Originally published July 19, 2011: Wait a minute. Hadn't he already promised the only person with a stake in the matter - his wife, Karen - that he would be faithful to her? That's what weddings are for. Yet the Family Leader, a Christian-conservative advocacy group in Iowa, was insisting that he vow "personal fidelity" to his spouse as part of a pledge it wanted Republican presidential candidates to sign.

The 14-point document, with dozens of fine-print footnotes aimed at plugging loopholes, was just one of the pledges that have proliferated along the campaign trail this year, as activists try to enforce fealty to conservative principles.

Former Pennsylvania Sen. Rick Santorum ended up scrawling his name on the Family Leader pledge anyway. He has long supported the policy goals it listed: stopping gay marriage, fighting prostitution, pornography, and sharia law, appointing only judges who take a strict view of the Constitution's meaning, and encouraging government policies conducive to "robust childbearing and reproduction."

Besides, Santorum needs the endorsement.

That pledge, signed first by Rep. Michele Bachmann (R., Minn.), became infamous for a preamble that suggested black children had better family lives under slavery than they do in today's era of broken families. The Family Leader apologized and withdrew it, and both Santorum and Bachmann said that the slavery language was not on the versions of the pledge they signed.

The other candidates declined to sign. Mitt Romney's campaign called the pledge "undignified and inappropriate." Tim Pawlenty said he would prefer to use his own language to express his support for marriage.

It was a rare backlash against the right-leaning groups that dominate the Republican primary, with some candidates and their strategists wary of detailed pledges that could alienate general-election voters or make it harder to govern.

In addition to the marriage-vow document, pledges ask candidates to oppose abortion rights, to run government in tune with the Lean Six Sigma business-management technique, or to commit to the "cut, cap and balance" legislation pushed by the tea party. That legislation, which the House will consider Tuesday, involves cutting federal spending, capping future spending, and passing a constitutional amendment to require annual balanced budgets.

And, of course, there is the original: Grover Norquist's Taxpayer Protection Pledge, which binds signatories to oppose any net increase of taxes. It's designed to eliminate "weasel words," Norquist, head of Americans for Tax Reform (Elimination?), has said.

Santorum, among others, says the pledges are a healthy antidote to cynicism about political leaders who promise one thing and do another in office. Signing a pledge offers "something as serious as the vote we are asking for - a solid commitment," he said in a USA Today op-ed column last week.

Nobody can deny that the Norquist pledge has helped the modern Republican Party enforce ideological discipline - and win elections. It also has handcuffed Republican congressional leaders in debt-limit negotiations with the administration. They could win unprecedented cuts in government spending, perhaps even changes to entitlement programs, but President Obama is demanding some give on tax revenue - mostly in the form of eliminating loopholes that benefit corporations and the rich. That runs afoul of Norquist's pledge, however, and is anathema to rank-and-file GOP lawmakers, particularly in the House.

So the downside of pledge politics is to turn leaders into robots, doing the will of whatever interest groups have programmed their software. They can't change their minds, adjust to new facts, react to emergencies.

As the historian Garry Wills recently pointed out, the idea of government by "instruction" was rampant in the 18th and 19th centuries in parliamentary elections in Britain. Constituents detailed lists of positions they wanted taken and candidates promised to obey, becoming tools of the popular will.

Political philosopher Edmund Burke, running for a seat in the House of Commons in 1774, agreed that his Bristol constituents' opinions should carry "great weight" with him.

"But his unbiased opinion, his mature judgment, his enlightened conscience, he ought not to sacrifice to you, to any man, or to any set of men living," Burke said. ". . . They are a trust from Providence, for the abuse of which he is deeply answerable. Your representative owes you, not his industry only, but his judgment; and he betrays, instead of serving you, if he sacrifices it to your opinion."

Burke, an intellectual hero to many conservatives, probably would not sign the Norquist pledge. If he were around today and running for Congress in, say, Indiana, he would not survive a Republican primary.

Contact politics writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com. Follow him on Twitter @tomfitzgerald. Read his blog at www.philly.com/BigTent.