Which French philosopher believed that freedom of speech was the best weapon against bad government?

The belief that freedom of speech serves as the best weapon against bad government is primarily attributed to Voltaire. He was an outspoken advocate for civil liberties and played a pivotal role in promoting the ideals of the Enlightenment, particularly those concerning individual rights and free expression. Voltaire argued that through open discourse and criticism, society could challenge oppressive governments and promote reform. His famous quote, "I disapprove of what you say, but I will defend to the death your right to say it," encapsulates his commitment to the principle of free speech as essential for societal progress and the protection against tyranny.

In contrast, while Rousseau, Diderot, and Hugo contributed significantly to French philosophical and literary thought, their focuses were more varied. Rousseau emphasized concepts such as the social contract and the general will, Diderot is known for his role in the development of the Encyclopédie and ideas about knowledge dissemination, and Hugo is recognized for his literary achievements and social advocacy but did not specifically champion free speech as prominently as Voltaire.