Madison's major idea on this, expressed in such places as the Federalist Papers was that self-interest could be used to ensure liberty and justice. He argued that people were going to act in their own interests. What was needed was a government that was set up to make sure that those "selfish" actions actually helped society. For that reason, Madison wanted a large republic in which the various self-interested factions would cancel one another out. He wanted a government with separation of powers and checks and balances so that the parts of government's self-interest would do the same. In both cases, contending groups acting in their own self-interest would balance one another and liberty and justice would be assured.