The word “abortion” does not appear in a Republican Party platform until 1976, when the party concedes that it is deeply split between those who support “abortion on demand” and those who seek to protect the lives of the unborn.

The quest for lower taxes does not define Republicanism until the 1980s, and matters of faith play almost no role in the GOP’s plank until the 1990s.

The Republican Party, viewed through its quadrennial platform documents, is consistently business-oriented and committed to a strong defense but has morphed over the past half-century from a socially moderate, environmentally progressive and fiscally cautious perspective to a conservative party that is suspicious of government, allied against abortion and motivated by faith.

Influenced by the rise of tea party activists, this year’s platform, adopted Tuesday at the Republican National Convention in Tampa, has shifted to the right, particularly on fiscal issues. It calls for an audit of the Federal Reserve and a commission to study returning to the gold standard. There are odes of fidelity to the Constitution, but also a call for amendments that would balance the federal budget, require a two-thirds majority in Congress to raise taxes, and define marriage as a union between one man and one woman.

The new plank urges the transformation of Medicare from an entitlement to a system of personal accounts, increased use of coal for energy and a ban on federal funding to universities that give illegal immigrants in-state tuition rates.

House Speaker John A. Boehner (R-Ohio) expressed skepticism that the lengthy recitation of the party’s positions has much meaning or function.

“Anybody read the party platform? I never met anybody,” Boehner told reporters. He said the document should be no more than one page. “That way, Americans could actually read it.”

Party platforms are not easy to digest. They are the meat missing from a campaign menu dominated by sweet and sour TV commercials. Platforms are aspirational laundry lists, packed with sops to every interest group that makes up a modern party. But in retrospect, they provide a good guide to where the party is heading.

What it means to be a Republican has changed enormously over the past half-century. The GOP opposed a Palestinian state as late as 1992, went silent on the issue for eight years, then endorsed the idea in its past two planks. During the George H.W. Bush presidency, Republicans acknowledged global warming and boasted of efforts to commit billions of federal dollars to finding solutions. The party then spent two election cycles saying there was too much “scientific uncertainty” before finally accepting in 2008 that humans have a role in altering the climate.

The GOP, like its opposition, has responded to ideological, demographic and social change by hardening some of its positions and adopting entirely new planks, all part of an effort to create a coalition capable of winning national elections. In the Republicans’ case, that meant adapting and appealing to a new base in the South from the 1970s forward, becoming the dominant party of white suburbia, and finding ways to marry its traditional pro-business foundation with less affluent, more socially conservative voters.

Many positions Republicans often tout as traditionally conservative are actually relatively new to GOP ideology. Indeed, although the party’s stance on the issues has shifted rightward over the past 20 years, Republicans have studiously avoided using the word “conservative” in platforms.

For decades, the party presented itself as “moderate” or even “progressive.” The 1960 plank, for example, touts “progressive Republican policies” such as “liberal pay” and says the government “must be truly progressive as an employer.”

In 1972, the platform celebrates Republicans’ use of wage and price controls to curb inflation, a doubling of federal spending on manpower training, and a tripling of help to minorities.

Even the party’s most conservative platforms avoid that word, which first appears in 1992. From the 1960s to 2008, platforms liberally criticize “liberals,” but “conservative” is used almost exclusively to refer to judges.

From the 1960s through the ’80s, each plank reads like a snapshot of its time, capturing the frustrations of the party or the pride of those in power, sometimes wryly needling Democrats, other years slamming them hard. But from the 1990s forward, the platforms exhibit a sameness of rhetorical style, a reflection of the cut-and-paste reality of the computer age, in which entire sentences appear over and over in successive planks.

Even as ritual expressions of solidarity with the Philippines or calls to abolish inheritance taxes survive each round of platform construction, the party line has changed markedly on many issues.

For decades, Republicans emphasized federal funding for public transit. Then, in 1980, a turn: “Republicans reject the elitist notion that Americans must be forced out of their cars. Instead, we vigorously support the right of personal mobility and freedom as exemplified by the automobile.”

Throughout the 1960s and ’70s, the GOP platform included vigorous support for an equal-rights amendment to protect women. Then, in 1980, the party stalemates: “We acknowledge the legitimate efforts of those who support or oppose ratification.”

In the 1960s and ’70s, the party positioned itself as a strong advocate for D.C. voting rights, in the Senate as well as the House. Then, in 1980, all mention of voting rights vanishes; the subject has not appeared since.

The first appearance of the abortion issue represents a party very much split between business-oriented moderates and religious conservatives: Abortion “is undoubtedly a moral and personal issue” on which Republicans disagree, the 1976 plank says.

Four years later, the issue has been settled: The GOP seeks a constitutional amendment protecting “the right to life for unborn children.” By 1992, the platform includes a call to appoint judges who oppose abortion.

Words such as “faith” and “heritage” rarely appear until the 1980s. (In 2000, religion plays an even larger role in the platform as the party goes beyond supporting prayer in public schools by seeking to allow them to post the Ten Commandments.)

