In The Ethics of Identity, author and philosopher Kwame Anthony Appiah discusses the doctrines of John Stuart Mill in great detail, so it could be argued that John Stuart Mill is actually the main "character" of the book. Mill was one of the most important English philosophers of the 1800's, and his work analyzes the ramifications of empiricism, which is the doctrine that all knowledge comes from from sense experience. The opposite of empiricism is rationalism, the theory that the mind learns ideas directly and does not need the senses to assist in the process. Mills believed that individuality and self-rule were the bedrock for determining one's identity, and that we have an obligation to behave in a humane and decent way in the lives of other people. Appiah is interested in exploring how our shared communal identities can sometimes affect our individual identities in both positive and negative ways. Appiah also explores the role of both parents and the state in shaping our identities, both collective and individual. Appiah is an advocate for the idea of "rooted cosmopolitanism," which is the thought that one does not deny one's own culture, but rather has an open-minded approach to other cultures and ways of thinking. It is clear that Appiah hopes to appeal to our collective notion of the value of human life to spark discussions that may—in time—promote further understanding between all cultures.