A FUNDAMENTAL new social contract has been ratified in Poland. It exists only in outline form and has yet to be put into practice and has not passed the test of time. Yet the authorities have agreed to share power with the new union movement, and the workers have agreed to work -- not simply to suspend their strike threate but to accept their share of responsibility for the economy. Nothing like this has ever happened in a communist country.

Ostensibly, the latest dispute concerned the terms on which the Solidarity union movement would register with the government-run courts. Warning of further strikes, Solidarity had rejected the official demand that it acknowledge in its charter the leading role of the Communist Party: this would have compromised the independence that is its reason for being and the basis of its mass appeal. In a well-scripted courtroom showdown, the government then withdrew the demand that the acknowledgment be in the charter and the union offered to make it in an "annex."

Leaving the courtroom, Lech Walesa, the union leader, underlined the real trade-off: "Everyone has to go to work and work hard." This is the basis on which the Polish party and government leaders had gained conditional Soviet acquiescence in their intent to grant the union a measure of power. The authorities' argument was that the country is too poor to offer adequate pay and benefits in order to enlist alienated Polish workers in repairing the shipwrecked Polish economy -- a job that will require years of hard work and that will mean years of austerity as well. The leadership finally decided it had no choice but to offer the workers political autonomy or, to use the more discreet term, union independence, instead. It did so, by the way, in the name of honoring its longstanding (and long-ignored) commitment to the workers' rights inscribed by the International Labor Organization, a useful outfit to have around.

Real economic decentralization will also be bitterly resisted by a bureaucratic power structure already split over the wisdom of political relaxation. Such economic reform is also bound to be viewed darkly in the Kremlin and in the more Stalinist quarters of Eastern Europe. This makes it impossible for the Poles to relax: Soviet tanks could yet roll. For the moment, however, the momentous quality of events in Warsaw must be recognized. Union and official leaders alike have shown steadiness and vision. They need time and quiet to make their peaceful revolution work.