Final answer:
Hegemony is the term for the set of widely held assumptions that support an existing society, encompassing the prevailing culture and societal arrangements.
Step-by-step explanation:
The set of widely held assumptions that support an existing society is called hegemony. Hegemony is a concept that embodies not just an ideology, but a powerful ideology widely accepted by multiple groups in society as common sense. This involves an implicit agreement on the norms, values, and beliefs that rationalize and sustain the prevailing social order, encompassing aspects such as the laws, morals, values, religious beliefs, customs, fashions, rituals, and the rules governing social life. The concept of hegemony is linked to the prevailing culture, which consists of shared beliefs and knowledge, influencing human activities and impacting both human and other living systems. It also encompasses societal arrangements, such as legislation, economic systems, and education, which are deeply intertwined with the culture and contribute to society's organization and function.