There is a joke about flipping coins that goes like this: Heads I win, tails you lose. In Washington, the rules of that joke are about to be applied to President Reagan's Supreme Court nominations: he has picked them for their ideology, but the Senate cannot reject them for the same reason.

In nominating Antonin Scalia to be an associate justice of the Supreme Court and William Rehnquist to be the chief, Reagan chose men who share -- even exceed -- his conservative ideology and who, the actuarial tables inform us, will be around to implement it. Both men were chosen by the president right off the bat. They met, they chatted and Reagan popped the question. He interviewed no one else.

Almost immediately, the adjective du jour in newspapers was "brilliant," and certainly Scalia's and Rehnquist's credentials demand respect. But so do their ideologies, and it is that -- not just their brilliance -- that led the president to nominate them. Theirs is a conservatism without a smile and a shoeshine -- a brittle ideology that shimmers with intellectual energy but whose consequences will not be ameliorated by political considerations. They are both the Ultimate Reagan -- the Reagan, despite his daunting popularity, that the country has never quite accepted. If Reagan cannot be Reagan, then he has chosen surrogates who can.

The charge against liberals and their fellow travelers in the legal community -- judicial activists -- is that in pursuit of a particular principle they trample more worthy ones. For instance, in securing the rights of criminal defendants (the unconvicted), they are accused of ignoring the rights of the community. And there have been cases, especially when it comes to rules of evidence (the so-called exclusionary rule), where guilty people were given a walk because the police failed to dot an evidentiary "i".

But Rehnquist and, from the evidence, Scalia, too, are the mirror image of the activists they so energetically oppose. In the name of judicial restraint or its kissing cousin, states' rights, they would deny a woman the right to an abortion -- maybe even one who has been raped or whose child, as with Tay Sachs disease, is doomed to an agonizing death.

The same thing holds in other areas. In a bizarre application of his brilliance, Rehnquist once wrote a memo to Justice Robert Jackson urging him to vote against desegregation of the schools in the South. Whatever the legal theory cited, the results would have been plain: a loss of individual rights. Rehnquist has also voted to limit the rights of criminal defendants, homosexuals, blacks and women -- and even to limit their ability to argue their case in court.

Scalia is in the Rehnquist mold. In speeches, he has championed a stingy interpetation of the First Amendment, and in a libel case involving The Washington Post, he joined one other appeals court judge in a tortured opinion that would, if sustained, hobble the ability of the press to publish controversial investigative articles.

Supreme Court appointments are where the president gets to play for keeps -- where the momentary concerns of the present come to haunt the future. Yet some senators act as if it would be dirty pool to consider the ideology of the men involved and what their effect would be on the very people those senators were elected to represent. They talk as if ideology exists in a vacuum -- as if the president's presumed right to choose an ideological soul mate takes precedence over the consequences of that ideology. Sen. William Proxmire (D-Wis.), going for his own Golden Fleece award, put it this way: "What the hell, everybody's got to be something."

But that "something" has elements in it that the country, and the Congress, have time after time rejected. As the Harvard constitutional scholar Laurence Tribe has pointed out, in choosing judges the president can succeed where he has failed either by amendment (school prayer, abortion) or by legislation. Previous Senates appreciated that their obligation concerning a court nominee was not different from the one concerning legislation. Even George Washington had a nominee (John Rutledge) rejected because his political views were unacceptable to the Senate.

The brilliance of Reagan's nominees is not in dispute. But their ideology is a different matter entirely. A Senate that thinks it cannot judge them the same way the president did is playing by absurd rules. Heads Reagan wins. Tails we all lose.