Final answer:
The 17th and 18th centuries were the centuries of the philosophes, marking the Age of Enlightenment, a period where thinkers like Voltaire, Rousseau, and Montesquieu advocated for reason and natural law.
Step-by-step explanation:
The two centuries that were the centuries of the philosophes were the 17th and 18th centuries. Philosophers during the Age of Enlightenment, which is often dated from 1685 to 1815, proposed new ways of thinking about governance, society, and the role of reason. This intellectual movement was characterized by a challenge to traditional doctrines, advocating a society based on reason and natural law rather than faith and doctrine, as seen in the work of influential philosophers like Voltaire, Jean-Jacques Rousseau, and Montesquieu.
Montesquieu introduced the concept of separation of powers, which would become a key element in the formation of the United States Constitution. Meanwhile, Voltaire and Rousseau pushed for a new civil order grounded in reason and the natural rights of man. The philosophers of the French Enlightenment played a critical role in influencing the French Revolution, despite many not being revolutionaries themselves. Their forward-thinking ideas encouraged the examination and questioning of traditional institutions and beliefs, which had ramifications across science, politics, and culture.