There is a reason Petraeus generally received good press, even from those skeptical of American military involvement in Iraq and Afghanistan. During briefings and discussions, he was supremely informed and often breathtakingly candid — an attribute that involves risks but establishes credibility. He possesses a comprehensive knowledge of leaders and events in the Middle East and Central Asia. His career had not only been successful; it demonstrated that America is capable of complex international responsibilities. Petraeus is a generator of national confidence.

So why, exactly, should marital infidelity be disqualifying? This is not an easy or simple determination in any field of public leadership and responsibility. With human beings, it is necessary to leave room for complication. A person who cheats on his or her spouse can show courage on the battlefield or loyalty to his or her country. Faithlessness in one area does not extend to every area. Most people have hidden flaws and failures of various kinds, which may or may not have broader relevance to their work. …

By all accounts, Petraeus’s personal failure did not involve the abuse of power, criminal acts or security breaches. But his case also demonstrates how messy infidelity can quickly become — messy enough to involve harassing e-mails and to attract the attention of the FBI. People at their most ardent are also at their least rational. And this is most damaging in fields, such as intelligence, where the essence of leadership is judgment.