In this, my last term of teaching, I've decided that it's time to comment on one of your favorite words, a word for which I don't really share your enthusiasm.
That word is "biased."
First (for reference's sake), "bias" is a noun and "biased" is an adjective. A historical author or source might be biased, but cannot be bias. Just so you know.
Second, do you know where the term "bias" really comes from?
Every piece of cloth has a direction in which it likes to move. If you pull cloth in the direction of its bias, it stretches nicely. If you pull it against the bias, it resists. It wants to go in one direction and not to go in another. (It's kind of like the grain in wood - cutting with the grain is easier than cutting against the grain. Meat has a grain, too, and if you cut against the grain, you get short pieces that melt nicely in your mouth; if you cut with the grain, you get longer, rubberier pieces.)
When you say that a historical author has a "bias," you're saying they incline a certain way. They lean in a certain direction. And that's fine, as far as it goes.
The thing is, you inevitably declare that the author is "biased" as if this is all you have to say on the subject - as if discovering "bias" is some form of analysis.
I hate to tell you this, but it's really not. Because if we go back to our cloth analogy: can cloth not have a bias? Not really. The characteristic of inclining in a particular direction is just something that's built into fabric.
It's the same with people. ALL authors are biased in some way. To declare a historical author "biased" is like declaring that a writer uses words. It's kind of a DUH! statement.
Instead, what you need to do is tell me HOW the author EXPRESSES that bias - and specifically, in detail. I don't want you just to tell me that an author is biased in favor of (Christians, the king, their children, Republicans, who/whatever); I want to hear how the author shows that favoritism. What does that actually mean, to be "biased," say, in favor of Christianity? Does that mean the author is willing to lie about/omit matters that make Christianity look bad? Or does it mean the author exaggerates matters that make Christianity look good? Show me what's going on in the text. Something more that just "making Christians look good"; there are LOTS of different ways to make something look good. How does this specific author in this specific text do it? "Good" is an awfully big category - portraying someone as a "good Christian" because they take up arms to defend the weak and helpless, say, is different from portraying someone as a "good Christian" because they pray, fast, and embrace pacifism. Authors make choices about how to portray their subjects (I think Flavia would agree), and if they portray their subject as a veritable Terminator of Christianity, they do so on purpose. That tells us something important about what "Christianity" meant to this society. Which may not be - in fact, probably isn't - the same thing it means to us. Which is the whole point of studying history in the first place.
Finally, because every author is "biased" - because "bias" is inherent to the human condition - being "biased" doesn't mean the same thing as "unreliable" or "inaccurate." In the same way that declaring an author biased is not analysis, dismissing the author as unreliable doesn't work, either. If bias = unreliability, there is no possibility of a reliable author. Of course, if you define "reliable" as "mirror image of the truth," wie es eigentlich gewesen ist, then no, there probably is no possibility of a reliable author. But since then historians would have to sit around twiddling their thumbs lamenting the impossibility of knowing anything, I have to reject that approach. There are some incredibly unreliable authors, from whom we can nonetheless learn a lot. And there some authors who are incredibly reliable. Again, you have to explain how this author is "biased," and demonstrate how that specific expression of bias gets in the way of a reliable account of whatever it is you're reading about. A person who's convinced that they've been abducted by aliens may not be the most reliable commentator on astral phenomenon, but they may be lucidly crystal-clear about the best way to cook beef stroganoff.
So please, my lovely industrious scholars, please stop telling me that a source is "biased." (Although that's preferable to being told that a source is "bias.") Tell me something I don't know already.
Affection and analysis*,
*apologies to profgrrrrl