The South Carolina and American flags flying at half-staff behind the Confederate flag in front of the state capitol in Columbia, S.C. (Mladen Antonov/Agence France-Presse via Getty Images)

THE CONFEDERATE battle flag in Columbia, S.C., did not fly at half-staff in the wake of last week’s tragedy in Charleston because it could not: The flag is permanently affixed to its pole on a war memorial, just steps from the capitol. To be lowered at all, it must be removed entirely. That is what should happen.

The flag, whose presence on South Carolina capitol grounds has tripped up Republican hopefuls for years, was removed from its post atop the state house dome in 2000 as part of a political compromise that also stipulated its appearance on a nearby memorial. It can come down only with a two-thirds vote from the state legislature, a move Gov. Nikki Haley (R) endorsed Monday alongside the state’s senators, Lindsey O. Graham and Tim Scott, both Republicans.

Some other prominent Republicans, such as Mitt Romney and John McCain, have spoken forcefully in favor of removing the flag. Others, such as Jeb Bush and Marco Rubio, have come down on the right side of the issue but have said the choice is ultimately one for each state to make. Others still, such as Mike Huckabee, have punted, claiming that presidential candidates need not share their stance on the flag at all.

Mr. Huckabee gets it wrong. A candidate’s position on South Carolina’s flag speaks volumes. Flying a Confederate flag, especially on state grounds and in the face of a racially motivated tragedy, does more than recognize history: It glorifies the worst aspects of our country’s past. When flag defenders say it represents “heritage, not hate,” they’re only half right. Certainly not everyone who cherishes the flag is hateful. But the heritage it represents is that of secession, defense of slavery and opposition to civil rights. It’s a heritage that should be studied but not celebrated.

Civil War memorials to fallen Confederate soldiers dot old battlefields on both sides of the Mason-Dixon Line, and statues of rebel soldiers stand tall on city streets as nearby as Alexandria. But monuments that were erected long ago now do little more than acknowledge that past. As historical artifacts, they lack the political potency of the Confederate battle flag. Unlike memorials and statues, flags can become rallying cries for people — in this case, people like suspected shooter Dylann Roof — who believe in what they stand for. The Confederate flag came back to Columbia in 1961 as a thinly veiled protest against the burgeoning civil rights movement. The message it sends is clear — and directly in contrast to the lessons of tolerance and forgiveness that the people of Charleston have been teaching the nation since last week’s atrocity.

South Carolina’s Confederate battle flag is the last on any state government grounds. With its removal, the nation would finally be saying that the flag is not a symbol worthy of respect. There is no excuse for any member of the South Carolina legislature to vote, or for any presidential candidate to say, otherwise.