OSTENSIBLY THE FIGHT in Poland between the government and the independent union movement is over the length of the work week, but everyone understand that actually it is over power. The government, citing the country's desperate economic straits, wants more Saturday work, and the union, citing the needs of the workers, wants less. The government is reluctant to accept negotiation as the method of working out such questions, which are endless, since negotiation is a method that calls its authority into question. That is, of course, why the union insists on negotiation. It is a brutally difficult situation and over it hangs the threat not simply of a civil war within Poland but also of a Soviet-sponsored military intervention. Saturdays in Poland have become political climaxes -- yesterday was certainly not the last. Every day that Poland's experiment in democratizing communism survives, the threat increases.

Until now, the Kremlin has taken the position that the crisis is primarily the Polish Communist Party's to resolve. It has sought to deal carrots (credits) sticks (mobilization on Poland's borders) to the Polish comrades to enable them to handle it. It cannot be said of these oficials that they are intrinisically less worthy than the strike leaders who have so captured Western opinion. They are required to demonstrate enough loyalty to Polish nationalism to earn the trust or at least the begrudging tolerance of Poles, and enough respect for Soviet interests, which in this instance are consistent with Polish interest, to keep the Soviet army off Poland' back. Their lot would be infinitely easier if the workers, while they argued, would go back to work and work hard, but working slowly or withholding their work are the laborers' only political tools. Both the official and union leaderships seem fully aware of the ironies that have interlocked their fates.

The new factor in the Polish equation is Ronald Reagan. Probably nothing he can say or do in this period of building crisis will make nearly so much difference as the impression the international community already has of him. It is an impression, we think, of someone who cares deeply about the right of the Polish people to claim their freedom and who denies in his heart any right of the Soviet state to affect Poland's destiny. Nor is he so committed to detente or to the old idea of spheres of influence that he would check his ardor for Polish freedom on either count.

his is not to say that President Reagan might do something violent or rash if Moscow invaded. Rather, an invasion would likely confirm him in his already evident inclination to take the most serious steps of which the United States is capable to contain Soviet power acros the board. Few Americans would be inclined to argue with him.