President Obama’s recent visit to the Japanese city of Hiroshima is an opportunity to reflect on the moral ramifications of one of the most horrific acts of war in history. Indeed, the President himself—rather than issue a cheap apology for the event—called for just such an exercise in critical thinking.

At the time, the logic behind the use of the atom bomb on Hiroshima—and, in short order, also on Nagasaki—was a simple and compelling one. Many argued the alternative was a grueling trench warfare with suicide Japanese solders—a battle for every hill, every yard, every city and village that would extend the war and result in the loss of as many as a million more lives. That argument resonated with a war-weary America at the time: a Gallop poll showed 85 percent supported the decision to use the atom bomb against Japan.

But can the bombing be morally justified? Especially in a Catholic moral framework?

The short answer: I don’t see how it possibly can.

The answer, of course, lies in just war theory, defined and honed over centuries and articulated by some of the greatest minds of the Church, like St. Augustine and St. Thomas Aquinas.

But before we get to the theory, it helps to reckon with the reality of what happened at Hiroshima. We’ve all seen the pictures of that sickly mushroom cloud, the scenes of a city flattened, and survivors suffering severe burns. Those images only begin to hint at the extent of the destruction that was unleashed by the atom bomb.

On August 6, 1945, moments after 8:15 in the morning, the bomb detonated above the city center of Hiroshima. Temperatures instantly soared to 10,000 degrees Fahrenheit—as hot as the surface of the sun, melting concrete and vaporizing bodies, burning their shadows onto the structures that survived.

Within the first second, the bomb had produced a fireball 13 times the size of an NFL football field and sent a shock wave at two times the speed of sound roiling through the city, flattening brick buildings over a mile away. For about 10 to 15 seconds after the explosion, the fireball glowed several times brighter than the sun and could be seen six miles away. Some of those unfortunate enough to see such infernal brightness were permanently blinded. Within the first minute, the fireball was a mile high and the shock wave had been felt as far as 15 miles away.

The ensuing firestorm consumed anything that remained in a five square mile area, blowing with hurricane force winds and sucking in air from the surrounding area, causing some who had survived the initial blast to die of asphyxiation, in one of the lesser known effects of the bombing. The final horror was a black radioactive rain that fell two hours later.

An estimated 70,000 to 140,000 lives were snuffed out that day. Many died of gruesome burns or radiation poisoning in the days and years that followed. (One estimate puts the number at 60,000 by 1952).

Such details are important not only in of themselves but also for our query here. Many of the other bombings of World War II devastated cities of our enemies, but there’s a bit more of a gray area with some of these raids: the bombings could conceivably be justified because the cities were centers of manufacturing, or had large numbers of soldiers stationed there, or had some other military value. I’m not saying I agree with that logic, but it’s more understandable.

Hiroshima too, it’s worth noting, did have military value as a target:

Hiroshima was by no means just a civilian target. It was Japan’s western military capital and home of massive munitions factories and Japan’s second largest military school. There was a military headquarters in the middle of town; factories churned out large amounts of military hardware; and the Mitsubishi Heavy Industries shipyard was one of the major builders of giant warships. Hiroshima’s port on the Inland Sea was the staging area for military action in China, Korea and Southeast Asia. (Source here.)

Here’s the point: whatever value Hiroshima had as a military target, the above account of the atom bomb’s effects makes it clear that there was no question that civilians were also targeted. (Remember, U.S. officials had tested the atom bomb. It’s not like its destructive effects came as an unexpected shock to those in the know.)

One of the first principles of just war theory is that the cause of the war must be a just one (the Latin phrase is jus ad bellum). An important corollary to this is that war must also be fought justly (jus in bello). The Catholic Church, especially in the last century, has been unequivocal in declaring that this teaching means that civilians cannot be deliberately targeted. For example, the Catechism of the Catholic Church states that “Non-combatants, wounded soldiers, and prisoners must be respected and treated humanely.” It goes on to elaborate on this general principle with the example of genocide, then this:

2314 “Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation.” A danger of modern warfare is that it provides the opportunity to those who possess modern scientific weapons especially atomic, biological, or chemical weapons—to commit such crimes.

Catholic Answers has a concise summary of just war doctrine here. Notably, they give the bombings of Hiroshima and Nagasaki as examples of violations, citing the principles laid down in John Paul II’s encyclical Evangelium Vitae:

These were not attacks designed to destroy targets of military value while sparing civilian populations. They were deliberate attempts to put pressure on enemy governments by attacking non-combatants. As a result, they were grave violations of God's law, according to which, “the direct and voluntary killing of an innocent human being is always gravely immoral” (John Paul II, Evangelium Vitae 57; other examples are given as well, such as the bombing of Dresden).

If there’s a gray area in there, I’m not seeing it. It seems pretty cut and dried.

Moreover, the Church has roundly rejected the utilitarian logic undergirding the decision to use the atomic bomb. (For example, see Veritatis Splendor 74 and Evangelium Vitae 15.) Utilitarians would be comfortable talking about how the deliberate taking of some life is necessary to save many more—this is antithetical to the Church’s entire approach to moral theology, especially in the last half of the twentieth century.

Nonetheless, while we may recognize the flawed reasoning, the argument plays on our emotions. Was the moral alternative really to exhaust perhaps a million more lives in an invasion? It’s worth tugging at this thread for just a bit, to show that the more moral way is not necessarily always as ‘extreme’ as it may seem.

In the first place, those estimates of casualties vary widely. The million-dollar figure is from the History Channel. A CNN report puts it at 250,000.

Second, was an invasion really the only other alternative? The threat Japan posed to the world, had been contained at this point. The United States completely dominated the surrounding sea and airspace above Japan. Battleships bombarded the Japanese homeland from its coast while war planes picked off targets further inland at will. With that kind of blockade, it’s hard to imagine Japan getting very far with any attempt to strike back, let alone rebuild its empire.

Some high-ranking U.S. military officials at the time apparently shared this view. One was future U.S. President Dwight D. Eisenhower. In his memoirs he wrote,

“In 1945 ... , Secretary of War Stimson visited my headquarters in Germany, [and] informed me that our government was preparing to drop an atomic bomb on Japan. I was one of those who felt that there were a number of cogent reasons to question the wisdom of such an act....

During his recitation of the relevant facts, I had been conscious of a feeling of depression and so I voiced to him my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and second because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives. It was my belief that Japan was, at that very moment, seeking some way to surrender with a minimum loss of ‘face.’ The Secretary was deeply perturbed by my attitude, almost angrily refuting the reasons I gave for my quick conclusions” (source here).

A round-up of notable dissenters from the time is available here.

Some sixty years later, some may say it’s easy to sit in judgment. But that is exactly what history is all about. Absent such moral judgments, we deny history the right to teach us, rendering it as little more than collection of jumbled facts and incongruous truths.