THE KIDNAPPING of Aldo Moro seems to be coming to a particularly wretched end. A message, delivered in the usual way, said that his captors had killed him and dumped his body into a lake. It is still unclear whether that pronouncement is only another hoax or ruse, but hope for Mr. Moro's safe return is fading. Five times premier of Italy, head of its governing Christian Democratic Party and candidate for president of the republic, Mr. Moro was indeed the symbol of Italy's political leadership that his captors claimed. The kidnappers, a terrorist group called the Red Brigades, held him for more than a month before announcing that they had murdered him. Their purpose was, evidently, to demonstrate the government's inability to do anything about it.

Hardly any government, except for the unabashedly authoritarian ones, has consistently effective answers to underground terrorism. Police in the United States have found themselves repeatedly embarrassed by their inability to lay hands on people implicated in major crimes of violence. In Northern Ireland, the guerrilla warfare drags on endlessly, generating nothing but new pain and tragedy. Elsewhere in Western Europe, the most spectacular outbursts of terrorism have been in the two countries - Germany and Italy - with clear memories of their uncontrolled police in the last gerneration's totalitarian regimes. Since the Munich Olympics, the German government has been working and public safety. But the Italian case is more complicated.

The Italians, as a matter of national choice, have kept their national executive weak. The police organizations are fragmented, and like all public services they suffer from political meddling. The atmosphere generated by the past two decades' industrialization - the most rapid that any major country has ever undergone - is unabated.

Mr. Moro was a central figure in the intricate negotiations by which the Communist Party was increasing its participation in the Italian government. With the Communists supporting it, there remains no significant opposition to the government within the framework of Italian parliamentary democracy. The isolation of the radicals has been paralleled by the rise in political violence.

Mr. Moro leaves his country a political legacy that is more substantial than if might look at first glance. He and his generation created a tradition of parliamentary democracy that has proved to be astonishingly tough and shock-resistant. But it has a flaw, and the flaw lies in its enduring overreaction to fascism.

Ever since World War II Italy has been governed by men who have mistrusted public emotion and, as a matter of principle, avoided any appeal to it. They remember fascism's endless demands for national sacrifice, and it has made them reluctant to call on their people for anything at all. In recent years, their parties have depended increasingly on patronage. It was not a style of government that could develop any great degree of social vision. Cabinet after Cabinet watched passively, as the great migration proceeded from southern farms to northern factories, as new sagged under the strain. It was a genuine democracy, but it was not a notably responsive one.

That is the tradition at which the Red Brigades struck. They cite the slums and debased universities, but their targets include the central idea of democracy as well. Their purpose is to create chaos, out of which revolutionary - that is, totalitarian - virtue will putatively spring. None of that, of course, will ever actually happen. To civilized people, the murder of Mr. Moro will be judged a reprehensible crime and nothing more. His contribution to Italian democracy will surely survive. But perhaps it has to be added that in the present period, his style of highly limited and restricted government, managed through silent parliamentary maneuvering, is no longer serving Italy well.