The escalation of violence and intimidation at abortion clinics recently produced its fourth and fifth victims in Brookline, Mass., and a moral, political dilemma for leaders in the anti-abortion movement and the Catholic Church. The public should applaud their responses, which have been decisive and proper.

The most forceful, and potentially most effective action has been taken by Boston’s Cardinal Bernard Law and the region’s Catholic bishops, who sensibly called for a moratorium on demonstrations at abortion clinics.

Maine’s Bishop Joseph Gerrity was clear and eloquent in his message to Maine’s quarter-million Catholics. In asking for a moratorium, the church is not weakning its opposition to abortion, explained Bishop Gerrity, it is attempting to create an atmosphere that promotes discussion and discourages violence.

“Since few, if any, Americans see abortion as a moral good, I am optimistic that we can identify areas of common ground,” wrote Gerrity. It was a reasoned appeal for calm in what has become an irrational and volatile confrontation between extremists polarized on both ends of the issue.

Last weekend, an abortion-rights activist was arrested after threatening to blow up a Catholic Church in New York. Alice Hand, charged after making at least three telephone calls to the Sacred Heart Catholic Church, told police she was distraught over clinic shootings across the country, acts for which she partially blamed church policy.

In their shared anger, violence had been begetting violence, and both sides were becoming like their enemy. It had to stop. Cardinal Law and the bishops stepped in with their appeal.

Immediately following the December shootings in Massachusetts, a spokesman for Operation Rescue National decried the incident and spoke out against “vigilantism (which) invariably brings with it lawlessness.” That, in turn, creates a society ruled by its fears, where everyone is suspect, rights inevitably are diminished, and metal detectors at clinics or schools frisk everyone, children and the pregnant, sick and confused.

The bishops should not expect their thoughtful response to have a calming influence on extreme elements — people on the fringe rationalizing acts of random violence in the interest of life or personal freedom — but their words and suggestion are welcome and potentially soothing.

A voluntary moratorium on clinic protests, as Gov. Angus King observed Tuesday, “will give us some breathing space and lower the level of tension.” That is an atmosphere in which reasonable people of good will can work.