Those who know Benjamin Netanyahu, the Israeli prime minister, say he likes to test his opinions against robust argument, often at length. This column is an account of one such — imagined — conversation.

Netanyahu tends to see issues through the prism of the Holocaust, and the deep well of anti-Semitism it plumbed. On the part of the Nazis, of course, but also elsewhere in Europe — in Poland, Ukraine, the Baltic States, Hungary, Romania and France. After the war was over and the facts of the Holocaust became known, returning Jews were attacked and killed in the Polish countryside, and Stalin embarked on a murderous anti-Semitic program which — had it not been for his death in 1953 — seemed set to result in at least some major pogroms, if not another mass killing on the scale of the Nazis’. This realization, for anyone Decent, is at least sobering. For a Jew, it raises the specter of an eternal horror that can rarely be wholly dismissed.

Just as Anthony Eden, the British prime minister, viewed Egyptian President Gamal Abdel Nasser as an Arab Hitler when Nasser nationalized the Suez Canal in 1956, so Netanyahu tends to see Mahmoud Ahmadinejad as the same reincarnation. That means that the Iranian president is, in the Israeli’s mind, not just a fanatical anti-Semite, but one who will pursue his fanaticism at all costs – including causing great damage to his own people.

Fanaticism trumps rationality. Rational people wish to stay alive; fanatics commit suicidal murder for a cause. Rational leaders weigh the costs and benefits of aggression; fanatical leaders pursue their aims to the point of killing their state. Netanyahu believes that Ahmadinejad is the latter sort of leader. And thus he is inclined to think that Israel has no choice but to launch a pre-emptive strike while Iranian nuclear facilities are still vulnerable and before Iran moves them deep underground to complete the final stages of producing nuclear weapons.

However, he knows that the Israeli political and military establishment, and society, is deeply torn on the issue. There is, as yet, no decision, no one line. The complexities of making such a decision are formidable, even by Middle Eastern standards. Thus, as one who likes to test his views, earlier this week he invited a distinguished political scientist, well versed in the threats and opportunities of Israeli security but known to be opposed to a pre-emptive strike, to argue with him one evening in his office.