I am white and I do not mean for anyone to take this offensively but I find that the use of the word "nigger" by anyone is very inappropriate no matter what context it is used it. I know that many people feel that it is okay to use this word in a joking or affectionate tone, but I've studied American History, Black Studies, and Sociology of Minorities and what I have learned is that it is disrespectful to use a word that degraded so many African Americans during a very horrible time in history. History is very important, without studying history we would be doomed to repeat past mistakes. Society today still has some racism. Although many people feel that it is okay to use this word with their friends to playfully tease or communicate their friendship, I feel that using it in any situation just feeds into the bigger picture of racism in our society. It seems to fuel stereotypes, if people intend it to or not. In order to achieve equality fully, I believe that racial jokes need to end. Children hear this slang and buy into it, thinking that it is okay to talk like this. Their minds are easily molded by what is said and done around them and people continue to talk like this without thinking about where this word came from or what horrifying events people had to go through to not be seen as a "nigger" but instead as what they are, a person, the stereotypes and disrespect to the past will never really end.
I'd like to clarify that I see your main position as such: it is inappropriate to use the word "nigger" in any context. Obviously, since I took up this debate, I disagree. What is appropriate and inappropriate in certain cultures and contexts is subject to those involved. Many people hold the same position when it comes to other derogatory terms, and it is indeed true under many contexts, such as public debate and professional settings; there are situations, however, in which the only harm using such words can do is an illusion that digs itself into many paranoid politically-correct minds. If two friends enjoy referring to themselves and each other as "niggers," the meaning of the word isn't the same as when white supremacists use it. No offence is intended, neither party is offended, and so there is no reason to consider its use inappropriate. The fact that it was used as a derogatory term for black people in the past is history.
Furthermore, you've given an example of a context in which it *is* appropriate to use the word. It is never inappropriate to use the word when talking about history or culture. As long as children aren't involved (as with other derogatory terms), it is okay to use the word when reciting a dialogue, be it from a book or actual event. The only situations in which use of the word "nigger" is inappropriate is when it is meant as an insult or is generally insulting regardless of intent, and there are many many cases where this doesn't apply.