NOBODY SAID YOU had to have a sharply defined platform to run for high public office, and so far Baltimore Mayor William Donald Schaefer is proving just the opposite. For that matter, Mr. Schaefer isn't even "running" for governor, if you want to be technical -- and he does. But there is hardly anyone in the state of Maryland who doesn't know who Don Schaefer is or what office he seeks. What most people don't know -- and what Mr. Schaefer isn't sharing so far -- is what he believes he should or could do as governor if he did just happen to run. But the fact is, it doesn't seem to matter, which is all the more frustrating to his Democratic opponent, Attorney General Stephen H. Sachs. Already, noncandidate Schaefer has $1 million in a war chest and a 3-to-1 lead in the polls.

Mr. Sachs, who is modestly predicting the "greatest political upset in Maryland political history" in the Democratic primary this September, has been focusing on a traditional party coalition: minorities, women and labor. Mayor Schaefer, on the other hand, has been trying not to focus much at all. He's content to make the rounds with some generalities about economic development and education, and to let stand a generally affectionate perception of him as the man who brought Baltimore back from the dead.

"Mayor Schaefer and I represent two very different political approaches and political traditions," Mr. Sachs argues. "He comes from a tradition that values secrecy in government. . . . I come from a tradition that values the discussion and debate that really is the music of democracy." But so far, Marylanders seem to be listening more to the lighter tune of Mr. Schaefer, who openly sings the praises of business. Mr. Sachs likes to emphasize his reputation as a reformer; yet, Mr. Schaefer is not proving to be an easy target. He has been untouched, for example, by the savings and loan scandal or anything like it that might fortify the Sachs attack. For that matter, Mayor Schaefer is suggesting that the attorney general's role in the S&L troubles should be talked about more.

But is this all that Marylanders want to know before they choose a governor? Can Mayor Schaefer run from here to the State House without taking clear stands or talking specifically about how he would handle S&Ls, gun controls, social programs, the state legislature, taxes and so on? How about some early debates?