Every close election produces a long list of theories explaining why it turned out as it did.

Most are made plausible by the closeness of the vote. If there isn't much difference between the totals received by two candidates, reversal of any one of a number of adverse campaign factors might be enough to make a victor out of the vanquished.

Last week's primary election in which former Lt. Gov. Henry E. Howell was nominated as the Democratic candidate for governor of Virginia over former Attorney General Andrew P. Miller qualified as closed. Howell won by 13,612 votes out of 493,820 cast, a margin of 2.8 per cent.

Despite the narrow difference, however, there is surprising unanimity among campaign officials in Virginia on why Howell won.

There is general agreement that Howell and his staff, while conducting what appeared to be a stumbling, money-starved campaign, very efficiently achieved their pre-campaign goal. That goal was to:

Locate and turn out the hard core of Howell support built up during three previous statewide elections.

Avoid heavy handed campaigning that would drive to the polis the conservative anti-Howell vote also built up in those three statewide races.

There is equally wide agreement that Miller and his staff, while conducting what appeared to be a smooth, well-financed campaign, failed completely to achieve their pre-campaign goal.

Their primary objective was to produce a large turnout by convincing moderate-conservative Virginia voters who have drifted away from the Democratic Party in the last 10 years that Miller was a reason for them to come back and help pick a party nominee.

The failure of the campaign was painfully clear in the turnout. Less than one-fourth of the state's 2 million registered voters took part in the Democratic primary. The Miller campaigners had set a turnout goal of one-third, or about 635,000, and thought by election day they had succeeded.

They had not and the results bore out their predictions of more thana year ago. At that time, Miller campaign director Walter A. Marston said in an interview, "The problem we have lost the habit of voting in a Democratic primary. We have to bring them out. If the turnout falls below 500,000, we will be in serious trouble."

Howell campaign director Paul Goldman was equally aware of the effect that a high voter turnout would have and was confident that it would be small enough for an efficent delivery of the loyal Howell supporters to carry the day.

Months before the election, Goldman siad of Howell's Democratic gubernational primary loss in 1969 and his loss as an Independent to Republican Mills E. Godwin in the 1973 election for governor, "Henry's problem in the past was not turning out his vote. That's not going to happen this time. You're going to see the most efficent election day delivery of a candidate's vote ever in Virginia."

In another interview with three reporters months before the election, Goldman laid out what proved to be a very accurate prediction ofthe turnout. His forecasts for each of the 10 congressional districts totaled 506,000, only 2.6 per cent higher than the actual vote. His prediction of Howell's statewide margin then was 20,900, slightly high and perhaps influenced by a manager's wishful thinking.

Despite Goldman's spectaclar success, he and Howell had differences durig the campaign and Goldman resigned on Monday to resume work on his PhD in political science. Howell's chief fundraiser, William L. Rosendahl, has replaced Goldman as head of the campaign staff.

Goldman said in a post-election interview that the Howell telephone bank operation made about 100,000 completed calls to voters during the campaign, identified 40,000 favorable Howell votes and then turned out 10,000 to 15,000 who would have stayed at home on election day if left alone. That was about the margin of the Howell victory.

"They literally drove them to polls with those calls," and official in another campaign said. "They called them once to tell them to vote and then they called back to see if they had."

In addition to the voters who responded to phone calls, another 10,000 to 15,000 black voters went to the polls who might have stayed at home if it had not been for the efficient use of "flushers" and "drivers," Goldman said.

Goldman acknowledges the importance of phone banks and poll workers in turning out Howell's hard core support, which he put at 180,000 in a primary. However, he insists that Howell's position on issues, especially his opposition to a general tax increase during the next four years also made a major contribution to his victory.

Goldman believes his candidate's no-tax-increase stand projected him as a fiscal conservative despite his past proposals for various tax increase and became a major factor in adding 70,000 votes to hi s 180,000 vote base.

Beyong adding votes, he said, it h elped keep at home perhaps 50,000 potential anti-Howell voters, conservatives who in Goldman's words said to themselves, "Maybe Henry's not all that bad."

To support his theory on the tax issue, Goldman points to a Washington Post election day survey of 1,700 voters statewide. It showed that out of all voters, six out of 10 thought Howell could do a better job of keeping taxes down.

Goldman aso credits the press, including this reporter, for contributing to the turnout. By dutifully recording the small crowds, the unmet fund raising goals and the absence of political endorsements that seemed to overwhelm Howell, the press helped put the anti-Howell vote to sleep and build an unrealistic confidence in the Miller headquarters.

So deep did the Miller confidence run in the last weeks that a "don't rock the boat" attitude took over the campaign. When Howell, two weeks before the election, suggested to a Jewish audience that Miller had courted anti-Semitic support, the Miller campaign staff deliberated and decided to let Howell carry the burden of the charge unanswered.

Howell quickly proclaimed that Miller was not a bigot and suggested his remarks had been misinterpreted. Miller's failure to score his opponent's charge as intemperate and unbecoming of a gubernatorial candidate is seen by some now as a last missed chance to boost the anti-Howell vote.

Miller manager Marston readily acknowledged in a post-primary interview that the Miller campaign deliberately refrained from making an issue of their often controversial opponent for fear of alienating the Howell faithful who would be needed for a Democratic victory in the fall.

Critics of the Miller campaign also say that it spent too much money on a large staff and too much energy bringing off successful public events when it should have been concentrating on identification and persuasion of those likely to vote in the primary.

Marston's answer is that the campaign had to begin before the primary to put together an organization that could do battle with the state's well-financed Republican Party in the fall.

Marston agreed that the widespread perception that the Miller campaign was a success and the Howell campaign a failure contributed to the final out-come by inducing a slackening of effort throughout the Miller organization.

It was a campaign, he said, in which the carrot was the quest for the nomination on a tide of votes from people who had drifted away from the party and the stick was the fear that Howell's hard core fo support would dominate a light turnout.

"The carrot was always there," Marston said, "but somewhere along the way a lot of our people lost their fear of the stick."