R. I. Moore’s The War on Heresy is a revisionist take on late medieval heresy, particularly in the lead up to the Albigensian Crusade.
The main argument the book is making is that a lot of the commonplace beliefs about “Cathars” in that era—particularly their well-organized counter-church, and belief in a Manichaean dualism—aren’t actually backed up by much in the way of credible evidence. He goes through case after case, building up the argument that most heresies investigated at the time were some mix of generic apostolic lay reformer anti-clericalism (which he puts into its social and religious context) and political maneuvering (likewise); and goes on to provide plausible explanations for the origin of the by-now long-standing belief in a) an organized group of “Cathar” heretics who b) believed in a consistent theology based around Manichaean precepts.
The book gets a little bit in the weeds as it goes through all these individual cases, but it’s necessary for what it’s trying to do, and Moore mostly keeps it from getting too muddled and repetitive, with a lively writing style. And the picture it draws—of church institutions, heresies, and the various cultures that surrounded them both, from the theological teachings of Paris schools to the strains on social fabric of increasing trade and manufacture—is one that’s vibrant and messy and deeply human, and which sounds honestly a lot more like real history than the picture more usually painted.
Moore’s argument is controversial, and I am not nearly qualified enough to even begin to judge which way the historiographical winds will blow, but I think that even if Moore’s argument ends up being seen as off-base, it paints a picture interesting enough to be worth reading about, and is a useful look at the difficulties of contextualizing and interpreting primary sources.
And plus also, I find it deeply fascinating that stuff I learned in history classes only twenty years ago, basic foundational things that were just taken for granted as needing only explication rather than argument, is now up for debate. You’d think that the events of 800 years ago would be pretty well understood by now, but apparently: nope. No wonder historians are such nihilists about ever knowing the truth about anything.
Recommended, but probably not if this is your first exposure to the Albigensian Crusade and the Cathars; you’ll want to know the conventional take first.