Which French philosopher emphasized the separation of powers and checks and balances in government?

The philosopher who emphasized the separation of powers and the system of checks and balances in government is Montesquieu. In his influential work "The Spirit of the Laws," Montesquieu argued that political power should not be concentrated in a single entity but instead distributed among separate branches of government—typically, the executive, legislature, and judiciary. This framework was designed to prevent any one branch from becoming too powerful and to provide a system of checks that would hold each branch accountable to the others.

Montesquieu's theories significantly impacted the development of modern democratic governance and inspired the framers of the United States Constitution, who incorporated similar principles of checks and balances into their design of government. This approach aims to safeguard individual liberties and promote fairness within the political system.

The other figures mentioned do not focus primarily on these concepts of government separation and checks. Orwell was a writer known for his political commentary, Tocqueville analyzed democracy in America but did not emphasize the separation of powers in the same foundational way, and Lenin was associated with revolutionary Marxism and centralized government authority.