The conflict that centers in Chris is that of the idealist who thinks things should always be decided by principles (ideas/ideals), the position that he takes, and that of the realist who understands that there aren't always absolutes, that all decisions are made in a context; this is the position that Joe takes.
Sue Bayliss makes the point that Chris' idealism has "wrecked" her husband, making him more interested in research (which doesn't produce much money) and a medical practice which can provide a better income, always wanting people to be better than they can be; she represents one point of view. We see this in Chris' conversation about his troops in the war. He says if they had been a bit more selfish, they might have been home now. On the other hand, Joe was faced with an immediate and practical decision, and he did what he thought was right for his family. His decision is motivated by what he knows of the war ... that no one shipped a tank or a weapon until they got their "price" for it. It's difficult to know if he thought he would be able to catch the cracked cylinder heads and replace them before they were used; but that's not what happened. His decision was not based on ideals/ideas, but on the realities of the moment.
Who was correct? Have to leave that up to you.