Some years, they speak of “the final eradication in America of the age-old evil of poverty,” and then other years, the Democratic Party shifts its focus to “those who work hard, pay their bills, play by the rules . . .

In 1972, the party promises “a guaranteed job for all,” offering to “make the government the employer of last resort.” But 20 years later, the Democrats pivot and nearly apologize for themselves, appealing to “Americans who may have thought the Democratic Party had forgotten its way” by saying that it now “rejects the big government theory that says we can . . . tax and spend our way to prosperity.”

If Republicans from 1960 to today moved in fairly linear fashion to ever-more conservative stances on the economy, taxes and a slew of social issues, the Democratic evolution over the same period was a more jagged series of experiments with activist and statist approaches, interspersed with more traditional paeans to family, faith and individual initiative.

The Democrats’ 2012 platform, released this week at their convention in Charlotte, presents voters with a laundry list of positions designed to portray the governing party as the one committed to the middle class. The overarching idea is that “we’re all in it together,” and the document repeatedly says the party’s opponents are devoted to solving problems “from the top down,” focusing on the wealthy.

This year’s plank breaks little new ground, although for the first time, its support for legalizing same-sex marriage is definitive and clear, and it commits to combating anti-gay activity around the world.

But just as the GOP avoids the word “conservative” in its platforms, the Democrats never go near “liberal” or even “progressive.”

Since 1992, when the first Bill Clinton-era platform broke sharply with two decades of Democratic promises to use government to redistribute wealth, direct social change, and empower minorities and women, the party has sharply altered its rhetoric. Democrats have adopted words and phrases such as “opportunity,” “choice” and “smaller government” that their opponents began using during the Ronald Reagan years to win support from middle-class voters. The words “faith” and “God,” which appear only in passing or not at all in platforms from the 1960s through the ’80s, can be found 18 times in the 2004 document, as in “We honor the central place of faith in the lives of our people.”

Democratic platforms still spell out positions distinctly different from Republican stances on social and environmental issues, supporting abortion rights, affirmative action, and tighter regulations on polluters and financial institutions. Democrats consistently back a more expansive view of government’s role in science, the arts, and aid to the poor and the elderly.

But the party has struggled in recent decades to find the sweet spot between principle and political reality on issues such as guns, health care, the death penalty, school choice, nuclear power, relations with Cuba, and taxes.

In 1960, Democrats state plainly that they are open to “higher taxes [and] we will not allow political disadvantage to deter us from doing what is required.” Four years later, they call for tax cuts. Then, in 1968, they explain that in some years, reductions are necessary “to stimulate the economy” while at other times, the nation needs “tax increases to restrain inflation.”

Over time, the party settles on support for increasing the tax burden on the affluent, but its attitude toward government spending changes frequently. In 1980, the party promises not to skimp on spending: “For the sole and primary purpose of fiscal restraint alone, we will not support reductions in the funding of any program whose purpose is to serve the basic human needs of the most needy,” the platform says, touting increased spending for education, job training, and other services.

By 2004, Democrats promise to cut taxes for 98 percent of Americans, arguing that “the private sector, not government, is the engine of economic growth and job creation.”

The history of both parties over the past half-century is deeply entwined with the shifting politics of race. As their bases became more regionally, ideologically and demographically concentrated, the parties adjusted their positions to cobble together winning coalitions.

In the early 1960s, when conservative white Southerners still made up a big chunk of the party’s base, Democrats adopted many demands of the civil rights movement, but also took care not to alienate white supporters in the South.

“The time has come to assure equal access for all Americans to all areas of community life, including voting booths, schoolrooms, jobs, housing, and public facilities,” the 1960 platform says. But in 1964, the party adds a caution, opposing quotas “based on the same false distinctions we seek to erase,” and warning that prejudice cannot “be neutralized by the expedient of preferential practices” in hiring.

Eight years later, in 1972, Democrats endorse ratios and “proportional representation” to guarantee positions for women in federal jobs and for “poor people . . . at all levels of the Democratic Party.” That plank unreservedly embraces busing to accomplish school desegregation, an approach the next platform, in 1976, calls “a judicial tool of the last resort.”

On some issues, Democrats became markedly more liberal over time.

