Graham wouldn’t dine alone or travel alone with a woman who wasn’t his wife. Graham believed in sin, and that no one was immune from it. He didn’t want to have an affair, so he didn’t give himself a chance to be alone with a woman.

He also didn’t want baseless accusations made about him. He knew that even if he wasn’t engaging in immorality, people still might spread rumors, because—you know—sin. His practice of never being alone with a woman who wasn’t his wife provided him the credible evidence he needed to avoid scandal.

Vice President Mike Pence’s decision to follow the Billy Graham rule increasingly seems like wisdom. He doesn’t spend time alone with women who aren’t his wife, and he doesn’t attend events where alcohol is served unless his wife, Karen, is with him. He’s got a track record of avoiding situations that could expose him to the risk of allegation.