a decade ago, even President Carter couldn't bring it off. When he complained that a "malaise" was afflicting the American public, he was dismissed as a whiner; and the next thing we knew it was Morning in America.

But now the sun has set on Reagan-era optimism, and there is some evidence that the glow may have faded entirely: First, shoot-from-the-lip maverick John Silber won the Democratic gubernatorial primary in Masschusetts. One time zone away, voters in Oklahoma were gleefully approving an initiative limiting state legislator's terms. Then came a new national poll sponsored by the Times Mirror Foundation that claimed to show an increase in cynicism, findings that appeared to give context and theoretical structure to the Massachusetts and Oklahoma votes.

And thus the Cynicism Boomlet -- a thousand points of gloom -- was born.

Don't buy it. At least not yet. These seductive claims are based largely on a few carefully arranged facts and lots of vivid imagination.

Opinion polls extending back into the 1950s show that cynicism toward politics, politicians and government isn't new. By most measures, America's Age of Cynicism is at least two decades old and counting. Nor is the public demonstrably more cynical now than it was a few years ago. Just the contrary seems to be true: The national mood is decidedly more upbeat today than it was in the late 1970s, when confidence in government and politics was at its post-World War II nadir.

The data suggest, in fact, that arguments for a resurgent cynicism are not so much wrong as distracting. Some public pulse-takers like pollster Mervin Field in California claim that "contented apathy," not cynicism, is diluting our politics.

"It's not so much distrust of government as the sense that government's irrelevant, a distancing between citizens and the government" said Gregory Markus, professor of political science at the University of Michigan.

The case for increased cynicism rests on three wobbly legs.

Consider first those Oklahoma and Massachusetts Miracles. Admittedly, any national movement that spanned those two states would have to be broad-based. But the facts suggest that something other than the New Cynicism propelled these votes.

Take the term-limit vote -- please. "Anybody who's seen the Oklahoma legislature in action knows why that was a winner," quipped Harrison Hickman, a Washington-based political consultant.

But easy laughs aside, the term-limit vote reflects sentiments that are decades old. Gallup polls since the mid-1950s have found that far more Americans favor than oppose limiting the terms of members of the House and Senate. Since the mid-1970s, six out of 10 persons questioned by Gallup consistently favor 12-year limits for House and Senate members, percentages that have remained essentially unchanged through the 1980s.

"Limits have been popular with the public for years," said Thomas Mann, director of political studies at the Brookings Institution. "Mann's law is that any referendum on any form of direct democracy will pass. A national primary would pass right now, and would have passed 20 years ago." Nor can one build much of a case for increased cynicism on the basis of the Democratic primary results in Massachusetts, where turnout exceeded even the most optimistic forecasts. While Silber's victory embarrassed the state's political press corps and pollsters, it came as no surprise to others who poured over pre-election polls in the state. And what they saw was almost a complete rejection of the regime of Michael Dukakis and, by implication, the party establishment's candidate, former attorney general Francis X. Bellotti.

"Looking at the survey data, it was hard to imagine Silber losing," said Everett Ladd, director of the Roper Center for Public Opinion and a political science professor at the University of Connecticut, who has studied those Massachusetts pre-election surveys.

"It wasn't cynicism," Hickman said. "It merely proved that voters in Massachusetts were exasperated with Michael Dukakis and his ilk."

It's even hard to mount much of an argument on the basis of recent primaries to suggest that the electorate is in a particularly anti-incumbent mood this election season. After all, a total of 404 of the 405 House incumbents running this year won their primary elections. Finally, hold up a mirror to the Times Mirror study, which many newspapers headlined as detecting "growing cynicism" among Americans based on a comparison between the foundation's 1987 and 1990 polls.

The evidence for such a claim, however, is something short of compelling. In 1990 the Times Mirror study group characterized 35 percent of the electorate as having strongly anti-government views, compared with 33 percent three years ago. In terms of expressed willingness to vote and interest in national affairs, 48 percent were judged to be at the top end of the scale, compared with 47 percent three years ago.

One- and two-point changes? Those differences are statistically insignificant and substantively meaningless.

