OK, I'm gonna do it...
Here is a post I used in an online class I was teaching two years ago, when we were discussing just war theory, and a student brought up Hiroshima and Nagasaki.
"In the 68 years since the one and only instance of atomic bomb usage (the two bombs dropped over Japan in August 1945), far fewer people in general have been killed in wars than were killed in the wars of the 20th century prior to August 1945, and it is precisely because of the atomic bomb—governments have been scared to death to start a nuclear holocaust because they know what the end result will be, and so wars have been tightly contained with far fewer casualties. Moreover, the deadliest bombings in WWII were not Hiroshima and Nagasaki, but Tokyo: on March 11, 1945, Tokyo was firebombed using conventional ordnance, and 100,000 people burned to death.
"Having said that, unlike most people taking this course, I have actually been to both Hiroshima and Nagasaki. I haven't been to Nagasaki in 44 years, but I was in Hiroshima last in 2006. When I was in Nagasaki in 1968, it had been 23 years since the atomic bomb blast there, and the city was as thriving as any city in Japan in the late 1960s, meaning it was a very thriving city. Hiroshima is very modern, a beautiful place to visit, complete with a modern major league baseball stadium and Shukkei-en, a wonderful garden.
"None of this is to say that a nation should desire to be bombed, either conventionally or with atomic weapons. Hiroshima and Nagasaki, however, are not so much a testament to the destructive power of human warfare as they are a testament to the creative power to survive and thrive in spite of the destructive power of human warfare. In WWII we saw the same spirit in London and Berlin; we have seen it in the last decades in the rebuilding of the former Saigon since the Vietnam war; and we are seeing it today in the capital of Iraq, as both the Saddamists and Islamofascists have been pushed out, and the people are setting about building a better Baghdad for their children.
"But let's get to the implication: the belief, held by more than a few, that America was clearly unethical in dropping the atomic bombs. For me to support the atomic bombing of Japan is what in legalese is called a statement against penal interests, because I have lived in Japan, have spent my life studying Japanese culture, and love the nation and the culture as much as anyone who is not Japanese.
"So why do I think the atomic bombing was the most ethical action that could have been taken at the time? Let's consider the situation in its own time. In WWII, we did not want to fight the Japanese, but the Japanese wanted to rule the Pacific, and were willing to fight and kill us, in spite of our willingness to negotiate, to obtain the fruits of their aggression. So the only way to convince the Japanese that they should cease their intimidation was to fight back, presenting superior force on the aggressor's terms, until the Japanese concluded that they could not win and no longer wanted to try—and that was when peace occurred, and that is the reason Japan is a peaceful nation and a trusted ally today.
"When the Japanese showed they were willing to kill and die by the thousands for a few lousy islands in Okinawa after we already had complete control of the air over Japan, they showed that a land invasion of Japan would result in deaths, not in the thousands, but in the millions, both Japanese and American (and Soviet, since they would have invaded Hokkaido while we invaded Kyushu). So we had a choice between an evil and a greater evil: we could atomic bomb and kill 150,000 Japanese in two industrial centers that had not yet been bombed and scare the iliatic residue out of the country, or we could continue to firebomb and kill hundreds of thousands of Japanese, then land on their shores and kill and die by the millions.
"It is easy to sit here 68 years later and talk about how horrid the atomic bombing of Hiroshima was, but it saved millions of lives, American, Japanese, and Soviet, and likely saved tens of millions of lives since as our wars have shrunk and become local, from Korea to Vietnam to Grenada to Afghanistan and Iraq, with the world scared by the atomic bomb.
"The irony of the issue is that to live in Hiroshima today is to live, as I said earlier in this message, in a beautiful, clean, affluent city, with the worst pro baseball team in the whole of Japan—yet you can stand where the bomb exploded and hear the cheers from a nearby stadium, watching the double-length busses going by. The world has been a much better place since I was born than it had been before, because of the atomic bombings of Hiroshima and Nagasaki. May they never have been necessary! But the Japanese flipped a switch at Pearl Harbor and Bataan and Singapore and Wake, and in war, once the switch has been flipped, there's no unflipping it.
"Starting a war, as the South did at Ft. Sumter, as Japan did at Pearl Harbor, as al-Qaeda did in Manhattan and Washington, never brings peace; but being victorious in a war that someone else has started on you always brings peace. If everyone in the world were to cease the use of intimidation to obtain what s/he wanted, then war would become unnecessary; until that day comes, the only way to end a war successfully is to be victorious, by the strongest means necessary."
Thanks. Very, very well-reasoned and -stated.
Of course Japan’s war started long before Pearl Harbor