In July 2002, an Israeli jet took out Salah Shehade, the commander of Hamas’s military wing, who had been involved in attacks responsible for the deaths of 474 people. While an assistant of his was also killed in the strike, so were 13 civilians including Shehade’s wife and daughter. International condemnation was swift and strong.

A few months later, Israeli intelligence learned that Hamas’s top brass were due to meet. But mindful of the reaction to the earlier assassination, Israeli leaders chose not to use a bomb to demolish the building; instead, a smaller missile was used and the leaders of Hamas escaped.

For Shlomo M Brody, author of the recently published Ethics of Our Fighters, the decision not to deploy heavier weapons was “a moral error that cost Israel dearly”. To avoid repetition of such a mistake, “Israel and other Western countries need to learn anew why inevitable collateral damage is justified in warfare”.

Although the book was written before October 7, it is not difficult to deduce what his position would be on Israel’s current campaign in Gaza.

While humanitarian demands were previously weighed against military necessity, many philosophers, he contends, have tipped the balance in favour of the former as a result of the 1977 protocol added to the Geneva Conventions, which covers protection of civilians. Neither Israel nor the USA has ratified the protocol.

He points out that civilian facilities such as hospitals that are used for military purposes lose their immunity and when guerrilla groups use non-combatants as human shields, “they bear responsibility for making them targets”. Armies owe a higher duty of care to their soldiers than enemy non-combatants in that they should not be expected to incur undue risk in order to avoid civilian casualties.

He is critical of what he regards as common misuse of the concept of “proportionality” when applied to military operations, arguing that “extensive” casualties do not necessarily amount to “excessive”. Instead, “thoughtful questions about proportionality and responsibility get overshadowed by knee-jerk reactions.”

Simply reacting to distressing images on TV screens is no way to arrive at an ethical judgment. “Media spectacles are not moral barometers,” he says. The medium “lends itself to replacing hardheaded analysis with sheer emotion”.

Rabbi Brody is a Harvard-educated scholar with a doctorate in law from Bar-Ilan University, who has taught at yeshivah and other Jewish institutes. He currently heads Ematai, an organisation offering a Jewish approach to health issues such as end-of- life treatment and organ donation.

Ethics of Our Fighters is aimed at general readers rather than legal academics or halachic specialists. Writing with clarity and cogency, he covers a lot of ground, drawing on both Jewish and secular codes and analysing episodes from the rape of Dinah in the Bible to the bombing of Dresden in World War Two to examine the ethical issues.

Underlying the book is the question how much Judaism has to say about such a fraught area. One Israeli rabbi, Shai Yisraeli (1909-1995), controversially suggested that there was no unique Jewish teaching and international conventions set the standards for soldiers to follow.

Brody looks at the classical rabbinic distinction between a milchemet mitzvah, an obligatory war, and a milchemet reshut, discretionary war. In antiquity, a king would be permitted to launch the latter to expand his territory — but the rabbis hedged it with conditions by insisting on the need first to consult the court of the Sanhedrin. The — for us, difficult — commandment to wipe out the Amalekites, which we read about in synagogue only last week, was effectively rendered inoperable in practice by the sages.

The bloody revenge of Jacob’s sons Shimon and Levi on the men of Shechem after the rape of their sister Dinah was cited by one rabbi to justify reprisals on Arab civilians by the Irgun after the death of Jews in terrorist attacks in the 1930s, but other rabbis pointedly noted Jacob’s deathbed condemnation of the violence of his sons.

The same biblical incident is wielded as a precedent in the notorious tract Torat Hamelech, Law of the King, penned by more militant rabbis. Brody comments that this “disgracefully allows for indiscriminate killing of an enemy population”.

He discusses the requirement stipulated by Maimonides to keep the “fourth side open”, that is for an army to ensure there is a route for people to flee a city under siege. In 1982, when the Israeli army had surrounded Beirut where the PLO had set up headquarters, Chief Rabbi Shlomo Goren ruled that this provision should be respected.

Brody contrasts the outlook of the influential Rabbi Tzvi Yehudah Kook, the inspiration behind the religious settler movement, who believed the conquest of the Holy Land required a mandatory war, with that of Rabbi Yehuda Amital, the doveish founder of a religious party advocating land for peace. Another rabbinic figure,who appears early in the book, is Rabbi Aaron Samuel Tamares from Poland who, repelled by the bloodletting of the First World War, was unusual in espousing a philosophy of pacifism.

What Brody himself offers is what he calls a Jewish Multivalue Framework for Military Ethics, a nine-point guide to discussing the topic. These values vary from the belief in the dignity of all human beings — who are created in the divine image — to the understanding that it can be just to resort to arms. In any given circumstance, some values may take precedence over others, but it depends on a case-by-case basis.

As he writes, “The moral life is too complex to be resolved by one overriding principle. The complexity of the dilemmas forces us to consider a variety of legitimate moral factors…”

Whether or not you agree with all his opinions, Brody has produced an informative sourcebook that can help frame debate around a subject in which it is all too easy to rush to judgment.

Ethics of Our Fighters: A Jewish View of War and Morality, Shlomo M. Brody, is available from Maggid, £25.73