Eleven weeks from now we Americans will troop off to the polls to choose between two political parties and between rival aspirants for the highest offices in our land.
We are all reasonably familiar with what is involved in the choice between parties. By and large and with plenty of exceptions the Republicans tend to be more concerned with the interests of the business and industrial communities than with the interests of the people on the payrolls of those communities. By and large and with plenty of exceptions the Democrats tend to sponsor the interests of those on the payrolls.
When we then turn to the rival aspirants for the top office, president of the United States, our choice is complicated by the fact that Ronald Reagan and Walter Mondale are not really running for the same job. Yes, each wants to be ''president of the United States'' over the next four years. But the office means one thing to Mr. Reagan and another to Mr. Mondale.
We have now had over three years of Mr. Reagan in the White House. We are accustomed to his way of running the job. We have learned that he is a man of strong convictions about taxes, about what is good or bad for the American economy, about defense and about foreign policy.
We know from experience, therefore, that if reelected, he will continue to keep taxes on income, both personal and corporate, as low as Congress will permit; that he will restrain spending on welfare as much as Congress will permit; that he will spend as much as Congress will allow on defense, and that he will continue to preach the doctrine of original sin in the Soviet system, but will continue to sell to it as much wheat as it will accept.
But we also know that these general points of view in Mr. Reagan's thinking will be put into action by people on the White House staff who, while not anonymous, are nevertheless relatively shadowy people.
We know one is named Baker and another Deaver. There is an Edwin Meese whose transfer to the Department of Justice has been held up. There is someone named McFarlane who presides over foreign policy and David Stockman who runs the budget office.
But who among these subordinates is primus inter pares?
Mr. Reagan is a successful and popular head of state. He presides with dignity and ease at public functions. He says the right things at Memorial Day services, at parades for visiting dignitaries, at any White House reception for any visiting delegation. But he leaves the daily running of the business of the office to his staff.
Some presidents try to be both head of state and head of government, not always successfully. Jimmy Carter was the most conscientious of presidents. He studied every detail of the most complex problems of government. He did as little as he could of the ceremonial chores.
Dwight Eisenhower was a Reagan-type President, and a successful one. He talked about the possibility of separating the two jobs - head of state and head of government. During the first part of his term he left the detailed business of government to his chief of staff, Sherman Adams. Mr. Adams came close to being a prime minister.
If in November we vote for Mr. Reagan, we will be voting a well-tested head of state. But who will be our prime minister?
On the other hand if we vote for Mr. Mondale we can be confident that we will get him as our de facto prime minister. He can also do the ceremonial jobs, but not with the ease and enjoyment that we get from Mr. Reagan. We will be voting for a man who will primarily be concentrating on running the government.
Most countries separate the two jobs. One of the main advantages of separation is that it is easier to get rid of an unsatisfactory prime minister when there is a king or queen at the top to provide continuity. The British get rid of prime ministers when they like, by a vote of no confidence in the House of Commons.
One disadvantage of the American system is that we may find ourselves voting for a king when what we want is a prime minister, or vice versa.