Final answer:
John Stuart Mill stipulated that the only legitimate use of coercive power in a society is to prevent harm to others. Mill's Harm Principle is central to liberal democratic thought, prioritizing individual freedom while protecting people from harm.
Step-by-step explanation:
According to John Stuart Mill, a philosopher known for his work on liberty and political theory, the only purpose for which power can be rightfully exercised over any member of a civilized community against his will is to prevent harm to others. This principle is famously articulated as the Harm Principle, which posits the idea that an individual's freedom to act may be limited solely in the interest of preventing harm to other members of the community. Mill's assertion emphasizes that an individual's own good, either physical or moral, is not a valid reason for coercive interference by society or the state.
Mill's principle is pivotal in frameworks which advocate for civil liberties and is often referenced in discussions about the role of government and the rights of individuals. His argument stems from a broader philosophy of utilitarianism, which suggests that actions are right if they promote happiness and are wrong if they produce the opposite of happiness, but with the strong caveat that one's freedom ends where others' begin. It is deeply rooted in the idea of individual sovereignty over one's own body and mind, and serves as a foundation for liberal democracies that value both individual freedom and the protection of citizens from mutual harm.