Hamburg has become ''governable'' again. But West Germany as a whole may become ''ungovernable'' next March.
This is the lesson politicians are drawing from the Dec. 19 election that returned the Social Democrats to their traditional majority in the nation's major port.
The Social Democrats - thanks to energetic campaigning by Hamburg citizen and ex-Chancellor Helmut Schmidt, and incipient public disappointment with the 11 -week-old conservative federal government - made impressive gains of 8.6 percent over the last election last June to get 51.3 percent of the vote and a clear majority with 64 seats in the city council.
With this surprise victory, Mayor Klaus von Dohnanyi will no longer have to conduct the arduous negotiations (which eventually failed) for acquiescence in his policies on the part of the counter-culture Greens.
The conservative Christian Democrats dropped from their plurality position of last June to 38.6 percent and 48 seats, losing a disappointing 4.6 percent of the vote.
The Greens - the half protest movement, half political party of anti-nuclear environmentalists - lost 0.9 percent of its previous votes, for a total 6.8 percent and eight seats. The Greens thereby lost the swing vote or spoiler role it gained with its initial election to the city council last June - a phenomenon that quickly got dubbed ''ungovernability,'' or ''Hamburg relations.''
The small Free Democratic Party - the long-term swing-vote party at the federal level that deserted its coalition with Schmidt's Social Democrats last fall to bring in a conservative West German government for the first time in 13 years - again failed to get over the 5 percent minimum for a seat in the Hamburg city council. In a disastrous showing, it dropped 2.3 percent from the 4.9 percent of the votes it had won last June.
Paradoxically, although the election restores in Hamburg a majority government that can implement decisions, it raises the specter of minority ''ungovernability'' at the federal level.
This is so because an adjusted projection of the Hamburg vote suggests that the conservatives can't quite win a majority in the planned general election March 6; that the Free Democrats won't get enough votes for any parliamentary seats at all; and that the balance between the two minorities of the conservatives and the Social Democrats will then be held by a few Green members of Parliament as the ecologists come into the federal Bundestag for the first time.
All the parties are drawing the predictable conclusions from the Hamburg election.
The Greens see a chance of blocking the deployment of new NATO missiles scheduled to be stationed in West Germany beginning at the end of 1983 (if there is no US-Soviet arms control agreement in the interim).
The Social Democrats, elated by their large gains in both the Hessen and Hamburg state elections following their October ouster from the federal government through a coalition change, see a chance of again becoming what party chairman and ex-Chancellor Willy Brandt has called ''the decisive power'' in West Germany.
In decoded language, that would mean inducing Green MPs to tolerate a Social Democratic minority government, probably through a leftward shift of the Social Democrats.
For their part, the conservatives are focusing on warning the country's stability-loving voters against just such a ''Red-Green-chaotics'' cooperation. In the German political lexicon ''Red'' refers to leftist politicians ranging from the Social Democrats to the communists. ''Chaotics'' refers to the violent fringe at various demonstrations.
The Free Democrats are also beginning to campaign against the Greens in the wake of Hamburg. They had hoped that with time voters would forgive them for abandoning the popular Schmidt last fall. The Hamburg election, which split the party in two, makes this hope look less and less justified.
It is not yet sure the general election formally scheduled for 1984 will be advanced to next March, but most politicians expect it.