On a listserv I follow, a poster cited the historian Garry Wills as an authority on Catholic history. Here is the response I posted:
Gary Wills? No. Email needs a gentle sarcasm emoticon. Gary Wills is an example of a phenomenon labelled by anthropologists as 'going native'. Let me explain. Anthropologists do basic research using a technique called participant observation. They live over extended periods of time with the group they are studying, the object being acceptance to a degree that they see and experience things an outsider would miss. At the same time they must keep enough mental distance to retain a social scientific objectivity. Anthropologists all know stories of colleagues who went over this indistinct, shifting line and became members of the group they had set out to study, losing objectivity and becoming defenders, supporters, advocates rather than researchers.
Gary Wills was an excellent historian whose work can be read with profit. Alas however, he did the equivalent to 'going native' for an academic historian. He became an advocate,
supporter, defender for a particular point of view rather than a researcher.
When I began my training as an historian of religion, my first mentor taught that one should study primarily outside your own faith group in order to avoid the temptation to 'go native'. This like most sage advice is most often ignored, but is still wise. Garry Wills's books on American history are highly thought of by fellow academics, but his books on Catholicism are not. He went native and lost the ability to be a good historian.