When Ronald Reagan came to Washington four years ago he promised to get government off the backs of the people. This could be done he said, by strengthening the family, neighborhoods, churches, and voluntary associations - what have been called ''mediating structures.''
But before the President could sort through the maze of rules and regulations in the federal bureaucracy he sought to tame, he needed some mediating structures of his own. Already in Washington - and waiting with the people and policy ideas to advance his agenda - was the American Enterprise Institute for Public Policy Research.
Early in 1981, Treasury Secretary Donald T. Regan consulted AEI researchers on ways to stem inflation, then running at 12.4 percent. The new secretary left the institute's downtown Washington office with a briefcase full of position papers. Later, when Alan Greenspan, chairman of the President's Commission on Social Security, suggested taxing social security benefits as one way to balance the social security account, he borrowed an idea that AEI fellow Michael Levy had explored some three years earlier.
The institute is widely viewed as a leading source of conservative ideas in the United States today. Its message, articulated steadily and persuasively for more than 40 years, has been that there is a real need to slash government spending, cut regulations, and rebuild the military.
''We are committed to the idea that, if you look around the world, (you) cannot fail to be struck by the extent to which the economic success stories are to be found in nations with ... market-organized economic systems,'' says Tait Trussell, AEI's vice-president for administration.
''Some think tanks are listened to more than others,'' says Mark Green, president of the New York-based Democracy Project, an offshoot of Ralph Nader's Public Interest Research Group. Right now, says Mr. Green, AEI is one of those most listened to.
In a capital where power is measured by proximity to the White House, AEI boasts some 20 scholars and associates who now serve or have served in the Reagan administration. These include Murray L. Weidenbaum, Mr. Reagan's first chairman of the Council of Economic Advisers; Jeane J. Kirkpatrick, US ambassador to the United Nations; Michael Novak, special US representative to the UN Human Rights Conference in Geneva; Arthur F. Burns, US Ambassador to West Germany; and James C. Miller III, in the Office of Management and Budget.
The American Enterprise Institute, founded in 1943 by Lewis H. Brown, then president of the Johns-Manville Corporation, saw its initial goal as one of promoting free-market policies while examining the cost of government in taxes. At a time when Keynesian economics reigned, AEI's ideas were regarded as little more than those of a trade association.
In 1954, however, William J. Baroody Sr. took charge and made scholastic respectability the primary goal. Recruiting economists Milton Friedman (now with the Hoover Institution) and Paul W. McCracken, he watched the institute's influence grow steadily but modestly through the 1960s and '70s until, in 1977, the presidency passed to his son, William J. Baroody Jr.
Today, AEI's staff has grown to 145 in-house scholars - over whom Mr. Baroody Jr. stands like the chief executive officer of a major corporation, with final say on all personnel appointments as well as on all major policy studies. AEI also has 88 ''adjunct scholars'' at universities throughout the world - more than any other think tank - who help give the institute a perspective beyond that of Washington. The current list of ''fellows'' reads like a who's who of conservative thinkers: economist Herbert Stein, social philosopher Irving Kristol, political commentator Ben Wattenberg, and former President Gerald R. Ford among them.
With such a cast, AEI no longer just thinks about policy, it goes a long way toward making it. It gets out its private-sector message through a flood of magazine articles, pamphlets, position papers, and seminars. Besides publishing four magazines, it syndicates opinion pieces to some 75 newspapers and produces a public-affairs TV program that airs on about 400 public television stations. It is widely credited with having the best computerized mailing list in the think tank business. Free copies of its publications are sent to groups concerned with the topic under study. Each December it conducts a week-long series of seminars that unabashedly displays the institute's prestigious fellows and intellectual muscle.
AEI scholars are now working on a long-term study of the US Constitution in anticipation of the document's 200th anniversary in 1988. In conjunction, former President Ford is hosting a TV program on local PBS stations called ''The Constitution.'' In the planning is a major study of the Pacific Rim nations and economies.
With its prominence has also come an increased ability to raise funds. This year's annual budget, at $11.6 million, more than doubles AEI's 1977 figure. But the institute's twin successes - the acceptance of many of its proposals at the highest level of government and its increased fund-raising - poses a danger, says Mr. Green of the Democracy Project. When a think tank gets a track record, he says, companies with vested interests may fund it. A problem could arise, he explains, if AEI (or any other tax-exempt public-policy think tank) were to get funding from companies that have trouble with regulatory agencies. For Mr. Green , the critical question is: Would such studies be objective? ''It would be surprising for them (AEI), nearly unprecendented for them, to issue a tough criticism of American business practices,'' he concludes.
AEI officials point out, however, that as a general policy the institute does not accept money if the donors want to attach strings. Sponsors may specify an area of research, but they may not select the scholars who will conduct a study, says Mr. Trussell. ''We make sure we include a liberal voice in our seminars,'' he adds.
Dennis P. Doyle, director of AEI's education policy studies program and formerly with the more liberal Brookings Institution, says that think tanks naturally have ''an intellectual center of gravity, whether liberal or conservative.'' Whether on the right or left, he says, the purpose of a think tank is primarily to ''structure opportunities to exchange ideas.''
Mr. Trussell points out that Ralph Nader and former US Sens. Gaylord Nelson and George McGovern have all taken part in AEI seminars. In the end, he says, it is the ideas themselves - the positions taken on an issue or policy - that stand or fall on the merits of their thoughtfulness, innovativeness, and breadth of perspective. That, he says, is what accounts for the influence of a think tank.
American Enterprise Institute at a glance
Budget: $11.6 million (1983)
Funding: 34% foundations, 32% corporations, 19% corporate foundations, 5% government contracts, 3% individuals, 7% other
Ideological persuasion: Nonpartisan, moderately conservative
Concentration: International affairs (political and economic), social issues, economic issues (domestic and international), political issues