The party’s position on nuclear power, for example, moved in a straight line from strong support in the 1960s to queasy caution in 1976 (“Dependence on nuclear power should be kept to the minimum necessary”) to outright opposition through the 1980s. But this year’s platform endorses nuclear as part of an “all-of-the-above energy policy.”

Attitudes toward separation of church and state generally hardened over this period. In 1972, Democrats endorse federal aid to non-public schools, but in later years, the party’s definition of reform embraces public charter schools while rejecting vouchers for private and particularly parochial schools.

But on other issues, the party deliberately rejects its former identity as an overt advocate of liberal, activist government. In the two Clinton-era platforms especially, in 1992 and 1996, Democrats spurn the rhetoric of their recent past, adopting ideas and messages that had worked for the other party.

The 1992 platform announces a “Revolution of 1992 . . . a shift to a more efficient, flexible and results-oriented government that improves services, expands choices, and empowers citizens. . . . We believe in an activist government, but it must work in a different, more responsive way.”

These Democrats talk about “restoring the basic American values that built this country and will always make it great: personal responsibility, individual liberty, tolerance, faith, family and hard work.”

The second Clinton platform, in 1996, adopts language about fighting crime that earlier Democrats had rejected as nearly un-American. “Today’s Democratic Party believes the first responsibility of government is law and order,” the ’96 document says. In 1972, the party slammed the Nixon administration for using those same words, “ ‘law and order,’ as justification for repression and political persecution.”

The ’96 platform also boasts of establishing “the death penalty for nearly 60 violent crimes,” a sharp reversal from a promise in 1972 to “abolish capital punishment, recognized as an ineffective deterrent to crime, unequally applied and cruel and excessive.”

The Democratic evolution on capital punishment tracks with a shift on pro-gun-control rhetoric, from the 1968 platform’s promise to pass and enforce “effective . . . gun control legislation” and 1996’s praise of “courageous Democrats who defied the gun lobby” by banning assault weapons, to ever-stronger statements in 2004 and 2008 that vow to “protect Americans’ Second Amendment right to own firearms.”

The 2012 document proposes to “focus on effective enforcement of existing laws,” as well as seek to reinstate the ban on assault weapons.

The most radical statement of the party’s liberal vision appears in 1972, when the platform proposes to “guarantee a job for all,” greatly expand public employment, immediately withdraw all U.S. troops from Vietnam, abolish the Electoral College, break up corporate monopolies and “establish a system of universal National Health Insurance which covers all Americans . . . federally-financed and federally-administered.”

Democrats soon back off that concept, vaguely suggesting in 1992 “a uniquely American reform of the health-care system” and then settling in later years for just making care more affordable.

But in 2008, harking back to the party’s earlier, broader sense of government’s role, the idea of “guaranteed affordable, comprehensive health care” returns.

The first platform of the Barack Obama years proposes to cut poverty in half within a decade, using union organizing and transitional job programs. It declares climate change “a national security crisis” and includes the strongest statement on civil liberties since the ’70s.

“We reject illegal wiretapping of American citizens,” the platform says. “We reject the tracking of citizens who do nothing more than protest a misguided war. We reject torture. We reject sweeping claims of ‘inherent’ presidential power.”

The Democratic position on abortion doesn’t change much over the years — like the Republicans, Democrats first mention the issue in 1976 — but the party struggles over acknowledging discord within its ranks.

“We fully recognize the religious and ethical nature of the concerns which many Americans have on the subject of abortion,” the 1976 platform says before concluding that “it is undesirable to attempt to amend the U.S. Constitution” to overturn the Supreme Court decision upholding abortion rights.

By 1992, Democrats declare abortion rights “a fundamental constitutional liberty” and “stand behind the right of every woman to choose . . . regardless of ability to pay.” But in 2000, the party adds language recognizing “that members of our party have deeply held and sometimes differing views on issues of personal conscience like abortion and capital punishment.”

In 2008, that caveat is erased, leaving only an assertion that the party “strongly and unequivocally supports Roe v. Wade and a woman’s right to choose a safe and legal abortion.” This year’s platform repeats that support and adds an endorsement of family planning worldwide.