Several key theories emerged during the Enlightenment period, fundamentally shaping modern thought. Prominent among them were the ideas of rationalism, empiricism, and social contract theory. Philosophers like John Locke advocated for natural rights and government by consent, while Thomas Hobbes viewed a strong central authority as essential for societal order. Voltaire and Montesquieu promoted freedom of speech and the separation of powers, influencing democratic governance. Additionally, theories of human progress and reason challenged traditional authority, paving the way for scientific advancements and social reforms. The Enlightenment laid the intellectual foundation for revolutions and modern governmental systems.