In the years since 1966, when both Jimmy Carter and Ronald Reagan first ran for governor, federal social welfare spending has grown like Jack's beanstalk. Fourteen years ago the government spent $46 billion on all such programs; this year it will spend nearly $300 billion.

Carter and Reagan hold sharply different views of this revolutionary change, views that give voters next month a real choice. In practice, though, it is difficult to predict that government social welfare programs will be dramatically affected no matter who wins the election.

Before this revolution even began, Reagan argued eloquently that the federal government was much too generous for the nation's good. He lent his rhetorical energy to the fight against Medicare, to cite one program that contributed substantially to the revolution on the grounds that it was a back door to "socialized medicine."

Federal aid to education, Reagan said repeatedly in the mid-1960s, was a ruse to create "a federal school system" based in Washington. The entire welfare state was a menace that would deprive the country of "individual freedom and our free economy," which Reagan called "our defense against communism."

Carter, on the other hand, has never complained that government has done too much to help needy Americans. He has always cast himself as a "moderate" within the Democratic Party, which means he has invoked a need for fiscal restraint to oppose some spending programs. But even the moderate wing of the Democratic Party was far more enthusiastic about federal social welfare programs than Ronald Reagan ever was. In a way, the revolution of the late '60s and '70s represented a victory of the dark forces of federalism that Ronald Reagan dedicated himself to defeat in the 1960s.

As in other areas of fundamental disagreement between the two candidates, the differences here are less stark today than they would have been years ago. Reagan has long since come to terms with federal social welfare programs and does not demand their dismantling. In his speeches, he no longer warns that socialized medicine is the inevitable consequence of Medicare.

In part Reagan's new attitude is a natural reflection of the true nature of these multibillion-dollar programs. Only a small fraction of them represent aid to really poor people; most are transfer payments like Social Security and Medicare or aid to education that benefit the great middle class, often predominantly so.

But even in the formal campaign literature of the Reagan-Bush campaign, the Republican candidate does call for returning major social welfare programs, including welfare for poor Americans and federal aid to education (a $15 billion program this year) to the states, where he maintains they would be better and more democratically administered in a way more consistent with this country's oldest traditions. The Reagan campaign has not explained just how this could be done -- especially how it could be financed -- but instead offers proposals like this one:

"Gov. Reagan's ultimate objective is to transfer federal educational programs, along with the tax sources to pay for them, back to the state and local level."

Reagan's campaign literature uses the same words to describe his position on welfare.

Carter, by contrast, has boasted of the substantial increases he has sought in federal social welfare programs. In a submission to the Democratic Platform Committee last summer, for example, he compared his latest fiscal 1981 budget proposals to spending levels in the last Republican budget, and listed these figures: aid to education up 73 percent, youth unemployment programs up 300 percent, Job Corps up 159 percent, public transit aid up 70 percent, food stamps up 99 percent.

So the two major candidates for president represent starkly different traditions on the federal government's proper role as a provider of help to the nation's poor.

There is no area of federal policy in which Congress can more effectively circumscribe a president's authority than this one. The recipients of federal social welfare spending and those who believe in the moral necessity of providing this aid together constitute one of the country's most powerful interest groups. Reagan has implicitly admitted as much this year by refusing to name specific government programs that he would abolish or cut back, and by embracing some that he once decried. The vague talk of "ultimate objectives" quoted above is as far as Reagan has been willing to go.

If, as now expected, Democrats retain their congressional majorities, Reagan would be unlikely to get approval for his proposed transfer of education aid and welfare back to the states, or for other radical changes in federal social welfare programs. But a President Reagan would have the power of the veto to contest with Congress, and he could at least theoretically begin the annual budget process with social welfare requests that would be much lower than the Carter administration now projects for the years ahead.

Federal social welfare programs involve more than money, of course, most obviously in the field of civil rights. Reagan used to speak out against attempts to "legislate" federal solutions to discrimination against minorities. However, he has also said the federal government "has a responsibility, at the point of bayonet if necessary, to defend the constitutional rights of even the least individual among us."

Carter has favored the use of federal power to try to further integrate American society. He has also endorsed what amount to quota systems to guarantee minority participation in many fields, including education and federal procurement contracts.

Reagan opposes affirmative action programs based on quotas.

Reagan's attitude toward federal welfare seems to go back to the Great Depression when his father became a federal factotum in Dixon, Ill., handing out federal relief benefits. In his 1965 autobiography, Where's The Rest of Me?, Reagan describes his father's efforts to find some real work -- albeit menial -- that the men in town who had lost their jobs could do so they wouldn't feel utterly dependent on New Deal relief programs.

Jack Reagan worked out a system of work-sharing that all the men liked, his son wrote, but soon the new federal welfare bureaucracy moved in on him, eventually denying men welfare if they had taken one of the part-time jobs Jack Reagan had found, or forcing them to apply all over again for welfare benefits every time they did a few days' work. The bureaucrats made Jack Reagan's life "one of almost permanent anger and frustration," Ronald Reagan wrote.

In public life Reagan has often spoken in strong language about welfare recipients.In the 1976 New Hampshire primary, for example, when Reagan campaigned on a proposal to return welfare programs to the states, he said that some poor people and minorities might have to move from states that refused to provide adequate benefits. "You can vote with your feet in this country," The New York Times quoted Reagan as saying. "If a state is mismanaged you can move elsewhere."

In the Florida primary in 1976, Reagan told a Fort Lauderdale rally that working people were outraged when they waited in checkout lines in supermarkets and saw a "strapping young buck" ahead of them buying T-bone steaks with food stamps.

As governor of California, Reagan sought to impose controls on some kinds of welfare programs, but did not attempt any wholesale dismantling of them. He initially made sharp cuts in state mental health programs, but eventually approved a bigger state program in the field than he had inherited. The Reagan administration in Sacramento did fight federal efforts to raise the level of California welfare benefits, and also tried to cut state Medicaid benefits, but was eventually forced to abandon both policies. In the end, welfare benefits increased by more than 40 percent during Reagan's eight years as governor.

The Reagan administration fought periodically with California programs sponsored by the Office of Economic Opportunity, particularly the California Rural Legal Assistance program, which it tried to have eliminated altogether. But the Nixon administration refused to go along.

During this campaign, Reagan has actually proposed expanding federal transfer payments and tax benefits for middle-class Americans, suggesting an end to earnings limits for recipients of Social Security and tuition tax credits for parents of private school students. Carter has not proposed any new benefits of this kind.