To be ignorant is for the public servant an incalculable asset. It saves him from being a liar. Very rarely is an American politician called a liar, even during an election. However, very rarely does a politician address himself to an issue truthfully, especially during an election.

In point of fact, during elections truth is almost wholly abandoned, lest the campaigning pol find that his lapse into forthrightness has placed him at a horrible disadvantage. Some weeks ago in the great state of California the Republicans' candidate for the Senate made bold to admit that all is not well with our Social Security system. Worse still, he suggested a sensible cure. Since then his opponent, the eminent Edmund G. Brown Jr. from outer space, has been at his throat reproaching him for infamies too dreadful to mention.

It does not pay to speak honestly about real problems at election time; better it is to croon sweet nothings and to squawk about bugaboos.

In this year's elections, where is there a campaigning politico accurately describing a problem without shaving those details damaging to him, without enlarging those details damaging to his opponent, without promising instantaneous bliss once carried to the gubernatorial palace or whatever other high office he pursues? Wherever such a miraculous campaign is being waged, I venture the speculation that the campaign is doomed.

Today a journalist can say almost anything about a politician without ruffling feathers. He can call the pol cruel, stupid, ignominious, a co-conspirator with the rich in their efforts to impoverish the noble poor. Yet let him call a duplicitous politician a liar and suddenly the expansive First Amendment contracts. Shock vibrates through the press box. The journalist has gone too far. I am at a loss to explain this inconsistency. Possibly we are so wedded to the Eighth Commandment that the gravity of the charge silences us. On the other hand, maybe we are so far gone on moral relativism that we do not believe people actually lie, unless, of course, they are the officers of a large corporation.

Return to the campaign for the U.S. Senate in California. The Hon. Brown is a man who has shown himself capable of saying almost anything no matter how bizarre or apparently duplicitous. Yet all who have been spectators to his tawdry performances judge him a very clever fellow.

He has endorsed a constitutional amendment requiring a balanced budget. Nonetheless he favors still more federal spending on such dubious items as research and development and jobs programs. Well, is the Hon. Brown lying when he thumps for a balanced budget, or is he lying when he favors increased spending?

Can a politician actually be on both sides of an issue and remain of pure heart? Americans are uncomfortable with the question. It is easier for them to believe that the candidate is ignorant than that he is a liar.

Thus in the age of television, ignorance is an even greater asset than in the past, for on television there is so little time to scrutinize a pol's nonsensical statements.

Last week on the "Today" show Walter Mondale palmed off three beauties in the time it took me to brush my teeth. Earnestly describing Ronald Reagan's three-year, 25-percent, across-the-board tax cut as a "deep tax cut for wealthy Americans," he went on to assert that the Carter administration had bequeathed Reagan an economy that was in a state of "boom," and concluded that "we're going into a deep recession."

Judy Woodruff, who was interviewing Mondale, looked on quizzically. My guess is that she knew something was wrong, but what? How does one tell the former vice president of the United States that he has just uttered picklewash? And while Woodruff meditated, Mondale kept talking. Then there was a commercial.