If he was a good man, how could he leave me? So he must not be a good man. But if he isn't good, then why does it hurt so much to lose him?

Reasonable argument is impossible when authority becomes the arbiter.

You understand that the piggies are animals, and you no more condemn them for murdering Libo and Pipo than you condemn a cabra for shewing up capim." That's right," said Miro. Ender smiled. "And that's why you'll never learn anything from them. Because you think of them as animals.

There's a reason why every human society has fiction. It teaches us how to be 'good,' to behave in a way that is for the benefit of the whole community.

If you give orders and explain nothing, you might get obedience, but you'll get no creativity. If you tell them your purpose, then when your original plan is shown to be faulty, they'll find another way to achieve your goal. Explaining to your men doesn't weaken their respect for you, it proves your respect for them.

But I fear that I also underestimate the stupidity of the rest of mankind. Are we absolutely sure that we ought to win this war?

God, our genes, our environment, or some stupid programmer keying in code at an ancient terminal - there's no way free will can ever exist if we as individuals are the result of some external cause.