In theory, man is a creature of reason. Given a problem, he can
reach an objective and logical solution. I won't deny the existence
of reason or logic. In practice though, logic and reason are not
overly relevant to the behavior of realistic human NPCs. As a crude
model of how to set NPC behavior, I'd suggest that logic and reason
should only be applied after the prejudices of the NPCs culture have
gotten him into so much trouble that his livelihood and income is
threatened. Even then, an INT and EGO check might be required.
Habit is the most important aspect of culture. What problems has a character encountered in his past, his father's past, and his grandfather's? What solutions were applied to these problems? The truly human NPC should solve today's problems using yesterday's solutions.
The cavalry commander is real good at catching Confederate supply trains, and hitting infantry in the flank. Has he ever fought Indians? Courage is the major status trait among the Indian warriors. Whatever solution they might have to their problems, it must involve the youngsters showing their worth. Talking tough with a few dozen cowhands with rifles at his back has always worked for the cattle rancher. What will he do next time someone tries to cross him? Many of the German farmers emigrated after the failed revolutions of 1848. Their ideas of Liberty, Law, Tyranny and Discipline are shaped by their failures in the Old World, as well as the promises made in the New World's Constitution.
The NPC must have a history. What problems did he face in his youth? How did he solve them? What problems did his parents have? How did they solve them? More important still, what are the abstractions made from these past problems? The Revolution and Civil War were fought for 'Freedom' and 'Liberty'. What do these mean to a young black cavalry conscript? Will these concepts at all effect what orders his captain will give him? If the robber baron and the sheriff have both heard of Darwin's "survival of the fittest", will their professions cause them to interpret the concept any differently?
Habit. Culture. The PCs are of course visitors from another realm. Their players are aloof from involvement, and full of 20th century values. It is all too common that a PC will use reason, find a clean and ethical solution, be a hero, and ride off into the sunset.
Does this make the PCs Good? In the pack hunter section, I used 'Good' to indicate an individual who exercised his instincts in moderation, and in such a way to benefit his family and peers. A reasonable, intelligent and habit free PC who applies his clean and ethical solution might also be labeled 'Good', even if the PC violates both human instincts and his culture of origin in solving the conflict. On the other hand, would such a PC really be acting in character in applying 20th century values and solutions to a 19th century game?
In playing an interesting and realistic NPC, reason and logic should be shunned. The Indian chief is not defending his territory so he can feed his family. Such a consideration is of secondary importance. First, he is defending his way of life. Your cattle drive is blocked by barbed wire. Your newly planted wheat is being trampled by cattle. Your newest troopers do not understand how important it is to do things By the Book. Your deputy was shot by a drunken cattleman.
What role has reason in any of this? Reason creates abstract ideas, some of which men are willing to die for. Money. Courage. Free grazing. Holy ground. The Law. The Flag. Looking at any given culture's past, one can see how such concepts can help a culture grow and thrive. This is Good. One can also see how these concepts mix explosively with the status drive of the peer bond, the territorial drive, and the instinctive readiness to see a rival peer group as The Enemy. This can be seen as Evil.
If men contested rationally for resources, compromise would be easy, there would be few conflicts, and the scenario would be boring. Route the train through the valley, but away from the tribe's village and the holy areas. Fence crop areas only, but leave open paths for cattle drives. If the other guy cheats at poker, protest politely.
The cavalry commander lost an arm at Gettysburg, a son at Petersburg, and is not going to lose any more of these goddamned niggers than he absolutely has to. He was also with Burnside's brigade when 'Taps' was first played. Hearing it brings back memories.
God created Man. Mr. Colt made them equal.