Society collapses after millions lost moral doubts (8)
I believe the answer is:
scruples
'doubts' is the definition.
The definition and answer can be both related to thinking as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
I cannot understand how the remainder of the clue works.
(Other definitions for scruples that I've seen before include "Feelings of doubt arising from conscience" , "Doubts about the morality of an action" , "Qualms" , "Feelings of doubt produced by conscience" , "Feelings of doubt based on conscience" .)