America has three living ex-presidents, Jimmy Carter, Gerald Ford, and Richard Nixon. And they're all giving advice to President Reagan. They speak at a time of growing domestic and international strain, and the comments range from faintly cautionary to sharply critical.
Former President Ford, in comment to David Brinkley at Vail, Colo., Aug. 15, wondered if the Siberian gas pipeline confrontation with European allies couldn't have been avoided. Europe is currently 85 percent self-sufficient in gas but in 10 years will be only about 45 percent self-sufficient.
''It simply isn't sufficient,'' he said, ''for America to say to Europe, you shall not have the gas that is needed for your industries in the next decade.'' The United States should be firm with the Soviets, he said, but the allies have a case.
''I think the administration probably could have handled it better if they had been more forthright a year-and-a-half ago in their opposition.'' And with a little longer time, he said, the whole thing might have been avoided.
As to Mr. Reagan himself, Mr. Ford's judgment is that he is ''moving away in a number of instances from the position he took in 1980.'' He is ''recognizing that the political power of the US is more in the center and therefore he has to be less and less dependent on support from the far right.'' Rather wistfully Ford added that a new president often has a transition period: ''I became a little more realistic and I think that's the position Ronald Reagan is taking.''
Richard Nixon, in articles in the New York Times Aug. 18 and 19 was as careful as Ford not to criticize Reagan directly. But he urged the importance of America's European allies in the pipeline dispute and urged the policy of continuing negotiating with the Soviet Union. One doesn't have to be ''soft'' to communism he argued to carry on discussion. America and Russia live in the same nuclear world he noted; his attitude was admonitory and almost urgent. Earlier presidents, he said, have dealt with Moscow and achieved ''detente.''
''The Soviet Union has desperate economic problems,'' he said, but added that ''squeezing Russia economically did not work when Communists first came to power , when their problems were far worse, and it would not work now. Rather than decreasing repression it would increase it.''
The two Republican ex-presidents appear to be warning Reagan against the hard-line wing of the GOP. Nixon urged personal presidential contact with Moscow leaders at summit conferences, something Reagan so far has eschewed.
''Whatever we call it,'' he said, ''it is better than the alternatives of either sterile confrontation or nuclear conflict.''
The third living ex-president, Jimmy -Carter, recently broke his self-imposed post-1980 silence. At Atlanta Aug. 20, he attacked Interior Secretary James Watt over environmental policies in a speech to the Wilderness Society. Mr. Carter's book on his own administration comes out shortly.
The role of the three members of the exclusive Ex-Presidents' Club is now taking shape, as it has in times past in American history. Ford and Nixon, as fellow-Republicans, give a muted but somewhat ambiguous comment on Reagan's external difficulties and emphasize their international view as respected elder statesmen.
Carter, as former leader of the opposite party, is not restrained by political niceties and lashes out in his attack on a particular Reagan program. But all three members of the Ex-Presidents' Club agree on the collective responsibility of the man who presently sits in the White House, where they themselves once sat.
Carter is particularly sharp in this. He charges that Secretary Watt is despoiling the heritage of America's environment and that the latter has ''betrayed the public trust.'' But he argues that it isn't possible for a president ''to hide behind a secretary of interior or a director of the environmental protection agency or a budget director.''
Carter may have sharp criticism ahead. He charged the controversial secretary with being ''a caricature of irresponsibility.''
The Ex-Presidents' Club has its own rules. Members may be sharp in their attack. But they generally express sincere personal feelings, take a broad approach to foreign policy, and emphasize national rather than parochial views. They still hear the band playing their personal ''Hail to the Chief.''