The underlying reality of the Lance affair is betrayed by this reaction of members of the Senate Governmental Affairs Committee to Tuesday's briefing from staff investigators: They were unimpressed by the evidence but thoroughly convinced Lance is finished as budget director.

Although dominating front pages and national news programs by bringing "new" allegations against Lance to the White House on Labor Day, the committee's chairman and ranking Republican - Sens. Abraham Ribicoff and Charles Percy - had little to show their colleagues the next day. But while many senators remain dubious that Lance is guilty of any crime, all consider him beyond salvation. The Ribicoff-Percy operation, combined with the media barrage, destroyed what shadow of hope remained that Lance might yet regain his effectiveness as "deputy President."

Lance has been destroyed by pyramiding suggestions of wrongdoing without the hint of a trial. This suggests totalitarian-style justice or perhaps a throwback to an early American form. "This is Salem," one White House insider has been telling his colleagues all week, "and we burn a witch a year."

Beyond the catastrophe to Lance's personal life and damaging political impact on President Carter, this ensures severe difficulties ahead for conducting the federal government's business. Except for professional bureaucrats or college professors, can anyone come to "Salem" without the risk of becoming the next "witch"?

The process is shown in the role of Chairman Ribicoff, long noted as one of the nation's shrewdest politicans. Having defended Lance and attacked a media "smear" job against him only weeks ago, Ribicoff found himself in unusual country: opposing the liberal establishment. He purged himself abruptly with the dramatic holiday visit Monday to the White House, where he and Percy publicly implied grave new developments against Lance.

All that was new in their private report to the President, however, was a Republican staff investigator's interview in a Georgia prison. The prisoner, a bank embezzler, made unsworn and untranscribed accusations against Lance. Otherwise, the two senators rehashed newspaper stories (concentrating on Lance's questionable use of his bank's airplane) and informed the President that Lance's usefulness was no more.

Nor was the committee staff's report on Lance, given behind closed doors to the Government Affairs Committee, any more impressive. "It was pretty superficial stuff," one Democratic senator told us. "It was the kind of stuff a good lawyer on cross-examination could make mincemeat of." Another Democratic committee member said the presentation "certainly contained no grounds for prosecution."

Several senators accused the staff of "irresponsibility" for interviewing a convict - notoriously sources of self-serving misinformation - and permitting that information to leak into the press. Sen. Sam Nunn of Georgia informed his fellow committee members that the convict's lawyer was outraged by the incident and wanted to rebut his former client's accusations (providing he could get bar association clearance).

The committee agreed only by an eyelash to give Lance himself a chance to testify. It voted by only 7 to 6 not to postpone Lance's Sept. 15 testimony for weeks while presenting evidence against him. Having shifted sides with a vengeance, Ribicoff sided with most committee Republicans to delay Lance's appearance.

If Ribicoff had won, days of testimony would have built pressure for Lance's resignation, probably forcing him to quit before testifying. Even so, nobody on the committee gives Lance any hope of survival with or without early testimony. What is critical here is atmosphere, not facts. "I'd hate to be tried in a court of law like this," one committee member told us.

Lance's principal sin is described in nearly identical terms by a Senate defender as being a "man-on-the-go" and by a critic inside the administration as being a "go-go banker." In a dull summer, this was clear violation of post-Watergate morality as defined by candidate Jimmy Carter. The media campaign was certainly not opposed by a banking-business establishment, which not only tends to view Lance's corner-cutting as the way of the parvenu but also fears an anti-banker ruboff.

So much stress was put on improper use of Lance's bank-owned plane in the Ribicoff-Percy presentation to the President and in the staff presentation to the committee that senators fear businessmen who fly their company planes will steer clear of service in Washington. If so, the first criterion in finding a successor to Lance will be an absence of business experience. For Jimmy Carter - and the country - that means trouble.