From a purely moral point of view, I don't think the morality of the decision to drop bombs on cities is in any way influenced by what actually happened after.

From a purely moral point of view, I don't think the morality of the decision to drop bombs on cities is in any way influenced by what actually happened after. It is only influenced by what happen up to this point and knowledge allies had at that time. Hindsight is 20/20. We do know that it was expected that Japanese will be fighting to the bitter end and it will be difficult to get them to capitulate. But it is not possible to predict the future exactly -- who is to say that the same course of action could not happen after a powerful demonstration without actually dropping bombs on large cities? If you start taking future as excuse for the past you could come to some extreme conclusions.