Determine whether a historians political ideology or social ideology would influence the historians

How a person see's what is right or what is wrong will reflect in any creative art they take up. Historians can look at something we see as normal but back in the Renaissance you had to be uptight and proper. 
I think a funny way of looking at your question is to compare a food and imagine two completely different shows about it-
Subject- Bacon
You- LOVE IT
they-HATE IT
Show one-
"Look at the crispy piece a bacon you got there" in a Australian accent.
Show two-
"its bad for your health, its from cute little pigs, the wolf IS OUT THERE!"
...
so basically, if your morally with something thats on your platform, you're going to review it positively, if not, you'll oppose and view it negatively. 
(HW seems so serious now, might as well crack a joke that tries to help)

From there friends or an black doctor