True, the percentage of those characterized in the Times Mirror study as being the most politically alienated increased from 37 to 42 percent. This modest jump is intriguing and perhaps the early warning of growing public dissatisfaction. But at this point, two polls do not a trend make, particularly since "touchy-feely" questions designed to detect alienation and apathy are notorious for producing quicksilver changes in either direction, depending on the headlines of the day.

In fact, other major surveys suggest that Americans are significantly less cynical and alienated than they were 10 or even 15 years ago. In 1973, for example, 83 percent of those questioned in the University of Chicago's annual General Social Survey (GSS) said they had at least some confidence in Congress, a favorite institutional whipping boy.

By 1980, that figure had bottomed out at 62 percent. But it gradually rose during the 1980s, reaching 73 percent in April of this year. "At least in the last three years, there's been no clear sign of a trend," said Tom Smith, director of the GSS. Confidence in the presidency also shows the same general trend. The percentage expressing at least some confidence in the executive branch fell from 79 percent in 1973 (the first year of the GSS) to 62 percent in 1980 and has hovered around the 70-percent mark since the mid-1980s.

Significantly, the GSS data show that confidence in nearly all institutions followed the same general pattern: A collapse during the 1970s, recovery in the 1980s -- suggesting, if anything, a modest rebirth (or at least a temporary repair) of confidence in institutions, political or otherwise, during the past decade.

"After a whole decade of unfortunate, disrupting events from Watergate to Vietnam to the oil shocks, you had a public truly doubting the quality and capacities of their institutions -- a real crisis in confidence," said Ladd of the Roper Center. "I don't see any comparable structure of opinion now."

Nor has the GSS picked up any significant increase in cynicism toward government. Nearly every year since 1973 the GSS has asked random samples of Americans whether they agreed or disagreed with the following statement: "Most public officials are not really interested in the problems of the average man." Responses, Smith said, have averaged between 66 and 70 percent throughout the 1980s.

The University of Michigan's National Election Study discloses a similar pattern. The 1988 data -- the most recent available -- show that the percentage responding favorably to a question asking how much they "trust the federal government in Washington to do what is right" was at levels similar to those recorded before 1974.

Those results don't imply that people aren't cynical about politicians and about government -- they are. Certainly the fact that two out of three Americans believes that most public officials aren't interested in the average person is a profoundly disturbing message.

"The Times Mirror folks may have overemphasized a new trend in cynicism," said Markus. "Their analysis there was overstated. But at the same time, I would not at all conclude that things are just fine." After all, "a majority of Americans don't trust their government. I don't find that a very happy equilibrium. Remember, there was a time just a few decades ago when big majorities of the people expressed great confidence in government."

(In fact, National Election studies through the mid-1960s consistently found that more than six out of 10 said they trusted government to do the right thing at least most of the time; four out of 10 held a similar view in 1988.)

The latest numbers carry a decidedly downbeat message, but one that was much louder 10 years ago than it is today. One difference between then and now, some students of politics and public opinion suggest, is that the political and social elites are more attentive to change.

"This new concern about cynicism in government is fundamentally an elite, not a mass phenomenon," said Mann of the Brookings Institution. "The public has long been cynical and distrustful." What may be developing, others fear, is something superficially more benign than cynicism but ultimately just as fatal to the nation's political health.

"There's been a withdrawal and disengagement in the process," said California pollster Mervin Field. "It's manifested by fewer and fewer people voting. We have also seen that people are becoming a little more politically passive, an apathy that might be described as contented apathy. That's a little different than alienation. It's the view that government's just not where it's at."

Others say conditions are ripe for a free-fall of confidence similar to that which occurred in the 1970s. That's because they see sharp parallels between conditions today and the forces that drove confidence down 20 years ago. Then, cynicism grew as political debacle piled on economic disaster: Watergate, the oil embargo, Vietnam, the 1974 recession, the hostage situation in Iran.

Similarly, America now faces the uncertain prospects of a shooting war in the Mideast, disruption of oil supplies, the S & L scandal and an economy headed toward recession.

"We have the potential in the making for another period of downward movement," said Arthur Miller, professor of political science at the University of Iowa who has written extensively on the decline of public support for government during 1970s. "If you look at attitudes, we're right about where we were in 1972-73."

Richard Morin is director of polling for The Washington Post.