Defending 'snake oil': The preservation of contentious knowledge and practices.

How does belief in controversial ideas persist? I study a community of parents and practitioners who contend that autism spectrum disorder is caused by harmful environmental exposures - notably, early childhood vaccinations - and that there are worthwhile alternative or experimental treatments. Despite objections from dominant experts, these actors maintain their disputed ideas. This study identifies a set of strategies that help maintain internal legitimacy. In particular, actors protect internal legitimacy through professional alignment and contrastive boundary work. Professional alignment mobilizes resemblances to conventional counterparts (i.e. mainstream doctors) to defend unorthodox practices. Meanwhile, contrastive boundary-work performances convey the defining values and strengths that actors associate with their knowledge community and concomitantly, the weaknesses they ascribe to competing groups. Through these activities, actors respond to perceived threats and construct a distinct group identity anchored in shared knowledge, ways of knowing and practice.