So it is with the misunderstanding and misinformation surrounding Ronald Reagan’s 11th Commandment. At the New Hampshire Republican debate this week, we all heard some commentators completely mangling and bungling that line. Every four years, it seems, we have to go through the nonsense of clarifying Reagan’s 11th Commandment.

The 11th Commandment was created in 1966 by Gaylord Parkinson, the Golden State’s Republican Party chairman. After the bloodbath in the 1964 California primary between Arizona Sen. Barry Goldwater and New York Gov. Nelson Rockefeller, Parkinson was trying to put the party back together.

The commandment never meant that one Republican could not criticize the policies or philosophies of another Republican. It meant only that one could or should not engage in personal attacks on another Republican.

Reagan adopted it fully that same year. During the 1966 primary, Reagan’s moderate GOP opponents savaged him, calling him “temperamentally and emotionally upset” and suggesting that his switch from Democrat to Republican “might indicate instability.” Reagan did not attack them in the same manner.

When the California governor announced his intention in November 1975 to challenge then-President Gerald Ford in the 1976 GOP primaries, the 11th Commandment came up immediately. Reagan had a long history of party loyalty — though he had challenged the GOP’s favorite, George Christopher, the moderate Republican mayor of San Francisco, for governor in 1966.

The Ford White House, however, had been dumping all over Reagan, beginning in 1974 — leaking slurs and asides to the media. Eager for an intramural fight, the national media were only too willing to coax the two antagonists into a brawl.

Reagan was still willing to give Ford the benefit of the doubt in August 1974. But when he decided Ford kept taking the party and the country to the left, embracing the policies of former President Richard Nixon and his secretary of state, Henry Kissinger, the Gipper became more and more dismayed.

To say Reagan and Ford had little use for each other is an understatement. Nothing set off Reagan more than for someone to slur his intellect or his manhood. Ford did both — even making jokes that Reagan dyed his hair. (He did not. He used a little dab of Brylcreem and copious amounts of water.)

What finally propelled Reagan into the 1976 race, though, was Ford’s snubbing of Aleksandr Solzhenitsyn, at the urging of Kissinger, when the Nobel Prize-winning writer was expelled from the Soviet Union and came to the United States. After years of U.S. diplomats groveling before the Soviets, Reagan had had enough. He was disgusted that the president worried more about offending the Kremlin than speaking for the American people.

Reagan invoked the 11th Commandment about gingerly going after Ford even as he announced his candidacy at a news conference.

The White House was not amused. “When you live up to the original Ten Commandments,” a spokesman said, “there is no need to add new ones.”

After losing the first five primaries, Reagan made clear what the 11th Commandment meant. It was not about personality; it was only about difference in policy. In the North Carolina primary, he tore into Ford and Kissinger over the Panama Canal and government patronage. “When Gerald Ford arrives,” Reagan told the crowds, “the band doesn’t know whether to play ‘Hail to the Chief’ or ‘Santa Claus Is Coming to Town.’” His riff about the Panama Canal, “We built it! We paid for it! It is ours! And we’re going to keep it!” prompted audiences to go wild.

In 1980, Reagan leveled George H.W. Bush over issues high and low — including Bush’s underestimation of Soviet intentions while serving as head of the CIA. In fact, Reagan also had little use for Bush during the 1980 primaries. The California governor knew that Bush, like so many in the American establishment, had a low opinion of Reagan’s intelligence and brand of conservatism.

Reagan, in his memoirs, noted the “personal attacks” leveled against him during the 1966 race and how he had adopted Parkinson’s edict in response. But it did not mean he would not criticize fellow Republicans over ideology and philosophy. Indeed, most of Reagan’s political career was marked by challenging the reigning Republican orthodoxy.

It would be unhealthy and a mistake for the current crop of Republican presidential aspirants to ignore the real meaning of Reagan’s 11th Commandment. The party needs a healthy debate over its future and the centrality of the GOP’s philosophy — championing the state or the individual.

No individual can house competing philosophies for long without ending up in the loony bin. The same goes for political parties — including the bipolar GOP.

The party is going to have to decide what it stands for once and for all — the Big Government Republicanism of Bush, former Massachusetts Gov. Mitt Romney, et al., or the Federalism of Goldwater and Reagan. Both sides have strong arguments to make supporting their views.

Yet it is not only a debate worth having; it is a debate that is necessary for that party’s survival.

Craig Shirley, president of Shirley & Banister Public Affairs, is the author of two books on Reagan’s campaigns. He is currently writing “December 1941: The Month That Saved America and Changed the World” and “Citizen Newt,” a political biography of former House Speaker Newt Gingrich. This fall, he will teach a class at Reagan’s alma mater, Eureka College, on the Gipper’s political campaigns.