IT IS NO LONGER specially daring to say, as Robert Shogan does as the basic premise of his book, that the presidency as an institution does not work very well.

Already in 1980 there was abundant reason to worry about the prospects for the presidency. Kennedy, Johnson, Nixon, Ford and Carter had already been frustrated by the poor connections between the White House and the rest of the political system. Not only had each of these five men failed to achieve the changes they believed necessary -- changes they had promised the American people in their election campaigns that they would carry through. Three of the last four all failed to achieve what is presumably any president's minimum aim -- reelection. And Nixon failed to survive his second term.

In 1980, however, it was possible to say, "Yes, but it will all be different for Ronald Reagan. Conservatives devoutly believed that the problems of the presidency flowed from the activist conception of the office it was endowed with by Franklin Roosevelt, and from the liberal ideology in whose service the activist presidency was recruited. Even Nixon and Ford, in this view, were tarred with the brush of that idea of the presidency. Ronald Reagan would change all that because what he was going to do was to reduce the role of government and in so doing cut the presidency back to size. It was not only card-carrying conservatives who believed this, either. To a great extent Washington observers and the media generally were persuaded that the problems of the presidency were only the problems of an outdated liberal theory of the office, or at least that Ronald Reagan would be able to use the powers of the presidency to carry through a radically different conservative program in economics, foreign policy and in the whole style of government.

The Reagan administration is only just now coming up to the halfway mark, and already it is plain that those hopes were an illusion. To put it at its simplest, Ronald Reagan has discovered that it takes just as much power to reduce the power of government as to expand it, and that cutting the budget may be as far beyond the president's power as increasing it.

By 1985, when Ronald Reagan's successor is moving into the White House and setting out to implement the promises he has made to the electorate, it will be a quarter of a century at least, and arguably 40 years, since a president has been able to make the institution work either to his own satisfaction or to the extent necessary to satisfy the American people's expectations. Nine presidents, from Truman to Reagan, one after another, will have complained about the frustrations of the office, and they will have been right. Each in succession has failed to carry out a substantial proportion of the agenda he had set himself.

Shogan's analysis of the nature of the problem is crisp rather than profound. The combined experience of the last six presidents, he argues, "suggests that the chronic failings of the presidency overshadow differences in the previous experience of presidents. The White House is gripped by a syndrome whose symptoms are manifest in the record of the past 20 years. They are evidence of an affliction which has less to do with personal characteristics, upon which so much attention is lavished and upon which Carter placed so much stress, and more and more to do with the political and governing system to which presidents must respond."

The body of his book is in effect a narrative political history of the past 20 years from a presidential perspective. It is written at a racing gallop; some important episodes are compressed into a few sentences, but no important incident has been left out, and Shogan has a shrewd eye for the motives of the players and a sharp sense of the irony and the incidental comedy of what is essentially a tragical history.

The themes he pulls out of this story are familiar: the decline of party, the rise of personal politics, the increasing dominance of guerrilla operators on the White House staff over the regular machinery of government.

The subtitle of the book defines its theme as "Why Presidents Fail and What Can Be Done About It." It is hardly fair to blame a writer for the claims made on his behalf by blurb writers and those who compose copy for book jackets. Yet it has to be said that Shogan is far better at describing what has gone wrong than at suggesting what might be done about it.

I am full of sympathy for him. The task of diagnosis is usually easier than the cure. In this case, so many contributory themes, both in the way the American political culture has evolved, and in the needs and expectations of society, have combined to produce the present difficulties, that it is hard to find a platform to stand on in order to lever the system back into its groove.

Yet the criticism has to stand. Robert Shogan has written a useful, even elegant history of presidential politics from John F. Kennedy to Ronald Reagan. He has not succeeded to anything like the same degree either in analyzing the causes, nor in proposing convincing remedies, for the inadequacies of the presidency.