Final answer:
Thomas Hobbes posits that self-interest is the fundamental reason for human action, as it leads to the formation of a social contract to escape the perilous state of nature and ensure peace, stability, and order under an absolute monarch.
Step-by-step explanation:
According to Thomas Hobbes, the fundamental reason for acting is self-interest. Hobbes believed that in a state of nature without rules and a social contract, life would be 'solitary, poor, nasty, brutish, and short' due to constant competition and fear among individuals. To escape this, people enter into a social contract where they transfer their natural rights and power to a monarch in exchange for peace, stability, and order. This monarch must have absolute authority for effective governance. Therefore, in Hobbesian thought, self-preservation motivates individuals to surrender their freedoms, resulting in a government that is vested with the authority to provide safety and prevent anarchy.