For reasons that never have been satisfactorily explained, Americans have a compelling need to know what their neighbors think -- on every concceivable subject, instantaneously.

Something more than idle curiosity drives us. Business decisions and marketing strategies,, political judgments and personal actions, the goods we buy and the entertainment we're offered, all are based on what the latest national survey data tells us.

Consensus increasingly derives not from the clash of ideas in grand debate but from what the polls report. That the polls are,, by their very nature, the most fickle of weather vanes, shifting with every gust of wind, does not diminish their influence. No public official or corporate executive can afford to ignore them.

Thus, in the current efforts to sell the president's economic program as sound we are told what the people back home think. The doubters on Wall Street are urged to pay attention to the message from Main Street. A sharp difference of opinion exists between the two, it is asserted. One side represents the jaundiced cynicism of the big financiers, the other the innate wisdom or real heartland America, safely removed from the taints of Manhattan.

Actually, as Jean Kirk of the investment house of T. Rowe Price Associates Inc. in Baltimore observes, "With close to 30 million direct owners of stocks and with possibly double that number involved in mutual funds, pension funds, and retirement funds, Walls Street is Main Street."

Thus, the president defends his program at his press conference Thursday by citing an elusive shift in mood of the people. "There has been some psychological improvement,," he says, ". . . a different feeling on the part of the people themselves."

Perhaps so, but there are other indiccations of increasing divisiveness among the populace concerning the Reagan presidentcy. My evidence? Why, the polls of course.

Just four days before the president's tax and budget cuts began to take effect, George Gallup isued a somber finding. Ronald Reagan's presidency is creating a sharper degree of polarization among Americcans than did the actions of any other chief executive during the nearly half-century Gallup has been conducting national polls.

"An unusual degree of polarization in President Ronald reagan's standing with the American public has become evident," he says. "In 45 years of Gallup measurements there has never been greater disagreement between men and women, or whites and blacks on the performance of a presidential incumbent."

I have no way of scientifically confirming Gallup, but I do know that in recent weeks my own mail has strongly reflected his observation. The letters now are breaking down into two sharply different camps about Reagan. Their tone has become increasingly strident. In my experience, not since the Nixon Watergate days have people responded so emotionally to the way they see their president performing. One group falls into an all-out support-the-president category, the other into a bitter general denunciation of him. There seems to be little middle ground.

Here, for example, are two typical letters. They arrived in the same mail delivery on the day Reagan was conducting his latest press conference. Both are from women.

From Camp Springs Md.: Dear Mr. Johnson:

I don't think Reagan is nice.

He has worried old people on Social Security half to death ever since January.

Reagan is cold, callous, and mean. I voted for him, and I'm sorry.

I don't trust the man because he's a liar.

How can you cal him nice is beyond me. He's an actor's -- that's for sure -- but he is not nice.

Even Nixon did not try to starve the old and the sick.

From Palm Beach, Fla., a citizen expressing feelings of "truly patriotic Americans" upset by talk in the press that the Reagan honeymoon is over:

. . . Where is loyalty to a common cause we all should share?! The economy of our country is in serious trouble.

President Reagan wants to do something about it. . . . We need to thank God that such a good man of courage and wisdom is in the White House!

No! The honeymoon is not over. It's the nitpickers of whom we have so many, especially on TV and in the news, that have begun their divisive work. Why can't we emphasize the positive? There is a big job to do to build morale,, for we can accomplish our goal to get our feet on the ground if we really try. It's not by throwing money around like a drunken sailor. . . . Some of us are willing to sacrifice and wait hoping inflation & high interest rates and high taxes will come down.

As those words indicate (and I can cite many more just like them from throughout the country), feeling about Reagan are intensifying -- and, in my samples at least, they represent more than the familiar breakdowns showing people liking Reagan personally but doubting his political approach. But something other than the ups and downs in the popularity cycles of our latest president are at stake here, something that goes beyond constant gauging of the political winds.

Late last spring a distinguished social scientist, Prof. Robin M. Williams Jr. of Cornell, offered thoughts about changes in American society before the American Council of Life Insurance. "There is a yearning for clear and simple answers," he said, "but none of the simple solutions many people wish for today has any substantial prospect of success, and the daily and hourly news encourage our tendencies to swing between overoptimism and bleak despair. A less volatile and more realistic approach is needed, based on a longer perspective and sounder analysis."

Williams also talked about the tendency of people to believe other may be profiting from their own deprivations. "Such feelings undermine willingness to sacrifice for the common good," he said. "Altruism does not flourish when trust decreases and when we doubt that others will follow the rules of equity." The years just ahead, he predicted, are likely to bring declining levels of real income and increased calls for sacrifices for national goals. In his view, the key will be whether people believe those sacrifices are "both necessary and equitable."

I suspect Williams put his finger on one reason for the sharp polarization over Reagan. Americans certainly want their president to succeed, especially in reducing inflation and revitalizing the economy. Those are the positives. The negatives are also clear. Increasing numbers are saying they don't think their sacrifices will be borne equally by all, or that the president's over-whelming choice of social over military cuts are necessary.

Unless he can reassure them, I don't need a poll to tell me the prospect is for more divisions and struggle ahead.