“I have blood on my hands.” This is what Robert Oppenheimer, the mastermind behind the Manhattan Project, told US President Harry Truman after the bombs he created were dropped on Hiroshima and Nagasaki killing over an estimated 226,000 people.

The President reassured him, but in private was incensed by the ‘cry-baby scientist’ for his guilty conscience and told Dean Acheson, his Secretary of State, “I don’t want to see that son of a bitch in this office ever again.”  

With the anniversary of the bombings this week while Christopher Nolan’s Oppenheimer is in cinemas, it is a good moment to reflect on the two people most responsible for the creation and use of nuclear weapons: one wracked with guilt, the other with a clean conscience. 

Who is right? 

In his speech announcing the destruction of Hiroshima and Nagasaki, Truman provided the base from which apologists sought to defend the use of nuclear weapons: it “shortened the agony of war.”  

It is a theme developed by American academic Paul Fussell in his essay Thank God for the Atom Bomb. Fussell, a veteran of the European Theatre, defended the use of nuclear weapons because it spared the bloodshed and trauma of a conventional invasion of the Japanese home islands.  

Military planners believed that this could have resulted in over a million causalities and hundreds of thousands of deaths of service personnel, to say nothing of the effect on Japanese civilians. In the lead up to the invasion the Americans minted half a million Purple Hearts, medals for those wounded in battle; this supply has lasted through every conflict since. We can see here the simple but compelling consequentialist reasoning: war is hell and anything that brings it to an end is worthwhile. Nuclear weapons, while terrible, saved lives.  

The problem is that this argument rests on a false dichotomy. The Japanese government knew they had lost the war; weeks before the bombings the Emperor instructed his ministers to seek an end to the war via the good offices of the Soviet Union or another neutral state. There was a path to a negotiated peace. The Allies, however, wanted unconditional surrender.  

We might ask whether this was a just war aim, but even if it was, there were alternatives: less indiscriminate aerial attacks and a naval blockade of war materials into Japan would have eventually compelled surrender. The point here isn’t to play at ‘armchair general’, but rather to recognise that the path to victory was never binary.  

However, this reply is inadequate, because it doesn’t address the general question about the use of nuclear weapons, only the specific instance of their use in 1945. There is a bigger question: is it ever ethical to use nuclear weapons. The answer must be no.  


Because, to paraphrase American philosopher Robert Nozick, people have rights and there are certain things that cannot be done to them without violating those rights. One such right must be against being murdered, because that is what the wrongful killing of a person is. It is murder. If we have these rights, then we must also be able to protect them and just as individuals can defend themselves so too can states as the guarantor of their citizen’s rights. This is a standard categorical check against the consequentialist reasoning of the military planners.  

The horror of war is that it creates circumstances where ordinary ethical rules are suspended, where killing is not wrongful.

A soldier fighting in a war of self-defence may kill an enemy soldier to protect themselves and their country. However, this does not mean that all things are permitted. The targeting of non-combatants such as wounded soldiers, civilians, and especially children is not permitted, because they pose no threat.   

We can draw an analogy with self-defence: if someone is trying to kill you and you kill them while defending yourself you have not done anything wrong, but if you deliberately killed a bystander to stop your attacker you have done something wrong because the bystander cannot be held responsible for the actions of your assailant.   

It is a terrible reality that non-combatants die in war and sometimes it is excusable, but only when their deaths were not intended and all reasonable measures were taken to prevent them. Philosopher Michael Walzer calls this ‘double intention’; one must intend not to harm non-combatants as the primary element of your act and if it is likely that non-combatants will be collaterally harmed you must take due care to minimise the risks (even if it puts your soldiers at risk).  

Hiroshima does not pass the double intention test. It is true that Hiroshima was a military target and therefore legitimate, but due care was not taken to ensure that civilians were not exposed to unnecessary harm. Nuclear weapons are simply too indiscriminate and their effects too terrible. There is almost no scenario for their use that does not include the foreseeable and avoidable deaths of non-combatants. They are designed to wipe out population centres, to kill non-combatants. At Hiroshima, for every soldier killed there were ten civilian deaths. Nuclear weapons have only become more powerful since then.  

Returning to Oppenheimer and Truman, it is impossible not to feel that the former was in the right. Oppenheimer’s subsequent opposition to the development of more powerful nuclear weapons and support of non-proliferation, even at the cost of being targeted in the Red Scare, was a principled attempt to make amends for his contribution to the Manhattan Project.  

The consequentialist argument that the use of nuclear weapons was justified because in shortening the war it saved lives and minimised human suffering can be very appealing, but it does not stand up to scrutiny. It rests on an oversimplified analysis of the options available to allied powers in August 1945; and, more importantly, it is an intrinsic part of the nature of nuclear weapons that their use deliberately and avoidably harms non-combatants. 

If you are still unconvinced, imagine if the roles were reversed in 1945: one could easily say that Sydney or San Francisco were legitimate targets just like Hiroshima and Nagasaki. If the Japanese dropped an atomic bomb on Sydney Harbour on the grounds that it would have compelled Australia to surrender thereby ending the “agony of war”, would we view this as ethically justifiable or an atrocity to tally alongside the Rape of Nanking, the death camps of the Burma railroad, or the terrible human experiments conducted by Unit 731? It must be the latter, because otherwise no act, however terrible, can be prohibited and war truly becomes hell.