ONLY TWO THINGS are immediately clear in the wake of the Supreme Court's decision Monday on the death penalty. The justices are having enormous difficulty holding the middle ground they staked out when they ruled capital punishment constitutional in some, but not all, situations. And this subject will be back before the court frequently in the years to come.

The constitutional issues with which the justices are struggling reflect familiar divisions in the national debate over capital punishment. At either extreme, the issue is simple. One side would abolish the death penalty completely; the other would put it back where it was before 1972: in the hands of legislatures, judges and juries. But if you are somwhere in the middle - wishing to preserve capital punishment but wanting to sharply limit its use - you must define the cases in which it can be imposed.

In its own approaches, the court has been somewhat circular. In 1972, it held the existing death statutes unconstitutional because they gave juries and judges so much discretion that decisions on executions had become arbitrary and irrational. Now, they have struck down Ohio's effort to meet the requirements of that decision because it gave judges and juries too little discretion.

But that's not as illogical as it sounds once you examine the facts of the cases. In 1972, the court had before it a mound of evidence that the death penalty was being used in highly discriminatory fashion: Blacks were often executed for crimes almost identical to those in which whites were only sentenced to prison. This time it had a case in which a young woman - the getaway-car driver who was in a nearby cafe eating when an attempted robbery turned into a murder - was sentenced to death, while the trigger man escaped a death sentence by pleading guilty and testifying against her. Under Ohio's law, she was equally guilty of that felony-murder and could escape a death sentence only under sharply limited circumstances or by plea-bargaining.

It's hard to know where the court is going to go next in this long procession of cases. While that is due partly to its own internal inconsistency, it also comes from the fact that a majority of the justices have yet to agree on how to handle any of these cases. The Ohio one, for example, split them five ways. Only four members voted for the chief justice's opinion that says juries must not be excluded from considering, as a factor mitigating against a death sentence, anything concerning the crime or the criminal. That view is the controlling law right now because two other justices believe all death sentences are unconstitutional.

There are, however, some indications of where the court may be headed. The votes may exist to strike down any law that makes a death sentence mandatory for a specific crime except a law that punishes a murder committed by a prisoner serving a life sentence. The votes seem to exist to eliminate capital punishment except for those convicted of actually causing someone else to die. The votes also seem to be there to limit sharply the factual circumstances under which a death sentence can be imposed but to leave unlimited the power of the jury to refuse to impose it.

Rules like these are still evolving, as the views of some of the justices. It will be some time before either is solidified, and the continuing public debate over capital punishment may have a substantial impact on their final form.