IT IS IMPOSSIBLE, sometimes, to over estimate the Marxist influence in the Reagan administration. That's Groucho, of course, not Karl.

Never did what must be an inconquerable appetite for farce seem plainer than in the Foreign Relations Committee hearings on the confirmation of Kenneth Adleman as director of the Arms Control and Disarmament Agency.

The president has been in hot water on two continents since the unceremonious dumping of the previous director, Eugene Rostow, a famous hawk, who on his way out the door made the devastating charge that his crime had been to show "too much zeal" in pursuing agreement with the Soviets.

The president's solution to his credibility crisis was to make the most egregious against- the-grain appointment since he sent up Ernest Lefever, a crusader against human-rights policy, to run the Human Rights Office in the State Department.

Thirty-six year old Kenneth Adleman, a deputy of Jeane Kirkpatrick, the hard-nosed ambassador to the U.N., seems to be much more an advocate of the arms race than he is of arms control, a fact that could hardly be concealed, since he has written copiously to that effect in right-wing journals.

Reagan could have chosen a less literary nobody to occupy Rostow's desk, and enjoyed, if briefly, the benefit of the doubt. He could also have saved a lot of money. He has announced a $64-million advertising campaign to popularize his "zero option" arms proposal in restive Europe.

But the gag was too good for the White House pranksters to pass up. Never mind the German elections, which are focused on the nuclear point. It is such sport to put your thumb in the eye of the peace movement.

Adleman, a young man with ginger-colored curly hair, is much less a swaggerer in person than he is in print, where he lays about him like a l9th century British colonel whacking the natives. He seemed to be under tighter restrictions than those just imposed on our negotiator Paul Nitze, the imperious 76-year- old he will allegedly supervise. Although one of his qualifications for the job is his experience as coordinator at the U.N. disarmament session, Adleman came on as a kind of E.T., someone lonesome and afraid in a strange land.

It was if he had been living on another planet while the rest of the world had argued and raged over Reagan's nuclear policies from here to Hamburg.

Adleman had, for instance, no views about limited nuclear war -- a concept the president has not hesitated to speak about.

He had, however, already committed to paper his thought that "the U.S. should be prepared, and be seen to be prepared, to put our strategic forces into limited play in limited crises."

He had no views about whether a nuclear war is winnable or survivable -- two other notions the administration has bandied about with horrendous consequences to its "peacekeeper" image.

But he did seem to know considerable about the "slippage" in nuclear balance and was extremely forthcoming on the subject of verification. But when Sen. Rudy Boschwitz, (R-Minn.) asked him if he had ever considered the possibility of the elimination of nuclear weapons, Adleman replied reproachfully that his job was to represent the U.S. in the U.N. -- and implied it would have been unseemly for him to dwell on matters outside his jurisdiction.

Sen. Alan Cranston (D-Calif.) announced at the outset that having read Adleman there was nothing the young man could say that could "convince me to support his confirmation."

Armed with quotations, Cranston stalked him down his scrapbook. Cranston moved in for the kill with paragraphs which looked on the bright side of proliferation in South Africa. With nuclear capability, the South Africans could help out in submarine warfare and protect themselves from "ground assaults in the region."

Cranston saw in it a proposal to nuke black people. Adleman is obviously not a killer, and spoke convincingly of his interest in Africa.

Cranston, he said, should look at the other seven chapters in this particular offering, wherein the bad side of proliferation in South Africa was described. It was, he pleaded, a "contingency paper," like those from the Defense Department.

That was, of course, the problem. Adleman plainly belongs in the Pentagon, not in ACDA, where they are supposed to think of peace as a contingency.

Boschwitz, one of the less combative Republicans, was obviously distraught. He gave Cranston some of his question time, and declared grimly his desire for "extended" hearings. Boschwitz is up next time, and just can't see the humor in the administrations's side- splitting move to prove once again how "serious" it is about arms control.