Voltaire, an undocumented alien philosopher, once called the 18th century Holy Roman Empire "neither holy, nor Roman, nor an empire." The recent news that the secretary of the Treasury, alarmed by federal deficits approaching $200 billion a year, is considering a third tax increase in a year when unemployment has continued to grow reminded one Democrat of Voltaire.

This Democrat suggested that the Reagan economic recovery program, characterized by tax cuts and tax increases on top of unbalanced budgets and unbroken recession, doesn't look much like what would be called economic, a recovery or a program. Or even much like Ronald Reagan for that matter.

But still, in spite of the bleakness of the economy, Reagan continues to confound his Democratic critics by looking a lot like a favorite in 1984. What Reagan is not could help partially explain why he continues to command considerable popular support. Ronald Reagan is not (a) a frowning martyr, (b) a crepe-hanging pessimist or (c) a nagging critic of the United States. Some recent Democratic candidates have been occasionally all three, which put them very much out of step with American voters.

The frowning martyr, a most unappealing type, is the joyless politician who insists that he is not a politician and would prefer to be translating sonnets from the original Portuguese.

While Reagan, reluctant to change what worked so well in his original 1966 California campaign, still bills himself as a "citizen-politician," he does it with so little public self-sacrificing, and so much good disposition that he gets away with it. The president seems to enjoy who he is and what he's doing, an attitude that most people generally prefer over that of the long-suffering drudge.

Most Americans are optimists who like America. The can't-do approach is distinctly un-American. In the '60s and '70s liberals, who for the most part were Democrats, pushed hard for government intervention to cure or alleviate disease, poverty, ignorance, injustice and pollution.

Once the case was made and the feds intervened, then in order to maintain what they judged to be the appropriate level of federal activity, liberals felt obliged to continue to remake the original case. Bad situations became worse in the retelling, and real progress had to be minimized or denied. Always the task that remained to be completed was portrayed as overwhelming. And discouraging.

Reagan, no fan of increased governmental activity, understood that Americans are proud of what we have accomplished. The American experience, contrary to some Democratic thinking, neither began nor ended with the fall of Saigon in 1975. The United States, with precious little political help from conservative thinkers or activists of the time, did save Europe, first from Hitler and then from economic collapse.

If the 1984 Democratic candidates can believably, and without embarrassment, speak of patriotism and national optimism and occasionally even indicate that they like their work, then who knows? One of them might even defeat Ronald Reagan, if he runs.