During the three weeks since the blackout, mayoral candidate Mario Cuomo has been asking a question that probes to the core of this city's sickness: Was the police force restrained by a no-shoot order when the lights went out July 14?

There has been no answer from city hall or police headquarters. Cuomo's questions have received little publicity or notice, typical of forgivable inattention as seven Democratic candidates work toward the Sept. 6 primary. Yet the answer is important: Yes, police were under orders not to use force against looters.

While not advocating bloodshed, Cuomo criticizes the city for the lack of any plan to protect private property. Inexcusable absenteeism by police officers aggravated failure to provide a back-up force of state police or national guardsmen. But Mayor Abraham Beame, seeking reelection, points with pride to the handling of the blackout amid his journeys to Washington in quest of more federal money.

The blackout disaster typifies what ails the nation's premier city: mismanagement at city hall, indiscipline and demoralization among city employees, the reflexive call for help from Washington. The events here July 14 tend to justify the Ford and Carter administrations' telling New York to heal its self-inflicted wounds.

Furthermore, the blackout looting has made crime prevention not only the top issue in the mayoralty campaign but the only real issue. Considering the fear induced by psychopathic killer "Son of Sam", ploiticians agree that the voters of the city are interested only in officeholders who can protect lives and property.

That may be why the early big lead enjoyed by ex-Rep. Bella Abzug, the candidate of the left, is disappearing. Although Mayor Beame's feisty attacks on Consolidated Edison's performance in the blackout gained desperately needed support, he has leveled off again. The beneficiaries would seem to be Secretary of State Cuomo and Rep. Edward Koch.

Koch, once considered a stereotyped Manhattan liberal, now calls for capital punishment and attacks "the nuts on the left who dump on middle-class values." His television commercials have stressed law and order, a line echoed by Cuomo in his newest TV spots. But the 32 per cent undecided vote shown by one private pollster a month before election day suggests Koch and Cuomo are not convincing the electorate, either.

The way the blackout was handled indicates why. Objective outside sources with close police connections say 8,000 officers failed to show for emergency duty that night. The principal stated reason: Low morale and even lower sense of duty that infect the city's workers despite high pay and lavish pensions.

Perhaps another reason for the no-shows was the standing order against the use of force. While a bloody shoot-out was avoided, there were no provisions for water guns, rubber bullets or other non-lethal crowd-control devices. Nor was there a mobilization plan for the national guard or state police to quickly provide a depth of uniformed officers that might have deterred looting.

The result was a bulesque of law enforcement that led to this often repeated farce: Badly outnumbered police would chase looters from a store; once the police moved on, the looters would return to strip the store. So Cuomo strikes a responsive note when he calls the city's corrosive problem "a growing expectation of impunity by lawbreakers operating on the principle that crime does pay."

A New York Times editorial following the blackout talked about "rage" stemming from "the problems of race and poverty." In fact, the real rage here three weeks later exists among ordinary people - black and white - who perceive their government as unable to make sure that crime does not pay. They see no civil-rights issue in rampaging blacks' with criminal records ignoring "soul brother" signs in the windows of black-owned businesses.

The "rage" of the ordinary people has trouble relating to a typically unenlightened campaign for mayor of New York. Beame tells unconvinced listeners that the city is on the way up again. Even less credibly, Abzurg promises she has the key to the federal treasury. Commercials show Koch flailing away at all opponents and Cuomo talking about his Italian immigrant father's grocery store.

The people, Cuomo told us are "past cynicism." But besides cynicism, there is naked fear here that the looters may reassert their impunity some ordinary evening at sunset without waiting for a power blackout. If any candidate actually convinces the city that such crime will not pay, he will be elected mayor with a vote having the elements of a public mandate.