The Italian Communists contend, and many other people agree, that only they can save the country now. But how would they go about it, exactly?

The case of the late Andreotti government doesn't augur well. Though born of necessity, that is not what it died of. It was killed off deliberately when Communist leaders realized that even so modest a venture in collusion with the establishment was playing havoc with their party.

The Andreotti experiment lasted 17 months. A minority Christian Democratic Cabinet, in a Parliament with no workable majority, it came into being when the Communists agreed not to vote against it and passed away when they decided not to go on not voting against it. (The smaller liberal, Republican, Social Democratic and Socialist parties did the same, but counted incomparably less.)

What made the Communists suddenly junk a government getting more done than most, whose elaborate six-party program they had helped to draft and warmly endorsed barely five months before, became disturbingly clear only after the event. What they said made them do it was a national emergency so bad that Italy could no longer be governed without them. As a consequence, Italy is no longer being governed at all. In a deadlock that could last for months, several urgent reforms have been frozen mid-way through their parliamentary passsage: a comprehensive medical-care and health law, which Italians have dreamed of for years, a fair rent law they've been dreaming of since the war; and a bill giving the police special powers to cope with terrorist violence - which the Communists had approved in the six-party program and have kept bottled up in parliamentary committee ever since. Predictably, meanwhile, the emergency goes on getting worse.

Though Italy is not quite so desperately close to a crackup as some interested parties make out, it is certainly in a lot of trouble. It has the highest incidence of political terrorism in the world, the highest inflation in Europe (though reduced by a quarter last year) and the highest number of unemployed in Europe (1.6 million, three-quarters of them under 30). It owes $20 billion abroad, while its budget deficit has doubled in a year to over $30 billion. Its productivity is half, and labor costs per unit double, the Common Market average. It is nevertheless the only industrial nation where real wages went up 7 percent last year, on top of a 25 percent automatic, indexed increase to keep up with living costs. The majority of its larger factories are operating at half capacity, while forbidden by law and the unions to lay off workers with nothing to do. And many or most state-controlled industries would go under tomorrow if not for prodigal state handouts.

These are terrible problems, but they certainly can't all be blamed on Andreotti's government. Political terrorism, from the extreme left especially, is if anything directed more virulently against the Communists themselves than the ruling Christian Democrats. Nine-tenths of the yawning state deficit is caused by inflated state payrolls and pensions, constantly swelling on the insistence of heavily Communist-influenced trade unions. Grotesque distortions in the economy are only partly the result of 30 years under Christian Democratic misrule; the other part is the fault of a rigidly protectionist unionized workers' caste, taking care of its own at the expense of the taxpayers, the backward south and the unemployed.

Yet throughout these 17 months, the Communists (and Socialists, to be fair) have demonstrably dragged their feet on effective antiterrorist measures. Communist leaders have promised a medium-term blueprint to restructure the economy, only to come up with a 120-page instant-happiness brochure that deserved no attention and got none. The six-party program, in which they had a very large voice, indeed promised terrific reforms of practically everything in the distant future, but thoughtfully avoided mentioning a single neuralgic issue affecting organized labor. The Communists' most spectacular success, in those programmatic negotiations, was in talking the Christian Democrats into divvying up on power posts and patronage; in the state radio television network, in large and strategic banks, in control over welfare and credit institutions transferred from Rome to local and regional governments. The Communists' most spectacular failure, on the other hand, was in the area where they could supposedly do the most good.

Communist leaders here obviously recognize the need for something resembling Great Britain's social contract: wage restraints, mass layoffs where necessary, more work and less absenteeism in exchange for less inflation, more jobs and more social equity all around. Party labor leaders like luciano Lama have undeniably tried hard to head Italian workers in that direction.

But the fact remains that wages went up 32 percent overall last year. Implacable worker resistance keeps blocking redundancy layoffs. Bankrupt state industries keep getting bailed out at colossal cost, on the insistence of riotous workers. The state-owned Alfasud car factory, symbol of so many deluded hopes for the disinherited south, is still losing $100 million a year, while union leaders were helpless to prevent 713 wildcat ministrikes there in 1974.

Lama himself could not persuade the workers of Fiat, Italy's biggest private industry and foreign currency earner, to put in six Saturdays of overtime to fill a huge export order this winter. Nor could be dissuade 200,000 metalworkers from marching on Rome last November with demands that no Italian government could meet in times like these. It was when Lama also failed to prevent a call for a nationwide general strike, issued by the whole confederation of Catholic, Social Democratic, Republican, Socialist and Communist unions, that the Communist Party changed overnight from the Andreotti government's friend and ally to its executioner.

The blunt truth is that, in this first experimental stage on the way to full Catholic-Communist collaboration - Enrico Berlinguer's historic compromise - the Communists could not do what they claim they alone can do: deliver the working class. Their efforts so far have met with sullen or openly outraged resistance on the shop floor, alienated left-twing students and run into such hard-eyed criticism from Stalinist old-timers (and not such old-timers) inside the party that Berlinguer, its general secretary, was forced into sensational retreat.

To allay bitter suspicion of a sellout in these quarters, Berlinguer is insisting peremptorily now on a jump from the very first to the very last stage of his proposed historic compromise: direct Communist participation in the government. Acceptance so soon of an ultimatum so imperious, from a party whose shady past is still a vivid memory and whose recent performance has been less than convincing, by a traditionally ruling Christian Democratic Party with an explicit electoral mandate to the contrary, might well tear that ruling party to pieces. Maybe that would save Berlinguer, but would it save the country?