THE Israelis and President Bush have each, in their separate arenas, pointed the way toward a whole new approach to the struggle between adversaries. Don't laugh - yet. The idea is for one side in a conflict to choose who will represent its opponents.Maybe the Israelis deserve the most credit for this extraordinary innovation. More than a decade has passed since they first insisted on the right to choose who will - and won't - represent the Palestinians in negotiations with Israel. This device so greatly increases the prospects for agreement that it's a wonder humanity did not happen upon it sooner! Evidence for the diffusion of this political innovation is found in President Bush's nomination of Clarence Thomas to succeed Thurgood Marshall on the Supreme Court. Learning from the Israeli example, President Bush - leader of a party that since Lincoln's day has alienated 95 percent of American blacks - has chosen, as the person to fill the "black" seat on the court, one of the few blacks who is not disgusted by the Republican handling of civil rights matters. Once this right is extended to both sides - as the logic of "rights" suggests it will - its capacity to revolutionize human affairs will become manifest. When the Palestinians chosen by the Israelis sit down to negotiate with the Israelis chosen by the Palestinians, one can imagine that sparks will fly, with each side demanding that the other be given control over the disputed territories. But the possibility of a mediated solution will be greater than under the old system, where each wants for itself all that it can get. Perhaps it would be agreeable to all, for example, to confer on some third party - such as the unfortunate Kurds or Armenians - soverei gnty over the lands. American blacks would willingly acquiesce in the appointment of a Justice Thomas, knowing that, after they choose who will occupy the eight "white" seats on the Court, Thomas would be the lone dissenter in a series of decisions upholding affirmative action and set-asides. The spread of this approach to the world of sports will also be interesting. Golf scores will be higher, as competitors choose clubs for each other, and are forced to drive off tees with their putters. No-hitters in baseball will be rarer, for at the first sign that a pitcher may be on his way to achieving one, the opposing manager will stride out to the mound to yank him from the game. One of the most interesting arenas to watch will be American presidential politics. In the new system, only registered Republicans will be allowed to vote in Democratic primaries and, conversely, only Democrats will participate in the choice of the Republican nominee. I suspect, in fact, that this new system was inaugurated in 1988. It's well known that Mr. Bush was the Republican that the Democrats most wanted to run against. It appears they succeeded in achieving their aim, but underestimated the cleverness of the Republicans, who managed to find, in Michael Dukakis, a candidate whose idea of counterpunching was Ali's rope-a-dope, but with his arms at his sides. Looking to 1992, the Democrats will certainly pick Dan Quayle to head the Republican ticket. This would leave the Republicans in an almost impossible situation. Perhaps their only hope would be that our relationship with the Japanese will deteriorate so much that we'll have to let them pick our president.