Aritstotle
Thomas Hobbes was a prominent 17th-century English philosopher known for his work in political philosophy. He is best known for his book "Leviathan," where he argues for the necessity of a strong central authority to maintain social order and prevent discord. His ideas have had a significant influence on modern political thought.
"The idea of self-government was set forth by the British philosopher John Locke in his Two Treatises of Government, which had a strong influence on the political leaders of eighteenth-century America." Citation from American Government - Volkomer - page 6
Jean-Jacques Rousseau was a philosopher of the 18th century. His ideologies about the nature of man and his work on the social contract both had major influence on how the American Government runs today.
Harriet Taylor was a philosopher and a Women's right activist. She is died in 1958 due to lung congestion resulted from Syphilis. She is known for exerting considerable influence on her second husband John Stuart Mill, a prominent British philosopher, political economist and civil servant of 19th century.
The term "American century" refers to the belief that the 20th century was dominated by the United States in terms of political, economic, and cultural influence on a global scale. It signifies America's rise to superpower status after World War II and its impact on shaping the world order during that time period.
Your question is too vague. What philosopher made the biggest impact on what? or whom? Ancient Greece? Ronald Reagan? The history of China? Eighteenth-century political thought?
Jean Bodin, a French political philosopher, is often credited with developing the concept of state sovereignty in the 16th century. Bodin argued that the sovereign authority of a state should be indivisible and absolute, enabling the state to make decisions without external interference. His ideas had a significant influence on the development of modern political theory and the idea of nation-states.
Immanuel Kant was an 18th-century German philosopher known for his work on metaphysics, epistemology, ethics, and aesthetics. He is best known for his Critique of Pure Reason, which attempted to reconcile empiricism with rationalism and revolutionized modern philosophy. Kant's ideas have had a profound influence on fields such as ethics, political philosophy, and metaphysics.
Rousseau's mostly direct influence was immediate and on the French Revolution. His ideas of legitimacy through the people, support of a republic, and the use of government to manifest the General Will had a profound impact of how organisers and revolutionaries structured their movement and led the Revolution.
A widespread of interest in conserving soil and natural resources did NOT influence the development of American agriculture during the first half of the 19th century.
Alexis de Tocqueville
Aristotle was a Greek philosopher who lived in the 4th century BCE. He is known for his work in many areas, including metaphysics, ethics, logic, biology, and politics. His writings had a profound influence on Western philosophy and science.