It cannot be easy for a politician to take a position that risks alienating a segment of his or her ethnic constituency. President Reagan and such other luminaries of the Irish-American community as Patrick Moynihan, ''Tip'' O'Neill, Ted Kennedy, and Hugh Carey deserve credit for courageously speaking out against the terrorist Irish Republican Army and urging their fellow Irish-Americans to seek a solution of the Northern Ireland question through peaceful not violent means.
Indeed all Americans can applaud the President's unusually strong words against ''the moral bankruptcy of the men of violence'' on the occasion of St. Patrick's Day: ''Some few, but vocal, Americans believe the differences between Irishmen can only be solved by violence and intimidation. They are no friends of Ireland. They disgrace the principles for which both Ireland and America stand.'' Amen.
Who can fail to sympathize with the yearning of many Irish-Americans that the land from which their forebears sprang be united? Yet what kind of land would it be if Ulster Protestants were incorporated into Ireland through undemocratic means and against their will? How could a nation build a unified society on the basis of the animosity and fear this would leave? Ireland may well be united one day, but surely the way must lie through a healing of mutual mistrust and a concerted effort toward accommodation. Such accommodation needs to come from both Ulster Protestants and IRA supporters.
Unfortunately, too many Irish-Americans do not think through the import of their support for the Provisional wing of the illegal IRA. When they appointed an IRA sympathizer - Michael Flannery - to be grand marshal of New York City's annual St. Patrick's Day parade, they were in effect supporting a group that not only seeks Irish unification through violence but a Marxist Ireland. It is not a democracy that IRA Provisionals want but a socialist state. When Americans contribute to the Irish Northern Aid Committee (NORAID), allegedly for help for widows and families of interned IRA members, they are actually providing machine guns, rifles, and other weapons for the IRA. Fortunately, sober voices, including those of Cardinal Cooke of New York and members of the US Congress, made clear their disapproval of Mr. Flannery and the IRA.
The intolerance and killing in Ulster are anguishing. With the British-sponsored elected assembly stymied, political life there is at an impasse. Meanwhile, any prospects of talks between Britain and Ireland to try to work out some formula for gradual constitutional unification seem to be postponed until the governments in London and Dublin have stronger mandates for such talks.
In this stalemate something should be said for President Reagan's promise to encourage more investment in Northern Ireland in order to create jobs. Political problems sometimes begin to sort themselves out in a climate of economic buoyancy. But at the moment Ulster is at low ebb. It once had a standard of living twice that of the Republic of Ireland; today it is actually worse off - with 20 percent unemployment, failed factories, and slum-ridden cities. It is just possible that a more vigorous effort to inject new industry would improve the political atmosphere as well. Here is where Irish-Americans - Protestant and Catholic - might usefully direct their energies.
Mr. Reagan, who had an Irish Catholic father and a mother of English-Scottish Protestant descent, issued the challenge when he said, ''We cannot remain indifferent to the tragedy that confronts the people of Northern Ireland and which affects the Republic of Ireland, Britain, and their friends in the United States.'' It is to be hoped he follows through.