Nelson Rockefeller is a man of vigilance ond unflinching courage. Certainly the average citizen must have this impression, for, in addition to his far-sighted shelter program, Mr. Rockefeller now urges nuclear tests in the atmosphere.

Vigorous opposition to atmospheric testing has confined itself to far-left groups and organizations which have been successfully labelled as visionary. Everyone knows that Pauling and the Society of Friends, if not pink, are at least somewhat odd. Except in such odd places as Cambridge, Massachusetts, therefore, agitation against tests has been negligible.

But the hard-thinking realists have not forgotten the lessons of history. Senator Dodd of Connecticut observed after the Soviet resumption of testing that the action proved the utter fatuity of the American moratorium. Moreover, it confirmed that Russia had been conducting tests underground all along. Although Mr. Rockefeller has not attained an equal mastery of the logic of Realpolitik, he is surely nobody's fool.

The American responsibility to all free peoples and future generations, Rockefeller maintains, "is to do, confidently and firmly, not what is popular, but what is right." "We are now clearly compelled to conduct our own nuclear tests." The basis for this clear compulsion is the existence of "a Soviet nuclear power whose extent, nature and ingenuity lie beyond our power to measure."

President Kennedy's statement authorizing preparation for atmospheric tests bears curiously little resemblance to this utterance. Kennedy places considerable emphasis upon the detailed evaluation of the Soviet tests. Testing will not resume, he asserts, unless such an evaluation indicates pressing necessity.

Conceivable objectives of surface testing include development of cheaper, more powerful, and more efficient warheads, try-outs for anti-missile missiles, and refinement of the "clean bomb." Tactical atomic weapons can be tested underground. A cursory examination of the technical factors suggests that the United States can afford to avoid surface testing.

Yet no civilian or group of civilians has the information necessary for the final decision. A staggering array of considerations confronts the President and his advisers. Not the least of course are three problems which do not admit of ready quantification for computer solution: leukemia, monstrous births, and bone cancer. Mr. Rockefeller does not mention these problems. Indeed, one has the feeling that Mr. Rockefeller does not think overmuch about them. Geneticists, after all, do not agree.

Politics is a rough-and-ready game. A strong stand against appeasement and for a tough foreign policy wins votes. Together with the military the hard-line politicians constitute a formidable pressure group. And Rockefeller's blithe rejection both of painstaking technical evaluation and agonizing soul-searching places him in the vanguard of this group.

No one can ever ascertain "clear compulsion" for either choice in a situation with the ramifications of atmospheric testing. Substantial right-wing pressure, though, may well compel Kennedy to resume tests. Such a development would be tragic, for the arguments of the politicians are as scientifically shallow as they are morally infantile. Vigilant Mr. Rockefeller has been exceedingly irresponsible.