IT CAN COME as no surprise that the administration is putting into practice its own clearly stated policy on human rights. The latest instance is the lifting of American objections to certain development loans to Argentina, Chile, Uruguay and Paraguay, police states all. These objections had not actually blocked any loans. Development presumably has the potential to benefit the common people, and the whole idea of penalizing them for offenses committed by their (unchosen) leaders is troublesome. Still, the objections had signified American concern for human rights, and their lifting will be widely taken as signifying just the reverse.

Is that fair? It probably is. The chief difficulty lies in the blanket nature of the decision, which brushes past local complexities and treats all four affected countries as though they were the same. They are not. In Argentina, for instance, notwithstanding Jacobo Timerman's indictment of the regime, the actual brutalizing of people has notably declined. That's partly because of the regime's success in killing or intimidating authentic terrorists and other perceived enemies, and partly because of its desire to normalize civil and international relations. None of the 10,000-plus people who "disappeared" in the 1970s has been accounted for. But the February arrest -- unusual in itself -- of six human rights leaders, many with "disappeared" children, prompted an international outcry that led to their release.

In Chile, on the other hand, two American doctors have just reported that as recently as May, for having treated the victims of government-sponsored torture, three Chilean doctors were arrested, isolated for weeks, blindfolded and forced to listen to the screams of other prisoners. The Americans found a "significant increase" in rights violations, with a new emphasis on psychological terror, since the Chilean constitution came into effect in March.

The administration believes that "quiet diplomacy" is the appropriate and exclusive way to soften the conduct of friendly governments on rights. What remains to be seen, however, is not merely whether this approach will be effective but whether it will be seriously tried. Wiping four different Latin slates clean at one swipe does not build confidence in either the administration's discrimination or its intent.

The question also remains open of what tools Mr. Reagan has that would let him influence the Soviet Union's human rights conduct, for the situation there is bleak. Some 47 members of the Helsinki Watch Groups have now been imprisoned, with an average sentence of seven years in labor camp and five years in exile. The Working Commission to Investigate the Use of Psychiatry for Political Purposes has been broken with the recent sentencing of psychiatrist Anatoly Koragin; he established that a Ukrainian engineer who had complained of unsafe mining conditions did not belong in the hospital where he had been interred. Also sentenced was Alexander Brailovsky, organizer and host of the Moscow Sunday Seminars, where scientists and mathematicians denied emigration visas meet to work in their fields.

All this is happening just as the support tendered to Soviet scientists by their Western counterparts is starting to wobble. Last year 8,000 scientists from 44 countries pledged to suspend scientific ties for human rights purposes; the U.S. National Academy of Sciences twice voted six-month suspensions. With Ronald Reagan in office, however, some scientists are coming to feel that contacts broken to help human rights should be knit up in an effort to restore momentum toward arms control.

This is a bad idea. Suspending exchanges to help Soviet scientists is a sharp instrument as well suited as any to its intended purpose. Resuming exchanges to promote arms control is a blunt instrument quite unsuited for its purpose. Human rights was never meant to be a governmental preserve.Citizens have always had a critical role. This is no time for any important group of Americans to drop out.