If the Supreme Court has been inconsistent on the question of affirmative action, maybe it is because the members are struggling to bring theoretical justice and actual justice into the same tent.

Last week the court heard arguments on two new cases that won't make its struggle any easier. One involves the Cleveland Fire Department, which is operating under a consent decree establishing a four-year plan to increase the number of minority officers on the force to between 10 and 25 percent. The plan grew out of a suit brought in 1980, when the department had fewer than 5 percent blacks in a city that is 47 percent black. The city admitted "a long history of discrimination against minority persons" in the fire department. White officers say the plan, which allows the promotion of some minority officers who score lower on the promotion exam than some whites who are not promoted, discriminates against them.

In the second case, involving a New York local of the Sheet Metal Workers Union, the local had managed to remain all-white for decades (in an area whose work force is 29 percent black and Hispanic) by limiting apprenticeships to friends and relatives of members. The union resisted two court-ordered plans to bring its minority membership up to 29 percent over a six-year period, and balked at a requirement to keep records to demonstrate how well it was doing in meeting that goal.

The problem for the Supreme Court is whether it is possible to deal with racial discrimination, whether admitted out of court or proven in court, without recourse to numbers -- and whether the use of numbers, as hiring goals, discriminates against whites. The Justice Department says the court has already answered in the negative with its ruling in the case of the Memphis fire department. But that case involved not hiring but layoffs, and what the court said was that the department could not ignore seniority in order to save the jobs of recently hired blacks. In other words, the court was forced to choose between two conflicting principles.

And not for the first time. In the 1978 Bakke case, the court ruled against a rigid set-aside of medical school seats for blacks -- a quota. But in the Weber case, the following year, it said it was all right for an employer with a disproportionately white work force to establish a special training program with half of its positions reserved for blacks.

In short, the court has been trying hard, in difficult circumstances, to do justice. The Reagan Justice Department won't even acknowledge there is a problem. Attorney General Edwin Meese, reversing years of pro-affirmative-action policy, argues that hiring goals must inevitably become quotas and quotas ae unconstitutional because they discriminate against innocent white men. He contends that the only constitutional remedy is to find the individuals who were discriminated against and devise a means for making them whole. Meese and his assistant attorney general, William Bradford Reynolds, seem not to care that the pressing problem of bias in America is not discrimination against white men. Their sense of racial justice is wholly theoretical, even when the result is demonstrable discrimination against minorities. They call it "colorblindness," and tout it as a virtue.

I am inclined to another view, espoused by Justice Harry A. Blackmun, who, in a 1978 opinion, wrote: "In order to get beyond racism, we must first take account of race. There is no other way. And in order to treat some persons equally, we must treat them differently."