In admitting this, Mr. Weiner captured an important distinction that has been lost in our culture, which tends to over-pathologize problematic behavior. He didn’t blame his “disease.” He knows that there is a difference between having a compulsion and acting on it. But there is an idea bigger than just controlling one’s impulses. It’s what legal scholars and philosophers call “diachronous responsibility.”

Consider the drunken driver. Once he is tanked up on whisky and heading to his car to drive home, it is unrealistic to expect that he will instead amble to the closest Starbucks to sober up or call someone to drive him home. A cycle has been tripped and the odds are that he’ll drive home intoxicated. If he kills someone, it’s no excuse. That’s because he had ample opportunity to be responsible: When he was sober and walked into the bar. That was his first mistake, and a totally avoidable one.

According to Stephen Morse, a law professor at the University of Pennsylvania, a person can be responsible for the ultimate harm, even if that person is somehow not responsible at the moment of committing an act, as long as three conditions are met: He must a) be responsible at other times, b) know or should know that he is at risk of causing those harms in a non-responsible state, and c) fail to take reasonable steps to prevent the harm from arising.

Mr. Weiner is three for three on the diachronous-responsibility test.

First, he is responsible at other times. Clearly, Mr. Weiner knew enough not to sext in front of his wife. Second, he knew or should have known that he was at risk of causing those harms in a non-responsible state. Mr. Weiner is an intelligent man who had watched his life crumble years before the offense. And third, he failed to take reasonable steps to prevent the harm from arising.