The ideas raised by Enlightenment thinkers were profoundly unsettling and challenging to old regime society and political order.

Answer:

The Enlightenment of the 18th century questioned the intellectual foundations of the Old Regime in Europe. Thinkers such as Locke, Voltaire, Rousseau, Montesquieu and Diderot challenged divine-right monarchy, clerical privilege, aristocratic hierarchy and inherited authority by emphasising reason, liberty, equality and popular sovereignty.

Challenge to Old Regime Society

Attack on privilege:

• Enlightenment thinkers criticised a society based on birth, hereditary status and legal inequality.
• They questioned the special privileges of the nobility and clergy.
• The idea that all individuals possessed natural rights weakened the moral basis of aristocratic privilege.

Criticism of clerical authority:

• Voltaire and other philosophes attacked superstition, intolerance and priestly domination.
• They advocated religious toleration and freedom of thought.
• This challenged the close alliance between Church and monarchy.

Challenge to Political Order

Popular sovereignty:

• Rousseau argued that sovereignty belonged to the people and not to kings.
• This directly challenged divine-right monarchy.
• Political authority now had to be justified by consent, not tradition.

Separation of powers:

• Montesquieu’s idea of separation of powers challenged absolutism.
• It inspired constitutional government and limited monarchy.

Reason and reform:

• Enlightenment thinkers believed that society could be improved through reason, law and education.
• This undermined blind obedience to custom and authority.

Therefore, Enlightenment ideas were unsettling because they attacked the ideological roots of the Old Regime. They did not by themselves cause revolution, but they created the intellectual climate in which monarchy, aristocracy and clerical privilege could be openly questioned.