I see your point, and I respect Kant. The problem is, Kant was a philosopher, not a leader. I wonder how well Kant's principles would have held up in the gray world of politics.
I have very great respect for Kant, but disagree with him also, though for different reasons.
Let's pretend Kant was the one deciding how to force a Japanese surrender. Someone comes to him with U.S. Casualty estimates (I've actually heard as high as three million) in one hand, the option to send over a high-altitude bomber to wipe out 50,000 civilians in the other. What would Kant decide was the black or white option? Would he even act, having been floored by something so outside the sheltered world of moral theory?
The black and white option is not to kill. Once you cross that line, for whatever reason, you are allowing your moral landscape to bleed grey. Someone breaks into your house and the only way to keep them from killing you and your family is to kill them. Take the black and white option - you're dead, you're family is dead. But your soul is safe. Not the easy option to take, by any means. But if you kill the intruder, and if you justify this action by saying it was the moral thing to do under the circumstances, you have opened the door for a lot of other exceptions and grey areas.
So Kant probably wouldn't be in the position to make such a decision in the first place [about forcing the Japanese surrender], and if he somehow did find himself in that position, he wouldn't have dropped the bombs.
Now, we know what happened after we dropped the bombs. We don't know, and can never know, what would have happened if we hadn't dropped them. Maybe the estimates and guesses about what would have happened were right on the money, maybe they were way off.
All we know for certain is that dropping the bombs killed a lot of people. And one could argue that that is all we need to know to determine that the people who were behind the decision and action to drop the bombs acted immorally.
It is crucial when considering any morality based upon absolutes to determine its assumptions. If you state that it is morally imperative that you never kill, or never lie, why? One possibility is that your morality is based upon your religion. If you are a Christian, for example, you could take the position that God gave us free will, but he also gave us knowledge of good and evil. Our path to salvation lies in doing good, and leaving the consequences of our actions up to God.
I'm not saying that all absolute moralities believe that killing is always wrong, or that all absolute moralities are based upon religion, or that all Christians believe in free will, doing good, or a black and white morality.
However, I would guess that most absolute moralities have some element of faith behind them, for it would be hard enough for someone to follow such a moral code even if they believed in some sort of supernatural power or cosmic plan, but t would be virtually impossible to follow such a code if you didn't.
Kant strikes me as a wonderful person, as do most great moral philosophers. But I think what they do best is tell us what we should all strive for in moral conduct, not what is necessarily feasible in the course of our lives. Think of Artistotle's stance (I think I've got the right person in mind) on the "ideal" object: We can't make it, as hard as we try, but we should do our best.
I respect Aristotle, too, and like much of what he had to say. And his morality was certainly more amenable to the types of situations one might encounter in the real world. But, and I admit this is somewhat of a cheap shot, Aristotle also "proved" that slavery was a moral practice.
