THERE ARE DAYS -- Friday was one -- when nature does in fact seem to imitating art, art being, in this case, the old "Saturday Night Live." We have in mind what must be the most preposterous news of the century: "A Senate subcommittee yesterday, decided, by a 3-to-2 party-line vote, that human life begins at conception . . . " Well, we thought, thank God the five of them finally made up their minds. What greater authorities could one ask for on this matter, after all than the members of the subcommittee on the separation of powers of the U.S. Senate? And what more appropriate way to decide such an issue than by an up or down vote of five politicians? As the fellow said, only in America.

It did occur to us that there is a certain contradiction in the position of those who have been advocating such a finding by the U.S. Congress. For in those few hours of the day when they are not seeking to guarantee that the human fetus will enjoy all the legal rights of a human being, they are seeking to guarantee that human beings will enjoy as few rights as possible.This lobby is not exactly what you would call a great civil, human or legal rights crowd. They may be terrific on getting you born. But once you're born it seems as though the first thing they want to do is unplug your television and lift your passport.

The legislative vehicle of this theological finding is something that has been nicknamed the human life bill. It is the handiwork of Sen. John East of North Carolina who was sent here by the Lord (we decided this by a 4-to-3 vote) to make Sen. Jesse Helms look liberal. His bill is intended to circumvent the Supreme Court's 1973 finding that a variety of anti-abortion laws then existing were not constitutional. It is terrible legislation, and even some of those who favor a constitutional amendment banning abortion think so. What is good about it is that it serves as an illustration of how absolutely out of line -- how far beyond their competence, expertise and authority -- America's secular politicians are getting in their efforts to make law on this question.

That brings us to what may have been the second silliest, most inappropriate and off-the-mark argument of the week: that concerning the abortion-credentials -- we can think of no other way to put it -- of Sandra Day O'Connor to serve on the Supreme Court. Consistency does not seem to be an excessive burden on those fighting her on these grounds. First it is argued that what is wanted in a Supreme Court justice is, above all, a penchant for merely interpreting and applying the law, as distinct from making it; in the next breath it is earnestly argued that Mrs. O'Connor should be made to commit herself to a policy position on abortion; this last, of course, has everything to do with making law and much less to do with application or interpretation or the rest of that modes mandate that goes by the name of strict consructionism.

We cannot say that the anti-anti-abortion forces, commenting on this, have been a lot more helpful.The whole argument is askew, about the wrong thing -- too much on political result, not enough on how and why that result was reached. It avails little insight into the woman's qualifications, thinking or prospective temper as a jurist. Her so-called "pro-abortion" choices in the past may well have represented a very conservative (i.e., strict constructionist) reading of the law at issue and of the permissible reach of politicians. Tell us whether that's liberal or conservative, pro- or anti-abortion, good or bad for human life.

We think Mr. Reagan has probably got himself a conservative jurist. Maybe it's time for some redefinitions here.Will someone please explain how this currently noisy, politically weird and truly far-out group of people pressing for ever more involvement by an all-powerful state in American citizens' private lives and private choices got to be called "conservative" in the first place?