A crucial Reagan adviser

President Reagan needs to appoint a science adviser -- and not only because the office is mandated by law. Science and technology are intimately involved with the varied concerns of the President, and he will want the best advice he can get on this as on other fronts. Suggestions emanating from his staff that the science office might be downgraded and transferred out of the White House, which would requiring amending the law, are therefore cause for concern.

There are outcries from the scientific community at cutbacks in research and educational budgets that were announced without that community being consulted, as there are outcries from other communities which feel injured by the new economies. Our worry here is with a large issue -- namely, the ability of President Reagan to deal effectively with the many questions he will face in which science and technology are important factors.

Are military advocates of "Star Wars" laser weapons farsighted realists or deluded romantics? Is the Clinch River Breeder Reactor, for which funds are in the new budget, already obsolete? To what degree should efforts to make coal a dominant energy source be tempered by concern that burning it may release a harmful amount of carbon dioxide into the atmosphere and bring about a climate change? What is needed to deal with toxic waste? Is the new information technology a serious threat to privacy?

Many such questions come to the President's desk, each with a cadre of experts to argue the pros and cons. As noted by James Killian Jr., the original science adviser under President Eisenhower, given these unavoidable circumstances Mr. Reagan "will find it useful to have on call unbiased and competent technical advice from advisers totally loyal to him and skilled in working closely with the Office of Management and Budget and other White House staff members."

This is what the science adviser and the Office of Science and Technology Policy, which the adviser heads, are meant to provide. Delegating that function to other government agencies would vitiate it. Those giving advice would have loyalties divided between their agency and the White House.

All of this was gone into in detail by the Reagan transition team for science and technology. Last fall the concept seemed well understood by the incoming administration. But members of that team have had little contact with the postinaugural White House, and there are signs that senior White House, officials now wonder how to fit a science adviser into the decisionmaking process.

President Reagan and his staff should think again. The President confronts critical policy decisions that require sound technical judgment. Without a science adviser whom he can trust, he will have no assured way to include such judgment in his decisio ns.