"But people make choices because of their experiences, and the details of their specific situation and circumstances."
You make it sound as if we're organic robots - input circumstances and obtain the computed decision. Such a view makes concepts such as morals and responsibility (and, implicitly, our discussion) irrelevant, inapplicable to humans.
I don't agree with this notion at all.
Hitler rose to power due to economic conditions (partly) - but what did he do with that power?
"Japan itself had become a major world empire in part because of its desire to avoid becoming one of the many oppressed colonies" - and then graduated to doing some oppression ot its own.
I think what the Nasat
was saying is that people have knowledge
(sum of what they've learnt, seen, experienced, done, etc.) and they can take action
or make choices
based on that knowledge (or the application of knowledge).
It doesn't absolve Hitler of his crimes to say that the economic conditions of WWI were a part of his knowledge and experience which was a factor in his later actions. He might well have chosen a different (and peaceful) path given the same knowledge had he applied it differently. (Yes, I believe in free-will insofar as an individual's choices are concerned) Given the same knowledge, someone else in his place might have made a different choice. So he is responsible for his actions. Morality and responsibility are thus very much relevant and applicable to humans as also is experience and circumstance.