 As the examples discussed above reveal, a variety of types of empirical evidence are useful to moral theorizing (see also the entries on empirical moral psychology, empirical distributive justice, and empirical psychology and character). Anthropological observation and data have long played a role in moral philosophy. The twentieth-century moral philosophers John Ladd and Richard Brandt investigated moral relativism in part by conducting their own ethnographies in Native American communities. Brandt writes, “We have… a question affecting the truth of ethical relativism which, conceivably, anthropology can help us settle. Does ethnological evidence support the view that ”qualified persons“ can disagree in ethical attitude?” But, he notes, “some kinds of anthropological material will not help us—in particular, bare information about intercultural differences in ethical opinion or attitude.” (1952: 238). This is a caveat frequently cited by philosophers engaged in empirical research: it is important to have philosophers participate in experimental design and the gathering of empirical data, because there are certain questions that must be addressed for the data to have philosophical applications—in this case, whether moral disagreements involve different factual beliefs or other non-moral differences. Barry Hallen (1986, 2000) conducted a series of interviews and ethnographies among the Yoruba, investigating central evaluative concepts and language relating to epistemology, aesthetics, and moral value. Hallen was motivated by questions about the indeterminacy of translation, but his work provides an example of how in-depth interviews can inform investigations of philosophical concepts.