Cleveland's 12th ward, in a special election to replace the late councilman Joseph Kowalski, has elected the city's former mayor, Dennis Kucinich; he had 4,120 votes to 3,210 for one Edward Rybka. This would not be of much interest to anyone outside the Cleveland city limits but for the fact that Mr. Kucinich, at age 36, has already had a colorful political career--and one that tells us a good bit about the politics of the 1970s.

He was first elected to the Cleveland council in 1969, at age 23, by a 16-vote margin. In 1972, he nearly beat a Republican congressman, although the incumbent had 18 years of service and most of the district was in the suburbs. Two years later--all the while holding his council seat--Mr. Kucinich ran for the congressional seat again, this time as an independent, and managed the considerable feat of nearly beating both the Republican and the Democrat. His election as mayor in 1977, which elevated him to national notice at age 31, was thus only the latest episode in an already lengthy and turbulent political career.

Turbulent--because Mr. Kucinich campaigned indefatigably as the champion of the little guy against the big powers. He inveighed against the leaders of Cleveland's big businesses and big unions. He orated against Republican leaders and Democrats. He opposed black politicians and white. As mayor he got into a protracted battle with the city's banks and utilities. Political romantics, very few of whom can be found in Cleveland, saw him as an urban populist. As a council member or congressional candidate, he was a successful politician. But as mayor his appeal wore thin. It became plain not only that the city was going bankrupt, but also that the mayor and his youthful appointees were unable to maintain city services. For all the populist rhetoric, Mr. Kucinich was unable to deliver.

He did, however, have one significant achievement before he was defeated for reelection in 1979. He came to office in a city whose politics for 10 years was racially polarized. Elections were contests between white voters on the west side and black voters on the east, and no one had any confidence in the good intentions of those on the other side of the Cuyahoga River. Mr. Kucinich changed that. After only a year as mayor, he was vigorously opposed by a majority of black voters and a majority of whites.

Mr. Kucinich is part of a generation that entered politics at a young age and won early successes denouncing the powers that be. He seems little interested in any other kind of work, though he has written an as yet unpublished novel. He is now just one of 21 members of the Cleveland council, whose leaders are unremittingly hostile to him. In another era, he might have just been starting, at age 36, what in all likelihood would have remained a political career of little import outside the 12th ward. But the negative mood of the 1970s gave him his chance, and he showed the nation the full negative potential of a politics strong on protest and weak on just about everything else.