The most ingenious explanation, to date, of why we should not conclude an arms treaty with the Soviets has been offered, fittingly, by the new director of the Arms Control and Disarmament Agency, Kenneth L. Adelman.

Making his debut before a Senate subcommittee hearing on disarmament to plug for President Reagan's proposal to open a branch office of the arms race in outer space, Adelman said that an accord, without proper verification, "could create problems for future presidents."

Although he said patronizingly that the approach of Sen. Paul E. Tsongas (D-Mass.), which is to make verification part of the bargaining process, may be "a logically coherent position," Adelman solemnly warned that an arms control agreement could lead to "friction" between the superpowers.

How there could be more friction than there is now he was not asked to define. Adelman's knowledge of, and commitment to, arms control is sketchy at best, but senators, many of whom voted for his confirmation because they were told that he basically would have nothing to do with policy, accept his airy rationalizations without dispute.

He is adept at political persiflage, and has learned to massage senatorial egos with respectful references to their printed and spoken words. In his case, they settle for an absence of abrasiveness.

Preposterous notions like Adelman's do not go unchallenged elsewhere. Sensible people are saying sensible things, even if the White House turns a deaf ear.

George F. Kennan, who has spent 55 years of his life studying and observing the Soviets, put his finger on the root of the problem of no progress: the "grotesquely overdrawn" official U.S. view of the Soviets.

Soviet-American relations are in "what can only be called a dreadful and dangerous state," he told a luncheon meeting of the the American Committee on East-West Accord.

He made some comments about the Soviets, which may have caused heartburn to Soviet Ambassador Anatoliy Dobrynin, who was at the head table. Kennan touched on their most unattractive characteristics, their "positively neurotic passion for secrecy," their Third World meddling, their harsh treatment of dissident citizens.

But we must talk to them, he said, because "at the end of our present path of unlimited military confrontation lies no visible destination but failure and horror."

But the president does not consult the likes of Kennan as he forges ahead with MX and "Star Wars."

At his news conference the president added a little fuel to the fire of the "suspicion, antagonism and cynicism" that Kennan said somberly smolders in the attitudes of both sides. He voiced again his "very great suspicion" that the Soviets are cheating on the treaties, in effect. He could not prove it, he said, but he obviously wanted to make a contribution to the atmosphere at the newly reconvened START talks in Geneva.

When embarking on "Star Wars," his "dream" defense against the nuclear threat, he called in Dr. Edward Teller. Teller is one of the few bomb makers who has not repented his presence at the creation of the atomic age. The rest of the scientific community is opposed.

A trio representing the Union of Concerned Scientists followed Adelman to the stand to call for a moratorium on testing anti-satellite weapons. They advocate what Reagan is most averse to, that is, negotiating with the Soviets, something Fred C. Ikle, undersecretary of defense for policy, says is not in the cards.

The opponents, who testified, with a wealth of technological detail, that "Star Wars" would merely "up the ante in the deadly poker game," included retired Adm. Noel Gayler, former director of the National Security Agency.

He likened the anti-satellite shield as a remedy for nuclear war to Laetrile: "people want to believe in something hopeful."

Ikle, who is conspicuously more knowledgeable than Adelman, could not answer two key questions put to him by Tsongas. He ducked when the senator asked how many of 6,000 missiles launched by the Soviets would get through the shield.

And he had no reply to a weary query about the arms race: "Where is the end of all this?"

The answer is, of course, nowhere, as long as the commander-in-chief consults his anti-Soviet obsessions instead of the authorities, as long as he convinces Congress that the Soviets are more dangerous than nuclear war and as long as he hires people not for their knowledge but for their ingenuity in coming up with excuses for why we cannot have an arms control treaty with the Soviets.