The 1960 plank calls for government workers to receive “salaries which are comparable to those offered by private employers.” In 1984, public-sector workers are redubbed “bureaucrats” and “Washington’s governing elite” and are blamed for “an epidemic of crime, a massive increase in dependency and the slumming of our cities.” Republicans pledge a major cut in government workers.

The watershed platform of 1980 introduces tax cuts and an increasingly critical attitude toward government. “The Republican Party declares war on government overregulation,” it says.

Antipathy toward high taxes strengthens, resulting in 1992 in an explanation of how lowering taxes on the wealthy would lead to job creation, adding a simple declaration: “We will oppose any attempt to increase taxes.”

The platforms of 1980 and 1992 are the party’s big pivots, both in positions and rhetoric. But the roots of today’s Republicanism become clear during the 1964 conservative uprising that led to Barry Goldwater’s presidential nomination.

In 1960, Republicans give “firm support” to “the union shop and other forms of union security” and say “Republican conscience and Republican policy require that the annual number of immigrants we accept be at least doubled.” Four years later, the GOP bashes Democrats for being “federal extremists” wedded to an ever more intrusive central government. (Calls to limit benefits for illegal immigrants and deny citizenship to U.S.- born children whose parents arrived here illegally enter the platform in 1996.)

The optimism of 1960 — brimming with hope about new nations, weapons and ideas — gives way four years later to worry about “moral decline and drift” born of “indifference to national ideals rounded in devoutly held religious faith.” Suddenly, faith is at the core of Republicanism: The 1960 plank says nothing about religion; four years later, “faith” is one of the most frequently used words, along with “heritage” and “freedom.”

In 1960, the platform calls for “vigorous support of court orders for school desegregation” and affirms the rights of civil rights protesters. The 1964 plank calls for “discouraging lawlessness and violence” and “opposing federally sponsored ‘inverse discrimination.’ ”

The shift in substance comes with a notable pivot in tone. From the 1960 platform: “We have no wish to exaggerate differences between ourselves and the Democratic Party.” Four years later: “Let the Democratic Party stand accused.”

On foreign policy, the Republicans remained mostly consistent, calling for increased defense spending to combat communism. But the 1964 plank foreshadows the skepticism about the United Nations that would become a GOP mainstay from the 1990s forward. In 1960, the party pledges to “support and strengthen the U.N.” Four years later, it warns that “Republicans will never surrender to any international group the responsibility of the United States for its sovereignty.”

If the fiery rhetoric of 1964 presaged the Reagan and tea party revolutions, the path was not smooth. The Richard M. Nixon years brought a return — in the platform, if not in the coarser approach revealed in the Nixon White House tapes — of a more moderate message.

The 1968 platform would strike many voters today as a Democratic agenda — addressing air and water pollution, crowded slums, and discrimination against minorities, all with “a new mix of private responsibility and public participation in the solution of social problems.”

The ’68 plank also proposes to expand Social Security by lowering the age for universal coverage from 72 to 65. Future platforms remain supportive of maintaining benefits until 2004, when the party endorses George W. Bush’s proposal to shift to personal retirement accounts.

But amid that progressive Republicanism, the roots of the culture wars to come poke through the soil. The ’72 platform opposes quotas to achieve racial balance in college admissions and hiring, and rails against liberal hegemony on campuses. (That theme remains through 2008, when the platform says that “leftist dogmatism dominates many institutions.”)

By 1992, “family values” become a major theme. The platform states that “the media, the entertainment industry, academia and the Democrat Party are waging a guerrilla war against American values.” (That abbreviated version of the other party’s name, without the “-ic” suffix, appears for the first time in 1976, an early sign of the sniping that has come to dominate interparty rhetoric.)

The ’92 plank, the first to mention same-sex relationships, rejects any recognition of gay marriage or allowing same-sex couples to adopt children or become foster parents. The stand against adoption and foster care does not reappear.

The passage about marriage grows longer and more strident every four years, culminating in the 2004 call, echoed in 2008, for the amendment defining marriage as the union of a man and a woman. From 1996 through 2008, Republicans repeat that “homosexuality is incompatible with military service.”

The GOP also evolved on campaign finance. In 1992, it calls for reforms that include the elimination of “political action committees supported by corporations, unions or trade associations.” By 2000, that position morphs into one championing “the right of every individual and all groups to express their opinions and advocate their issues” — a veiled reference to efforts to eliminate limits on campaign contributions.

And the party’s attitude on the balance between civil liberties and aggressive security measures shifted dramatically after the terrorist attacks of Sept. 11, 2001. The 1996 and 2000 platforms oppose President Bill Clinton’s decision to close Pennsylvania Avenue in front of the White House, promising to reopen the street. But later platforms embrace George W. Bush’s emphasis on vigorous expansion of the government role in homeland security.