Author contends demons are an imaginative product of political expediency.
"…the demonology of William of Auvergne, to determine why and how he constructed his theories out of contemporary lore about demons and other spirits. William was master of theology in the University of Paris and bishop of Paris from 1228 until his death in 1249, in which position he served as a major advisor to the young Louis IX. In addition to being one of the most politically influential people in the French kingdom, William was one of the greatest thinkers of his generation, producing numerous works of theology, philosophy and science.
William’s efforts combine an adoption of an Aristotelian ”physics” for spiritual entities with an uncompromising reaffirmation of the view that demons are evil, fallen angels. He believed that a demonic conspiracy existed to deceive humans into false worship, and his concerns led him to precisely define the capabilities of demons according to the latest scientific views of spirits, to characterize opinions with which he disagreed as demonic lies and to label their holders as demonic dupes. "
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.841.4777&rep=rep1&type=pdf