The sudden embrace of social conservatism by top Republican presidential candidates has been widely misunderstood. It's been portrayed, particularly in the media, as political pandering of the first order-and nothing more. True, there's a large element of pandering when a candidate switches positions on abortion, gay marriage, and other social issues with an eye to gaining votes. But for a Republican seeking his party's nomination, shifting to the right on social issues is hardly shocking. Rather, it's quite normal, it's absolutely necessary, and it's likely to work.

There's a bonus in all this for social conservatives. Switchers on social issues usually stay switched. Ronald Reagan and the elder George Bush did so after becoming pro-lifers. All those Democratic presidential candidates in the 1980s and 1990s who switched sides on abortion from pro-life to pro-choice have stayed put. Tony Perkins, the head of the Family Research Council, says you only get to flip once on social issues. If you switch back, "you're in no man's land," a politician without a political base.

The newly minted social conservative who's made the most drastic move is former Massachusetts governor Mitt Romney. He's flipped on abortion, gay rights, and embryonic stem cell research, as Jennifer Rubin detailed in these pages a few weeks back ("Mitt Romney's Conversion," Feb. 5). Senator John McCain of Arizona has changed his view on Roe v. Wade, the 1973 Supreme Court decision legalizing abortion, from supporting it to favoring its reversal. And Rudy Giuliani, the ex-mayor of New York, has sought to take the edge off his social liberalism, even suggesting he'd nominate Supreme Court justices who might overturn Roe v. Wade.

It was Democrats with presidential ambitions who transformed the switch on social issues-especially on abortion-into a normal political event. Over the two decades after the Roe v. Wade ruling, the two parties sorted themselves out on abortion, Republicans emerging as the pro-life party, Democrats the pro-choice party.

More recently, one party has become reliably conservative on the broad range of social issues (Republicans), the other mostly liberal on those issues (Democrats). This, in turn, has forced presidential candidates of both parties to align themselves accordingly. So a stampede of Democrats who sought their party's presidential nomination after 1980 abandoned their opposition to abortion. The list included Bill Clinton, Al Gore, Dick Gephardt, Joe Biden, Dennis Kucinich, Tom Harkin, and Jesse Jackson.

For all those Democrats, switching was necessary, since a pro-lifer has little or no chance of winning the Democratic nomination. It's the same for Republicans, only in their case it's a pro-choice candidate who has the extreme disadvantage. Were Democrats somehow to anoint a pro-lifer as their presidential candidate, that would surely prompt a pro-choice challenger to run as an independent or third party nominee. With Republicans, a pro-choice nominee would spark a pro-life candidacy.

For Democrats, switching is painless. They not only put themselves on the side of party activists and liberal interest groups, they get right with elite opinion and the media. For Republicans, it's anything but easy. When they switch and endorse social conservatism, elite opinion is appalled and the press plays up their supposed insincerity.