JOHN BRADEMAS, the No. 3 man in the House of Representatives' leadership, has come to the conclusion that the often-tense relationship of federal money and policies to American cultural activity has reached a new and volatile phase. And to prove it, he's been going around the country asking for new answers to some old questions.

In recent weeks Brademas has chaired four of the hearings being held coast-to-coast on a proposal to put on 1979 White House culture conferences to address cultureal issues, and will oversee the final hearing here this Friday.

With Congress about to open, aren't there more pressing things for the House Majority Whip to do? After all, the arts and humanities are traditionally rather low on the Washington town pole and Rep. Brademas is quite comfortably high. He's served his Indiana district for 19 years and is chairman of one of the busiest House subcommittees. And he and his wife, Mary Ellen, have just been singled out by the publication singled out by publication "w" as members of "The Superset" of 1977 - in company with Christina Onassis, Prince Charles, Zubin Mehta and Britain Ambassador Peter Jay, among others.

The arts and humanities are getting a hefty share of his time, Brademas says, because he is convinced that the specific options available for resolving the current grants issues - to whom federal money should go, and in what amounts - have remained murky, getting insufficient dispassionate thought and analysis.

And in lieu of a White House initiative, Brademas introduced resolutions for separate White House conferences on the arts and humanities designed to sort out priorities in arts policy, serve as a forum for fresh ideas and insights, and stimulate government action.

"I don't think the administration has yet evolved a cultural policy," Brademas says bluntly.

Such conferences, attended by large numbers of persons from a broad spectrum of sources, have in the past contributed to new legislation.The 1969 conference on nutrition helped lead to nutritional labeling and a reexamination of the food-stamp program. Soon after the more recent conference on the aged a program on nutrition for the aged was passed.

If approved, the conferences would be planned and conducted by presidentially appointed National Planning Councils. The President would choose the chairmen and each would have 15 members. The resolution stipulates that the states and the endowments must assist the councils. The councils must submit a report with detailed recommendations for legislative action within 180 days of the conference.

The staff director of Brademas' Subcommittee on Select Education, Jack Duncan, estimates that the conference would cost "somewhere between $1.5 million and $2.5 million."

Passions run high on art policy these days. The President stated in his campaign that he thought cultural funds should be distributed more widely, and in March he told a search committee formed to recommend a nominate for the chairmanship of the Humanities Endowment that he wanted to rid the agency of "an elitist attitude." And Livingston L. Biddle Jr., the president's newly appointed head for arts endowment, is an advocate of greater local involvement of states and localities in distributing grant money.

Some of the critics of President Carter's appointments - including former Arts Endowment deputy director Michael Straight, Yale drama school dean Robert Brusten and historian Arthur Schlesinger Jr. - attacked this as "populism" and "politician of culture." Some also expressed fears that the federal distributors, who spent $230 million this year, would spread grant money so thin that more established individuals and organizations would be left to suffer.

Brademas does not share these fears. He rejects the "elitism vs. populism" analysis, and sees the choice as one between "excellence and access." By "access" he means reaching both more creative figures and attracting wider audiences to what is created. He agrees that on some occassions "the two will conflict and that's when the hard decisions will have to be made."

So the White House conference would have an agenda something like this, as Brademas sees it:

"Adjustment of tax laws to insure more equitable treatment of artists, composers and authors who make contributions of their works to museums and libraries. In the 94th Congress we were nearly successful in making this change."

"Consideration of the possibility that federal funds should be given to cultural institutions for daily operating expenses." Now this is done only by the new Museum Services Institute, which was put at Brademas' behest into the Department of Health, Education and Welfare instead of the Arts Endowment.He feared cultural policy was getting overcentralized in the Endowment and says "I don't like cultural bureaucracies."

"Encourage states to give more money from tax dollars to the arts and humanities."

"Consideration of whether grants should be keyed to the dollar volume of cultural institutions. This is great for the Metropolitian Opera, but is' not so good for struggling companies."

"Study of the burgeoning area of arts education. They're doing good things in the high schools and the grade schools. But I think more should be done in the universities. Too many courses are keyed just for the specialist and not enough to the generalists who will constitute future audiences."

"Discussion of further ways to stimulate private support, which is still growing along with public support."

"Take a look at unusual innovations that don't cost much money, like the program to convert abandoned railway stations into museums, or the art bank in Canada through which the government purchases works of living artist for display in public buildings."

"Explore the possibilities of (Humanities Endowment chairman) Joseph Duffey's proposal that the Endowment take the initiative in developing a public dialogue to help redefine national values."

Brademas acknowledges that this is a lot to bite off. But he feels that a lawmaker "is now in the position on these questions of not having enough information. It's like Lyndon Johnson once described the presidency, 'The problem is not so much doing what is right, as knowing what is right.'"

Brademas has strong feelings on the so-called Bibicoff Bill, which would merge the two Endowments with the Office of Education into a new agency. "It would be a serious mistake, because the Endowments would be submerged in a large bureaucracy."

So far no public opposition to a White House conference has been voiced publicly, perhaps because most of the witnesses at the hearings are hand-picked. At the New york hearing on the arts, 25 persons testified, including Mayor Koch, Gov. Byrne of New Jersey, Leonard Bernstein, Billy Taylor and John Herney.

One of the witnesses, producer Joseph Papp, said later that he thinks "such a conference will not only have tremendous impact, its positively a public responsibility." He also supports the wider dispensing of grant money. "I can't make such a big thing about the threat to quality." A lot of people who are fretting about it don't have quality themselves. The wider it's spread the greater are the odds that quality will emerge."

A witness at the Dallas hearings, playwright Preston Jones, author of "The Texas Trilogy," reflected Papp's views on both subjects. "The hearings created an enourmous amount of excitement down here. I'm on the Texas Arts Council and there's no question that we need more. Who knows which little poetry magazine we can help may not turn out to be first-rate. Of course, you have to have guidelines. You can't just give out everything to any guy who happens to have a press in his back yard."

One question mark is whether the administration will endorse the conferences. Barry Jagoda, special White House assistant, says, "There's a possibility that we might have a national arts festival and one part of it would be an intensive look at the state of the whole culture. It is something that will be taken up with the President at an appropriate time."

Conceivably, the White House position might not necessarily be the last word. Says Brademas, "You know we call these 'White House conferences' more for the status than for any other reason. They don't have to be called White House conferences."