What is it called when an author uses the thoughts of society to express a character?

Answer: It is called "Soliloquy"

Explanation: A soliloquy is a popular literary device that is often used to reveal the innermost thoughts of a character. Soliloquy is derived from Latin word so meaning "to himself". It is a great technique used to convey the progress of of action of the play by means of expressing character's thoughts about a certain character or past, present, or upcoming event while talking to himself without acknowledging the presence of any other person.

Sociology

Explanation:

means the development / structure of position in community. Therefore the way the society thinks about a character.