In the emotionally charged field of educational policy, Ronald Reagan has staked out a position that puts him squarely at odds with his two major opponents.

Only Reagan wants to help private and parochial schools, and to provide aid to families who send their children to them.

And only Reagan speaks and writes about ending the public school "monopoly," a theme that fits in with his broad philosophical belief that the private sector can do most jobs better than the government.

"Right now in public education we are very close to a monopoly," wrote Reagan in his 1976 book, "Call to Action." "Every year thousands of parochial and private schools close down because they can't compete against the public schools, which drain off more and more in taxes. Most of us are left with no choice but the public schools, good or bad."

Reagan supports a limited program of tax credits to families paying private school tuition -- assistance long sought by Catholics.

Catholic backing was a key factor in Congress' near approval of such aid in 1978. The fight for it in the Senate was led by Sen. Daniel Patrick Moynihan (D-N.Y.), who warned of "fearsome" pressure toward state monopoly over education. The measure passed the House but died in conference, under the cloud of a threatened veto by President Carter.

Reagan also supports experimentation with a controversial plan to issue vouchers entitling children to attend private or public schools of their choice.

Public shool forces, led by the National Education Association, charge the tuition aid and a voucher system could lead to the destruction of public education in the United States.

The positions that candidates for the presidency take on educational issues are mainly symbolic. The federal government has only a limited role in financing secondary and elementary education, and in guiding the decisions of the nation's 107,000 local public schools.

Nevertheless, the views of a presidential candidate on education tend to reflect his thinking on social issues generally.

And in this election campaign, with many of the distinctions between liberals and conservatives blurrier than they were a few years ago, some of Reagan's educational positions may appeal to more than conservatives.

Conservatives such as economist Milton Friedman support voucher plans that would have the effect of substituting a private school "market" for parents to replace public schools. But a voucher plan that would preserve the public schools is also supported by California liberals who are now pressing for a statewide referendum on the issue.

Tuition tax credits for private schools appeal not only to Catholics but also to some non-Catholic middle-class families who have become dissatisfied with local public schools. And the credits also are supported by various advocates of more freedom of educational choice for parents, including members of the Liberation Party.

A few years ago, the stand of Reagan and of the Republican Party platform against mandatory busing to achieve school desegregation would have been branded by liberals as racist. But in 1980, some black leaders, and black families are questioning the effectiveness of busing -- especially within school districts with overwhelmingly black student enrollments.

Reagan and the Republicans also have pledged to abolish the Department of Education, a creation of the Carter administration. The symbolism of this position reached beyond education to American voters concerned about the growth of government bureaucracy.

None of these issues is more embroiled in politics, or more laden with emotion than the proposal for tuition tax credits for private school enrollees. e

The leading Senate opponent of the credits, Sen. Earnest F. Hollings (D-S.C.), has warned that they would "turn our education on its head, benefit the few at the expense of the many, proliferate substandard segregated academies, add to the federal deficit, violate the First Admendment and destroy the diversity and genius of our public schools."

Given the numbers of children attending private and parochial schools, this threat seems to proponents to be vastly exaggerated.

An estimated one out of five precollege educational facilities in the United States is funded by private or church contributions. But only 4.5 million children attend these facilities, compared with about 41 million children attending the $95-billion-a-year public school system. About half of the non-public schools are Catholic.

Nevertheless, public school proponents fear that such programs as tuition tax credits would set a bad precedent and would add to the already extensive problems of these schools.

Public school supporters acknowledge that parental disaffection is dangerously high and has led to renewed interest in private schools.

Scott Thomson, executive director of the National Association of Secondary School Principals, told a House committee this year that there has been a "rather significant flight to private schools in the last five or six years," and added that newly founded private schools "are not just segregation academies located in urban areas or the South."

According to the U.S. Census Bureau's Survey of Income and Education, 82 percent of children attending private school come from families with income under $30,000 a year.

Thomson said that parental concern with public schools is "a broad, nationwide phenomenon based upon, among other factors, 15 years of federal policy."

Mary McCreath, who served on the San Jose, Calif., Unified School District Board for 15 years, warned in an article in the San Jose Mercury last October:

"The tax revolt and the demand for austerity in the schools has led many parents to find a more enriched and acceptable private school for their children . . . We are close to crossing the fail-safe point as America hurtles toward a new and very changed social order."