On the morning of Oct. 24, two Republican leaders were offering the country starkly dissimilar definitions of America's role in the world. Ronald Reagan was in New York addressing the U.N. General Assembly and Sen. Mark Hatfield of Oregon was in Washington delivering a speech on the Senate floor. They not only marched to different drummers; the drumsticks didn't match, either.

Two Americas were on view. The president offered himself to the United Nations as a world statesman. Familiar words of our innate goodness and dedication to peace were sounded, though in truth the leaders of other countries had come to the General Assembly earlier in the week preening with their goodness and dedication. Where Reagan's Americanism went beyond the customary promo that he excels in giving was in the line that he "would welcome enthusiastically a true competition of ideas" with the world community, especially the Soviet Union.

In Washington, Hatfield, in language that was as blunt as Reagan's was surreal, argued that when it comes to the competition of ideas the Reagan administration is chicken. He had in mind -- embedded in his mind, in fact -- the recent withdrawal of the United States from the compulsory jurisdiction of the World Court. In early October, the administration ended 39 years of acceptance of the rulings of the International Court of Justice, which is based in the Netherlands.

The walkout was in reaction to the suit brought to the court by the Nicaraguan government, which believes that the Reagan administration's mining harbors in Nicaragua and funding the contras broke international law. The 16 judges of the court, including one from the United States, saw the charges as well founded and agreed to hear the case. In January, the administration said that although it would not involve itself in the Nicaraguan case it would still support the court itself. As the months passed, that line was seen as not sufficiently hard. Total withdrawal, not partial, was called for.

On the Senate floor, Hatfield spoke of "a dangerous ideological agenda" at work. It was one that "holds that nothing should stand between the United States and the pursuit of its goals by whatever means it deems necessary." Pulling out of the court is "a step back into the jungle rather than a step forward into enlightenment."

Since it is in the Nicaraguan jungles where the Reagan-supported contras are defending freedom by destroying villages and burning hospitals, much of the opposition to Hatfield's speech was based on loyalty to the president in his mission to overthrow the Sandinistas. Hatfield wasn't talking about that. His comments had come in support of an amendment he offered to an appropriations bill. It would have denied funding to such international groups as the World Health Organization and the Food and Agriculture Organization as long as the United States is not subject to the World Court. The amendment, a long shot at best, or what is called in the Senate "a symbolic act," was defeated 74-21.

That won't end the matter. In the Senate floor debate, the argument raised by Sen. Charles McC. Mathias (R-Md.) went unanswered: How can the United States, "which rightly prides itself on being the most vital democratic nation on earth," turn "its back on the leading international body dedicated to advancement of the rule of law?"

The behavior of the Reagan administration is the kind that projects the United States as a sore loser before it loses. Where is the "true competition of ideas" that Reagan tried to sell at the United Nations? The policy that led to the attacks on Nicaragua was wrongheaded. Now the decision to snub the court reveals the United States as bullheaded.

The World Court has its weaknesses. Its wisdom falls short of King Solomon's and, with only 44 of 159 U.N. countries as members, it should be called the Semi-International Court of Justice. Despite that, it functions; it has been supported by every president and every Congress since 1946; and as Sen. John Chafee (R-R.I.) noted, the court has never decided against the United States.

Was the prospect of the first defeat coming on the Reagan watch too much for the president's advisers. Elliott Abrams, who is part of the meat-ax wing of the conservatives who counsel Reagan, said in September that "Nicaragua is in the middle of a propaganda blast, and it has chosen the World Court as its forum. They are putting out an awful lot of lies."

If they are liars, what's the worry? Let Abrams go to the court and prove it. The trouble is, it isn't a lie that the harbors were mined or that the United States is paying one group of Nicaraguans to kill another group of Nicaraguans. Does international law sanction that?