Final answer:
Madison's “double security” concept was to use a system of checks and balances to prevent any single government branch from overpowering the others, thereby ensuring the liberty and justice that are the foundations of government.
Step-by-step explanation:
Madison's concept of “double security” was intended to check the power of the various branches of government and protect the liberties of the people. He asserted this in Federalist #51, explaining that the system of checks and balances detailed in the U.S. Constitution would prevent any one branch from dominating the others. By constructing each branch to have certain powers that could be regulated by the other branches, and creating a system where each branch answers to the authority of the people, Madison believed that justice would be the end result of government actions—thereby preserving liberty.
This concept was influenced by Montesquieu's The Spirit of the Laws, which James Madison, along with other Founding Fathers such as George Washington and Alexander Hamilton, saw as a guiding principle in the framing of a new government. Through the separation of powers and the establishment of a bi-cameral legislature, an independent judiciary, and a separate executive branch, Madison sought to ensure that no single entity could assert too much control, while also maintaining the ability for the federal government to veto state laws when necessary to protect the common interest.