Which thinker was known for promoting freedom of speech as a key tool against oppressive government?

Voltaire is recognized for his vigorous advocacy of freedom of speech, viewing it as essential for challenging and resisting tyrannical governance. He famously stated, "I disapprove of what you say, but I will defend to the death your right to say it." This encapsulates his belief in the importance of civil liberties, particularly the freedom of expression, which he considered crucial for fostering enlightenment and progress in society.

His writings often critiqued the status quo and the limitations imposed by both church and state, placing him at the forefront of Enlightenment thinkers who championed individual rights. In contrast, other figures, while significant in their own right, did not emphasize freedom of speech in the same way. For instance, John Locke focused more on government and property rights, Rousseau on the social contract and collective governance, and Hobbes on the necessity of a strong, centralized authority to avoid chaos. Thus, Voltaire stands out as the thinker most closely associated with advocating freedom of speech as a mechanism to challenge oppression.