
I think that everybody—pro and con—should read 140 Days to Hiroshima: The Story of Japan's Last Chance to Avert Armageddon by David Dean Barrett who uses Japanese sources (including Cabinet minutes) to look at Japan's decision making process before, during, and after the bombs were dropped.
* https://www.goodreads.com/book/show/51089656-140-days-to-hir...
* https://www.nationalww2museum.org/about-us/notes-museum/140-...
The first bomb was dropped on August 6. On August 9 the Japanese War Cabinet met in the morning and got confirmation that it was a new type of weapon—and decided to not surrender. They then got news around 13:00 that in the morning a second, similar bomb was dropped, and they—could not decide to surrender or not. The War Cabinet was dead-locked 3–3, so they called in the full Cabinet and it was also dead-locked, and so they called in the Emperor, who broke the dead-lock and decided to 'stop the war'.†
And even after the Emperor himself made the call, there were still elements of the Japanese military that wanted to keep fighting and attempted a coup:
* https://en.wikipedia.org/wiki/Kyūjō_incident
So if it took two bombings (and the Emperor's personal involvement) I'm not sure how people can think zero bombings would have allowed the war to end. (The Japanese had already known for a year before the bombings that they could not win militarily).
The other two options were blockading Japan, causing mass starvation, or an invasion:
* https://en.wikipedia.org/wiki/Operation_Downfall
> […] and think critically about if any creature deserves to be subjected to that
I would think critically about if any creature deserves to be subjected to the being ruled by Imperial Japan given the Rape of Nanking and other things:
* https://en.wikipedia.org/wiki/Nanjing_Massacre
* https://en.wikipedia.org/wiki/Bataan_Death_March
* https://en.wikipedia.org/wiki/Unit_731
† The Japanese do not use the word "surrender" in their announcement: https://en.wikipedia.org/wiki/Hirohito_surrender_broadcast
* https://www.goodreads.com/book/show/51089656-140-days-to-hir...
* https://www.nationalww2museum.org/about-us/notes-museum/140-...
It documents, using Japanese source material including interviews with the principals involved, the decision making process leading up to the eventual surrender.
What was most surprising to me was the reluctance of many members to surrender even after two bombs were dropped. The Emperor himself had to be called in multiple times (which was unprecedented) to ensure that the surrender was 'pushed' through. Even after the vote to surrender happened there were still machinations to overturn it: a reminder that there was a coup attempt to prevent the surrender from being broadcast:
Also perhaps worth noting that after the first bomb the Japanese government was not planning to surrender. The second dropping moved things to a deadlock where half of the ministers—both in the small war council, and the larger full government—wanted to the surrender and the other half did not.
The Emperor had to be called in—an almost unprecedented action—to break the tie. Then, even after the Emperor had made his decision, there was a coup attempt to prevent the "surrender"† broadcast:
* https://en.wikipedia.org/wiki/Kyūjō_incident
I do not know how anyone can think that Japan would have stopped fighting without the bombings when two bombings barely got things over the line.
The book 140 days to Hiroshima by David Dean Barrett goes over the meeting minutes / deliberations and interviews to outline the timeline, and it was not a sure thing that the surrender was going to happen: the hardliners really wanted to keep fighting, and they were ready to go to great lengths to get their way (see Kyūjō above).
The Japanese knew for a year before the bombings that they could not win the war, but they figured that by holding out—causing more causalities of Japanese, Americans, Chinese, Filipinos, etc—the US would lose their resolve and terms could be negotiated so that Japan could (e.g.) keep the land they conquered in Manchuria, etc.
† A word not actually used by the Japanese in the broadcast.