Kuran offers a plausible explanation of what happened to ED's knowledge in concert with the social psychology phenomenon of consistency and Lifton's 8 criteria of thought reform.
Preference falsification, according to the economist Timur Kuran, is the act of misrepresenting one’s wants under perceived social pressures. It happens frequently in everyday life, such as when we tell the host of a dinner party that we are enjoying the food when we actually find it bland. In Private Truths, Public Lies, Kuran argues convincingly that the phenomenon not only is ubiquitous but has huge social and political consequences…Kuran provides a unified theory of how preference falsification shapes collective decisions, orients structural change, sustains social stability, distorts human knowledge, and conceals political possibilities.
A common effect of preference falsification is the preservation of widely disliked structures. Another is the conferment of an aura of stability on structures vulnerable to sudden collapse…
In distorting public opinion, preference falsification also corrupts public discourse and, hence, human knowledge. So structures held in place by preference falsification may, if the condition lasts long enough, achieve increasingly genuine acceptance…
http://www.hup.harvard.edu/catalog.php?isbn=9780674707580
Sunstein on How Change Happens. He pulls together three phenomena which social scientists have studied in recent decades: preference falsification, variable thresholds for action, and group polarisation. If Sunstein is to be believed, together these are a cocktail for social shifts that are chaotic and fundamentally unpredictable:
https://80000hours.org/podcast/episodes/cass-sunstein-how-change-happens/