The role of bias in historical writing

Are your students enamored of bias? My students are. Everything that might be complicated about a historical source is traced to "bias"--why is an autobiography a troubling source? Because it's hard to separate bias from fact. Why is a novel a difficult source? Because it's hard to separate fact from opinion.

I'm having the students read a challenging tome entitled Reading Primary Sources: The Interpretation of Texts from Nineteenth- and Twentieth-century History.  It is challenging because most of the authors depend upon post-modern theory for their suggestions on how to interpret primary sources. I think the students, if they are unsure what the text is saying, depend upon prior understanding and that screams to look for bias!

This is bugging me for two reasons.
One is that I just read "Primary Sources in History: Breaking Through the Myths" (see my post about it here) and one of the first myths is "historians use a 'sourcing heuristic' to evaluate bias and reliability." The author, Keith Barton, quotes Sean Lang, that "historians do not ask 'Is this source biased?' (which suggests the possibility of unbiased sources), but rather 'What is this source's bias, and how does it add to our picture of the past?'" In Reading Primary Sources, the editors, Benjamin Ziemann and Miriam Dobson, argue that the concept of bias "should be scrapped because it is impossible to get round the structural patterns and material elements of texts which every source genre imposes in a different way. Rather than trying to unearth the hidden but distorted meaning the author has invested in a text, historians should aim to focus on the specific mediality and the inherent structure which are provided by every genre of text."

The second reason it bugs me is because it feels like a parroted response rather than a thought-through one.

I think that this love of "bias" arises from students' discomfort with relativism and the possibility that we cannot know the full and complete "truth" through historical inquiry. I think it also arises because it is easily grasped--look in a source for bias and if you find it, throw it out.

I was very proud of one of my students on Monday, though. He was part of a group presenting on Benjamin Roth's The Great Depression: A Diary and one of his classmates asked if Roth was such a biased Republican whether the diary was worthwhile as a source. The student answered that it depended on what question was being asked of the source (yay! that was the point for the day!). His groupmates immediately replied that, in addition, it was a worthwhile source because there was a lot of objective facts in the diary that could be separated from Roth's bias (sigh).

What do you think is the role of bias in historical writing? How do your students think about it? And is it ok to write about one's current students in a public blog post?