Was the dropping of a nuclear bomb on Hiroshima an act of evil or an act of morality?
There is no denying the horror of the death dealt out to the innocents of the city on that day but no denying either that this was an act which helped terminate a brutal war.
If Little Boy had not detonated above Hiroshima on that fateful day in August of 1945 then the war almost certainly would have ground on... And hundreds of thousands on both sides could have died. The Japanese soldiers and civilians were sworn to die for their Emperor... any campaign in Japan would have been a terrible one.
Throughout years of reporting, including spells in the Middle East during both Gulf wars, I have always been fascinated by the idea that wars should have rules. Why is okay to shoot someone but not to gas them? Okay to drop a bomb but not plant a mine?
And the bombing of Hiroshima and Nagasaki encapsulates that moral dilemma. For the physicist Ben Bedersen involved in the Manhattan Project, to whom I spoke in the build up to my special 5 live Daily programme, the morality is clear. The bomb saved American and indeed Japanese lives, and it stopped once and for all the brutality of the Japanese forces.
But read the accounts of those who survived the hell on earth created by that bomb and ask yourself, how can the use of a nuclear weapon be justified?
I have covered a good number of these remembrance ceremonies for BBC Radio 5 live in recent years, most memorably perhaps those in Normandy which marked D Day and the beginning of the end for the German forces.
In most of those ceremonies there is a simple enough message... us versus them... good versus bad... bravery in the face of great danger... an unflinching commitment to doing one's duty. I will remember forever one of the veterans on the beach below a fluttering standard as the last post sounded, fighting back the pain to drag his body upright and salute those who had fallen. Those Normandy veterans are true heroes, the kind of heroes who pretend there was nothing remarkable in their bravery, they were simply doing their bit, and quite rightly the nation paid tribute.
But how will the world mark Hiroshima? With sadness perhaps, with pride perhaps, with sorrow, with despair? How will the people of Japan remember the event and how will the thousands who visit Japan pay their respects?
The nuclear age is of course full of those contradictions. Why is it right for us to have nuclear weapons and wrong for anyone else to do so? How can we rely for our protection on a weapon which few of us would actually be prepared to use? How can we blithely speak of mutually assured destruction? Except that, many argue, it works.
Even though many of my friends in Britain and I grew up expecting there to be a nuclear war, it did not happen. Hiroshima began seventy years of relative peace for us, even if much of the world is in turmoil. Which brings us back to that central question with which I began. Was this act of supreme violence the right thing to do?
So a good deal to remember and a good deal to discuss as the world focuses upon Hiroshima this week.
On 5 live we'll speak to survivors and witnesses of the bomb, now in their 70's and 80's, whose testimony will, I suspect, provide a chilling reminder of the horror unleashed upon Hiroshima, as well as to those who still believe that they were right to drop the bomb.
We'll try to reflect the pain of those involved and we will talk about the future also. Would our country be safer without nuclear weapons? Can we afford such weapons and their delivery systems? Can or should we disarm unilaterally? Is it possible to put the genie back in its bottle?
I also hope the programme serves as a reminder of how lucky many of our generation have been, and of the potential consequences of failure as our governments struggle to maintain that peace.
Peter Allen presents Hiroshima 70 Years On on BBC Radio 5 live on 6 August at 10amSuggest a correction