There's a new book out by Princeton philosopher Anthony Appiah, The
Honor Code, in which he argues that immoral cultural habits change
only when they become dishonorable. He uses the examples of dueling,
the Atlantic slave trade, and binding the feet of Chinese women. He
describes how reformers eventually convinced the public that those
practices were dishonorable and should be ridiculed. At that point,
even massive economic self-interest--such as that held by slave traders--could not
block transition to what we would all consider more humane and moral social
norms.