THE behavior of the public opinion polls since the Republican convention bears out one fact of central importance in the 1988 American political campaign. George Bush has one tremendous advantage over his Democratic rival. This one great advantage is that he is the heir of the Reagan record and the Reagan record has given the American people an economic boom.
The fact that the economic boom is founded on the biggest debt ever accumulated in history, and that the boom is probably just at crest now, and that there may well be an unpleasant slide sometime in the future is beside the point. In politics, it is the perception of today that counts.
As of today, the boom exists. Never have so many Americans had so many jobs. And seldom has peace seemed so widespread and substantial, particularly after the long chill of ``cold war.''
If the American people were told that they had a choice between keeping things exactly as they are and trying for change, they would undoubtedly vote for keeping things as they are. The idea of trying to change today's condition has little appeal, and will continue to have little appeal until the boom bursts - if it does.
Add to the above one central fact about politics in the United States, as in most other democratic countries. Voters usually tend to vote against rather than for. For Michael Dukakis to win this election, the majority of voters must think they want, or be persuaded to think that they want, to get the Republicans out of Washington.
Right now there is little basis for a Dukakis campaign built on the old American slogan ``turn the rascals out.'' There have been rascals in the Reagan administration, but most of them have left. To most people the administration appears now to be both reasonably clean and economically successful.
All of which poses the central problem for Mr. Dukakis. He emerged on the national scene during the primaries because he was new, different, interesting. He is the first son of an immigrant family to reach the political top of his party and at a time when the proportion of first- and second-generation citizens is high.
But the novelty has worn off. People during the Republican convention took a second look at Mr. Bush and seem to have concluded that he represents continuity.
Dukakis has an uphill road. Inertia is on the side of the Republicans. As things look now, with election day two months away, Bush is probably going to win unless one of three things happens.
If there is an economic ``accident,'' or a sudden international change, or Bush does something foolish, then the calculations all change.
Dukakis cannot create an economic or foreign policy ``accident,'' or a Bush folly. He can improve his image as a competent alternative, should one of those events occur.
There are several things he could do to improve that image of being a competent alternative. He could, for one, announce his Cabinet. If for example, it had Sen. Sam Nunn of Georgia as secretary of defense, that would blunt the Republican charge that he is soft on defense.
It would also capture the headlines and probably cause Bush to make a similar move. We would then have the rivals competing in Cabinet offerings instead of competing in slurs and innuendos.
A personal note: I am going off next week for a long vacation to do some things I have never had time to do during 59 years of news reporting - to see Florence and the hill towns of Tuscany; relics of Etruscan civilization; Giotto's frescoes; the mosaics of Ravenna; Venice; and the lion of St. Mark; Palladian villas; Padua, Siena, Verona, and Vicenza; and the Italian lakes. I shall be back just in time to find out whether Dukakis has improved his image as a plausible alternative and Bush is still, or not, the beneficiary of political inertia.