Tonight's vice-presidential debate is the occasion of no Throttlebottom jokes. Gone is the time when vice-presidential running mates were picked for ticket-balancing alone and then exiled beyond the White House veranda. Jimmy Carter raised the institutional role of the veep by making Walter Mondale his understudy in all major responsibilities. Ronald Reagan, before enlisting the experienced George Bush, tried first to recruit the even more credentialed Gerald Ford, a former President no less, for a dual leadership role; Mr. Bush, too, has been drafted into the decision process.
The historical case for the importance of the vice-presidential candidate is obvious. In this century alone five vice-presidents have suddenly succeeded to the Oval Office: Theodore Roosevelt, Calvin Coolidge, Harry Truman, Lyndon Johnson, and Gerald Ford. Presidents incapacitated for a period included Woodrow Wilson and Dwight Eisenhower. Two Presidents were assassinated; the incumbent President was wounded. The succession argument has unfortunately been revived by President Reagan's Louisville debate performance, which lacked an anticipated clarity and forcefulness.
Fairly or not, George Bush will be sized up as much tonight as a potential White House successor as he will be compared with rival Geraldine Ferraro. Could Mr. Bush be counted on to follow through on the Reagan administration's economic , arms control, and foreign relations policies? History also shows that vice-presidents, as quickly as protocol allows, begin to remake policy in their own image. This is only right. They must be prepared to assume the full power as well as the full responsibility of the nation's highest office. So Americans will have to look through the expectable Bush defense of Reagan policies for the political and character core of George Bush himself. As a moderate Republican senator, sizing up Bush's presidential prospects, puts it: ''We still don't know who George Bush is. He has to declare himself.'' Admittedly this is difficult for a loyal vice-president to do. It wasn't until possibly Sunday night's debate that Walter Mondale began to crack free of the deferential secondary role associated in the public's thinking with his Carter administration years.
For Representative Ferraro, tonight's debate is at least as momentous. Her first political aim will be to prolong the hope of a second look at the ticket by American voters occasioned by the Louisville debate. She too will be judged as a possible successor to the Oval Office. With many Americans not yet ready to accept a woman as vice-president, this process of imagining Ms. Ferraro as president must penetrate even more layers of prior conceptions about women's roles in public life that simply do not exist for a male. It is not to be missed that tonight's debate occurs on the centennial of Eleanor Roosevelt's birth. How far women have come from Eleanor and Franklin's era, when a woman at best could aspire to wide political influence by the force of her own character and the circumstance of marriage, but not through direct elective authority!
In an era when women's progress in legal, social, occupational, and personal terms is of major political consequence, Ms. Ferraro's appearance on the vice-presidential debate platform is itself a breakthrough. Some might appreciate it and some not; but for the first time a woman will be challenged, on an equal and direct footing with a man, to articulate how her administration would confront economic, foreign, and domestic issues. Ms. Ferraro, correctly, has thus far been given no special treatment for being a woman; her grilling over her personal finances attests to that. Her performance, if anything, will be scrutinized even more closely than Mr. Bush's.
Tonight the vice-presidential candidates, as debaters, will be on their own. The possibility that one of them will have to succeed prematurely to the Oval Office argues for them to drop the defensive conventions of surrogates and reveal what kind of chief executives they would be.