The main purpose of the Federalist Papers, written by Alexander Hamilton, James Madison, and John Jay in 1787-1788, was to promote the ratification of the U.S. Constitution. These essays aimed to explain and defend the principles of the new government structure it proposed, including a strong federal government to replace the weaker Articles of Confederation. The Federalist Papers addressed concerns regarding tyranny and provided insights into the necessary checks and balances essential to protect individual liberties. They served as a crucial resource for understanding the framers' intentions and continue to be referenced for constitutional interpretation and legal arguments today.