Michael Walzer published “Just and Unjust Wars,” an attempt to delineate the rights and wrongs of warfare in both its causes and its conduct, in 1977. In the nearly 50 years since, no other book on the subject has matched its influence. The precepts are not complicated: it is just to defend your country from an invasion and it is unjust to invade a country that has not attacked you—although Walzer does allow for exceptions, mostly for humanitarian causes. It is just to assume certain risks to avoid civilian casualties and it is unjust to bomb towns indiscriminately to compel an enemy to surrender. The justice of going to war—what philosophers call jus ad bellum—is separate from jus in bello, the justice of how a war is fought. The war in Gaza has made Walzer rethink one of the book’s fundamental principles. “The wall between jus ad bellum and jus in bello, which had sustained his theory for almost half a century, was no longer sturdy,” Jordi Graupera writes. As Walzer said to him, “There is a sense in which the carnage of Gaza, the ongoing carnage, simply made the war unjust.” Read about why a philosopher of war is now reconsidering his seminal work: newyorkermag.visitlink.me/T7…