WHATEVER its contemporary interpretations, democratic liberalism in Cambridge has seldom been a passing phenomenon. With the presence of Harvard, Radcliffe, MIT and 22 other colleges and universities, any historical account of liberal leaders educated in the Cambridge area no doubt would uncover countless luminaries.

One such 20th century liberal, Thomas Phillip (Tip) O'Neill, Cambridge's U.S. Representative, recently has emerged as a nationally prominent figure. While evading the nimbus of most national politicians, last month O'Neill captured the post of House majority leader without making any enemies along the way. His success is no mystery.

At the forefront of liberal movements for 37 years, Tip O'Neill is noted, in the words of one Congressman, as "a compassionately human politician who knows the art of effectively communicating with men who are supposed to be, but seldom become, his adversaries."

If asked, most Harvard students probably could not identify 60-year-old Tip O'Neill, but they soon will become aware of his singular personality. Moving into the office of former Majority Leader Hale Boggs, (D-La.), whose plane vanished over Alaska last October, O'Neill is suddenly being thrown into the media spotlight.

It is an unfamiliar position for this affable and modest Cambridge man; he has traditionally been receptive to the press but seldom has he outwardly sought its publicity. Now in a position of high leadership, O'Neill's unpretentious attitude toward Washington's power and social structure has already pumped fresh air into the capital's current "power of the purse" controversy.

Conditioned by 37 years of legislative experience, O'Neill is beginning to provide, along with Speaker Carl Albert, the dynamic and effective leadership House Democrats have lacked in recent years. The Nixon Administration, previously unworried by House rhetoric, faces a 6 ft., 2 in. Irishman who unhesitatingly warns his collegues: "I believe that Congress has its own mandate from those people most affected by the President's budget. We will not allow President Nixon to eliminate these essential programs in the areas of adequate housing for middle America, the education of our youth, the health care of our elderly, and the general welfare of our Nation."

Not a single vote was cast against O'Neill in January when he was chosen as House majority leader--he received unanimous acclaim by House members for his "absolute fairness" and approachability. Many have identified him as the best-liked man in the House." An expert in parliamentary procedures, O'Neill has earned the respect of Democrats and Republicans alike. As Rep. Thomas Rees (D-Calif.) claimed, he is "a damn bright, shrewd, very kind man; an excellent politician with a lot of guts, a lot more open to innovation and reform than other leaders." O'Neill, in part, wins such accolades by establishing close working relationships with vast numbers of representatives and making it a point to know their first names.

RATHER than seeking publicity, O'Neill circulates behind the scenes, building upon an unquestioned record of credibility. On the House floor, he towers over his collegues, regularly providing counsel. A close working relationship has been established between Speaker Carl Albert and O'Neill: The two constantly consult on the floor and off. O'Neill is so competent in dealing with all congressmen, in fact, that he has gained a non-regional reputation. As one South Carolinan representative noted in seconding O'Neill's nomination last month: "He'll be a great leader; he knows every one of the members and has no prejudices. He knows no South, no East, no West, no North--he's All-American."

The story behind this "All-American" is deceptively simple, much like his style. The son of an Irish bricklayer, O'Neill entered politics at age 16 campaigning for Al Smith's presidential drive. At 21 he lost the race for Cambridge City Council by 150 votes. The year he graduated from Boston College, 1936, he was elected to the Massachusetts legislature where, in 1947, he became Democratic minority leader. During those years, O'Neill cultivated his talent for leadership. Once independent Democrats gravitated toward him. He was fiercely partisan and, in 1948, led his fellow Democrats to their first majority (by three votes) in Massachusetts history. O'Neill ascended to the speakership where, as Eddie Bellis, his former page, remarked, "he stood on top of the mountain as the first Democratic speaker."

From 1948-1952, O'Neill wielded a heavy gavel, physically and spiritually. "Tip probably broke more gavels than any speaker in the past 25 years," recalled State Rep. Jim Cravin. "Contrary to some speakers, Tip never let the House get out of control. He believed in the system: everyone follows the rules. He wanted good attendance records from all members." He even locked the doors during important roll calls to, as O'Neill put it, "keep a, fella from taking a walk." "As strict as he was, he displayed a good sense of humor from the chair but never went out of his way to tell jokes," Cravin said.

Harrison Chadwick, also a State Representative during O'Neill's Beacon Hill days, remembers his collegue as "an intensely partisan but friendly leader who could be at ease with any sort of group.

"Tip was quite self-sufficient when it came to making important decisions," Chadwick said. "Not that he didn't consult other members--he did. But he wasn't as dependent upon others' input as many before and after him had been. He was very proud to be the first Democratic speaker in Massachusetts. We knew that if Tip wanted to move forward in politics, he had the capability to do so.

"Perhaps most impressive is the fact that, through all his years in Washington, he has not deviated from his basic philosophical leanings. He is still an outstanding liberal who supports pro-labor and human welfare legislation. But he never latched onto one speciality as so many Congressmen do."

O'Neill's apparent lack of specialization is compensated for by his clubbiness with legislators. He has the ability to unite diverse groups of politicians into a solid mass of voting power. "And that," one Congressman stated, "is what O'Neill's politics is all about."

The Irishman's strongest trait, cultivated in the Massachusetts legislature, is the tricky ability to consistently communicate with all members of the House. Thomas O'Neill III, a freshman representative on Beacon Hill, explained his father's lasting techniques: "Dad can't stand being disliked. He's so friendly that animosity is a foreign word to him. If there's a problem between another member and him, Dad simply calls him or her up and clears up the difficulty--no hard feelings remain. He talks friend-to-friend and communicates best with members in the committee room."