IN A BELFAST prison last Thursday, seven convicted terrorists of the Provisional Irish Republican Army, which wishes to expel the British from Northern Ireland and unite Ulster with the Republic of Ireland in the south, began a hunger strike. Their purpose is to compel the British to give them political status, and thereby to legitimize both their employment of terror and their cause. They belong to a group of prisoners whose previous efforts to achieve these goals -- by a "dirty protest" involving a refusal to wear prison clothing, bathe, or use toilets and by seeing to the murder of prison guards in their homes -- had failed. Hence their adoption of an extreme tactic in a familiar Irish nationalist tradition, a hunger strike (with water but no food). Along toward Christmas, their ordeal will likely produce a fresh rash of terrorist acts by IRA sympathizers and a crescendo of public compassion, unless the British government caves.

There you are. In analogous circumstances in 1972, another Tory government granted these prisoners a special status, which was withdrawn in 1976. To head off this new hunger strike or at least to appear reasonable on the eve of it, the current prime minister, Margaret Thatcher, last month granted all prisoners (not just terrorists) a right to wear civilian clothing. Her gesture drew defiance from the IRA, and she is now taking the line that nothing less than the authority of the state is at stake. In this she is entirely right. The seven strikers were convicted, by due process, of real crimes of death and violence. To make political concessions to them under emotional blackmail would be to invite further challenges -- by Protestant as well as Catholic terrorists. To try to nullify the strikers' considered decision, by forced-feeding, would also be a victory for the IRA.

The strike is bound to start looming large in the American consciousness as Christmas nears. Calls will come, from troubled Irish-Americans, IRA sympathizers and humanitarians, to have the British do something. Americans as a whole need to understand, however, as a good member of Irish-Mericans already do, that what is involved is an assault on the very tissue of authority by which any government is sustained. Mrs. Thatcher, we judge, does not need to be advised to defend the integrity of British power. The contribution Americans can make is to encourage her to proceed further along the path of exploring political alternatives in Ulster. The change required is certainly not the one born of violence, sure to produce violence, espoused by the IRA. It is one that will enlist the Catholic minority as well as the Protestant majority in building a stabel democratic society. The IRA's latest campaign cannot be allowed to deflect the Thatcher government from pursuit of this goal.