Final answer:
Liberalism is the first major Western thought theory that emphasizes the idea that the individual is self-sufficient and an individual's freedom is the sole reason for the existence of society.
Step-by-step explanation:
The first major Western thought theory that emphasized the idea that the individual is self-sufficient and an individual's freedom is the sole reason for the existence of society is liberalism. Liberalism is a political philosophy that values individual freedom and emphasizes the rights and autonomy of individuals. It promotes the idea that society should be organized in a way that protects and promotes the individual's rights and freedoms.