The prominent philosopher known for his critiques of political theory in modern thought is John Locke. His ideas, particularly those outlined in "Two Treatises of Government," fundamentally challenged the notion of absolute monarchy and advocated for the concept of individual rights, government by consent, and the social contract. Locke argued that governments derive their legitimacy from the approval of the governed, and that individuals possess natural rights to life, liberty, and property. His influential concepts laid the groundwork for Enlightenment thought and inspired democratic developments, including the American and French Revolutions.