IT IS A SAD THING to see Thailand floundering like a scow in a storm. The reasons for its now-chronic instability are not hard to find. Under the stresses of war and modernization, the power of the military and its civilian business partners grew apace. Thus was the governing elite progressively removed from contact with the rest of the country's real needs and put inot a position to make or unmake governments practically at will. The students, representing an undeniable moral face, forced out the military in 1973. But the ill-prepared and weak civilian governments that followed could not run Thailand effectively, and civilian government itself fell victim to a coup a year ago. Just the other day the officers who had made that coup deposed their chosen civilian figureheads and installed one of their own, Defense Minister Sangad Chaloryu. as nominally the No. 1 man.

Adm. Sangad at once assured his 42 million countrymen that his purpose is to return to democracy expeditiously, and meanwhile to rule more liberally. The new "Revolutinary Group" aims for elections next year. But how does a country like Thailand return to democracy? Actually, "return" is a misleading word. In "modern" times, the Thais have not known democracy in anything resembling a Western sense for more than a few uneasy years at a time. There have been a dozen constitutions since 1932.

At different times, including, one hopes, right now, the United States has urged democratic ways upon the Thais. But in fact the postwar thrust of American policy, deepened rather than begun during the Vietnam war, has been to enlist Thailand in an anti-Communist alliance. The practical effect of this policy was to strengthen precisely those elememts in Thai society least devoted to representative government. Though the Indochina wars have ended the anti-Communist edge of American policy in the region has been dulled, the countries of Southeast Asia still must cope internally with the stresses generated in the postwar period. To salute Adm. Sangad's intentions, therefore, is not to be sanguine about his capacity to put them into effect.