Republican calls for military superiority over the Soviet Union are impossible to fulfill and will only lead to a perilous escalation in the arms race, Secretary of State Edmund S. Muskie warned yesterday.

Muskie's critcism was in tune with a sudden chorus of Carter Administration voices that sang out alarms yesterday on the dangers of presidential challenger Ronald Reagan's defense policies while they defended their own. They also assaulted several of Reagan's domestic proposals as "preposterous."

Without naming the Republican nominee, Muskie told an audience at Nortre Dame University that under Reagan-style interventionist policies, the United States could be "endlessly at war all over the globe." And he asked, "How would we then differ from the Soviet Union and its actions in Afghanistan and Ethiopia?"

Reagan's insistence on superiority "may sound grand in speeches," he said, "but the Soviets will no more allow us to gain such a position than we will allow it to them. A search for superiority would simply create a massive, dangerous new arms race."

At the same time, Muskie contended that U.S. and allied forces are a match for any adversary and that "any notion that we are neglecting our defense posture is absurd."

The Republican platform, with Reagan's endorsement, calls for U.S. superiority over the Soviet Union, rather than parity. Reagan also charged that Carter allowed this country's military strength to wither.

Campaigning in Des Moines, Iowa, Vice President Mondale said that Reagan's suggestion that the United States scrap the SALT II agreement with Russia and negotiate a more favorable pact was "unwise, imprudent and dangerous." Asked about Muskie's speech, Mondale said the secretary of state was "talking about an attitude . . . that there is an American military solution for all the internal problems in the world." He said the error of that view was "a lesson we learned at terrible cost in Vietnam."

Mondale said that Reagan had once suggested U.S. military intervention in Rhodesia. If the United States had done taht, instead of following the diplomatic course, he said, "it would have been a tragedy."

On another front, Secretary of Defense Harold Brown said yesterday that failure to ratify SALT II could propel the United States and the Soviet Union into an arms race that would cost this country between $30 billion and $100 billion during the 1980s.

"We wouldn't be any better off militarily . . . and probably a good deal of it would come out of our conventional forces," Brown said in an interview aired on the Cable News Network, as he reaffirmed the administation's intention to press for ratification of the controversial strategic arms limitation treaty.

Reagan has criticized SALT II, saying it would have to be renegotiated in order to meet his approval.

At the White House, meanwhile, press secretary Jody Powell and domestic affairs adviser Stuart Eizenstat held a briefing where they blasted three Reagan proposals made this week: phasing out the inheritance tax, ending the Social Security earnings limit and providing tuition tax credits to parents of children in private schools.

These proposals would cost taxpayers up to $18 billion, with increased military and other programs that would total $41 billion in new spending.

Terming the package "an economic mishmash that is clearly inflationary," Powell said, "American voters have a right to know that Gov. Reagan is saying one thing to one audience and something entirely different to another group."