AMERICAN POLITICAL campaigns abound with semi-rational rituals. Take the case of the candidate-stranger who is expected both to admire and to kiss any proferred infant whose parents may be registered voters. Or how about the candidate in any community's Centennial Day parade? If genuinely serious about winning, the candidate had better be perched unsafely on top of the back seat of an open (American-made) convertible and be able to smile and wave without falling off.

But of all our political rituals, perhaps none is more peculiar than the custom that insists that the first ball, before every really important baseball game, be thrown out by the Holder of an Important Office or, at the very best, by a Candidate for an Important Office. In fact, most candidates do not throw baseballs very well. Many male candidates, in fact, throw like, if no one objects to sexist language, "a girl."

This year's Republican vice presidential nominee, is, in the matter of baseball, different. George Bush was the captain of his Yale baseball team. So when he is invited to throw out the first ball at an important game, before 30,000 fans and "a national television audience," then the people in the Reagan-Bush campaign accept.

That is how George Bush, Republican candidate for vice president, came to be in Williamsport, Pa., Aug. 30. The game may have been Little League (for its world series championship), but the cameras were very big league. After a difficult and trying week in which his diplomatic skills were sorely tested in the People's Republic of China, Mr. Bush must have been ready for an easy afternoon enjoying the National Pastime and having his picture taken.

One of the two finalist teams was from the central city of Tampa. Florida went Democratic in 1976, but the Republicans are confident they can carry it this year. The other finalist was -- are you ready? -- the team from Taiwan. Taiwan, which was once banned from Little League play for winning too often, went on to win its fourth straight Little League world title.

George Bush did not really require any further reminder of the island whose embrace by the leader of his ticket had turned his China trip sour. But sometimes when things are not going especially well, things do not go especially well, even if you do know how to throw a baseball.