There is not a lot of material in Arthur Miller's Timebends about Tennessee Williams, the other great American playwright of the era. Nonetheless, in one short paragraph, Miller seems to get at something essential about the difference between his worldview and Williams'.
In the late 1940s, Miller became interested in the corruption and brutality that resulted from the Mob control of the Brooklyn waterfront, and sometimes told Williams about what he'd discovered. He writes, "Tennessee, I thought, regarded my interest as remote from him as a writer and yet quite parallel to his lifelong sense of living among the unjust and the cruel. He sat listening to my descriptions of waterfront indignities [... and] seemed moved, although it was particular persons and words that touched him more than any general condition of men."
Miller seems to slightly disapprove of the fact that Williams was more moved by specific stories than by the "general condition" of injustice. But mightn't that be better, for a playwright? We are in the business of dramatizing the lives of "particular persons," after all, not writing journalistic exposés of corruption and exploitation.
I'm not saying it's bad to have a well-developed sense of morality--only that playwrights need to make sure that it doesn't overwhelm the stories they're trying to tell. IMO, Williams' characters are more vivid and memorable than Miller's, and this passage from Timebends suggests why. Though both playwrights often wrote about cruelty, Williams took each instance of cruelty on its own terms, as a matter for human drama; while Miller saw each instance of cruelty as just one more exhibit in the long history of Man's Inhumanity to Man...