Around the world and across history, we see people turn to suicide when embroiled in conflicts—when someone has wronged them, or they themselves stand accused of a wrong.

And when a person in this situation does take his own life, blame and punishment often fall on his or her perceived adversaries. Among the Iroquois, in traditional times, a self-killer's adversary was recognised as something akin to a murderer. The same was true among the Cheyenne, who banished the adversary from the community. The legal code of Qing China classified driving another to suicide as a criminal offence, so that if your enemy died by his own hand in the course of a quarrel you might be imprisoned, tortured, or executed.

These are not mere anthropological curiosities. On 14 August, a professor was found dead at his home in south London. Within a week, another professor in Belgium had been suspended from his job. The dead man was Jason Arday, a sociologist credibly accused of plagiarism and fraud. The suspended scholar was Nathan Cofnas, a philosopher who published the article that triggered Arday's drastic fall.