William has come to China for rumored gun power, but what he really needs is trust. Therein lies his vulnerability, even if he views it better not to trust. Yet it could be that he is just afraid; Commander Lin Mae thinks so. The protagonist wants one thing, but in order to get it he must overcome a critical flaw. This is the basic form, or dynamic, of a screenplay. I submit that because film is an excellent medium in which philosophical principles can be explored and wrestled with, the protagonist’s vulnerability, raised to a principle, can efficaciously be more salient in a film than merely in the immediate struggles of the protagonist. In other words, the principle at issue in the protagonist’s flaw can play a more expansive role in a film, deepening it in the process.
The full essay is at "The Great Wall."