Edward Gierek appeared on Polish television Sunday night to announce some of the most far-reaching concessions ever granted by a Communist leader. They included free trade union elections, higher wages, a purge of Communist Party hard-liners in the government, and the promise of political and economic reforms.

Yet Gierek's virtual admission of Communist Party responsibility for the present unrest and the promises of sweeping reforms have failed to solve the crisis. Workers along Poland's northern Baltic Coast have refused to halt the strikes and accept promised reforms that would be overwhelming gains for other communist nations. Why?

The answer lies in Poland's postwar history, with its cycle of heady optimism and the bitter disappointment of unfulfilled hopes. During the last 35 years, Poles have become wiser, more politically mature, and above all more cynical about the rhetoric and promises of their leaders.

The result is a massive credibility problem for all politicians in Poland, the reformists included. Years of party-controlled propaganda in the mass media have backfired to such an extent that many Poles mistrust all official information.

"If we're told that something is white, we think it's black," one Warsaw office worker said. "We don't even believe the bad news nowadays. When the newspapers reported huge floods throughtout Poland many people thought it was just another trick to prepare us for another disastrous harvest."

The hopes of Poles were first raised in December 1956 when the hard-line Stalinist leadership was toppled following workers' riots in the western city of Poznan. Huge and enthusiastic demonstrations greeted the news of the return to power of Wladyslaw Gomulka, a nationalistic leader who had served in prison in the early 1950s.

Gomulka's first act was to blame the country's problems on the previous leadership. In words that have a familiar ring today, he told a mass rally. "The working class recently gave a painful lesson to the party leadership, for on that black Thursday Poznan workers said in a powerful voice: 'Enough!'

"The party tried to explain it as the work of antisocialists and provocatuers, but this was a naive explanation. The workers said the truth."

The immense popular support enjoyed by Gomulka at the start was squandered little by little as he gradually reasserted authoritarian Communist Party controls. The powers enjoyed by workers' councils, set up after the Poznan riots, were whittled away.

The backlash came in December 1970 when Gomulka was toppled by new workers' riots in the Baltic ports of Gdansk and Szczecin. It is said in Warsaw that he believed right to the end that he was still loved by the Polish people.

Gomulka was replaced by Gierek, a refreshingly open politican who had built up considerable trust and support among the coal miners and steelworkers of Silesia in the south. He blamed the riots on years of mismanagement by the Gomulka clique and promised dialogue and consultations with the people.

Now, once again, the authority of the Polish leadership has been challenged. Once again the initial reaction of the communist authorities was to explain away the unrest as fomented by "antisocialists and provocateurs."

Once again, the Polish Communist Party has been forced to admit that the workers are justified in many of their demands. Once again, some leaders have been disgraced and the new team has pleaded for a fresh start.

But, although Polish history clearly has a habit of repeating itself, it does so in a different form. This time, the striking workers are not satisfied with promises or personnel changes alone. They want institutional reforms -- and they want guarantees that they will be permanent.

The gathering cynicism of Poles toward their leaders was caught in a comment by Anna Walentynowicz, the crane operator at the Lenin Shipyard whose dismissal sparked the first strikes there Aug. 14. Reacting with reservation to the latest shakeup in the leadership, she said: "In 1956, I welcomed Gomulka with enthusiasm, but step by step we found ourselves on the brink of an abyss. I welcomed Gierek with satisfaction -- and later what? We thought [dismissed premier Edward] Babiuch would also be an improvement, but once again we were disappointed."

A Polish journalist said, "The problem for our leaders is that they have run out of scapegoats."

More than anything else, it is this mood of realism that seems to have saved Gierek. It is widely recognized that this departure would not solve anything -- and may even further alarm the Kremlin. Gierek's continued presence in the leadership serves as a reassurance to Moscow that, while the system can be reformed, the structure of the one-party state will remain.

But Gierek has been forced to share his authority with his former critics. Most prominent among them is Stefan Olszowsky, 49, who was dropped from the Polituro earlier this year and named ambassador to East Berlin. He has been given responsibility for economic reforms within the leadership and in effect ranks second to Gierek.

Appointed as a new deputy premier is Tadeusz Grabski, who was dismissed in September from his position as first party secretary in Konin region west of Warsaw. His removal was widely seen at the time, as retribution for a speech in which he pinned responsibility for economic chaos onto the party leadership.

In his speech, at a Central Committee meeting in December 1978.Grabski complained that only successes were ever discussed at party meetings and that gross inefficiency in the running of the economy was ignored. The speech was censored in the official press, but later appeared in an underground newspaper.

Grabski also criticized the huge gap between "the realities of life" -- the lines, the shortages, the corruption -- and "the rosy picture given by official prices, official information handouts, and speeches."

The inclusion of men such as Grabski and Olszowski in the new leadership -- pragmatic, talented, and relatively young -- is evidence that the Polish Communist Party is changing. The problem faced by the new leaders is to convince the Polish people that this time they are really telling the truth.