In 1999, the world watched in shock and dismay as President Bill Clinton underwent an impeachment trial for lying under oath about his extramarital affair with White House intern Monica Lewinsky. Although Clinton was ultimately acquitted of charges of high crimes and misdemeanors, he did admit to the relationship and his attempts to cover it up.

Many critics point to Clinton’s actions as indicative of a severe lack of ethics in America. They insist that modern Americans are far less ethical than previous generations and more willing to accept unethical behavior in their leaders. According to other commentators, however, the notion that Americans were more ethical in years past is simply a myth. For example, they argue, among former presidents, Franklin D. Roosevelt continued to have an affair after promising his wife he would end the relationship, and recent scientific evidence has strongly indicated that Thomas Jefferson...