Final answer:
James Madison in Federalist No. 10 argued that the best solution to the problem of factions, or interest groups, was to allow them to flourish and compete, preventing any single group from becoming dominant and promoting democratic pluralism.
Step-by-step explanation:
In Federalist No. 10, James Madison addressed the concerns related to factions and the potential for these groups to hurt public interest. He contended that while factions could present dangers, they should not be limited because doing so would infringe upon individual freedoms. Madison's primary argument was that the best way to handle the mischief of factions was not to remove their causes but to control their effects. In other words, Madison supported a system where interest groups could flourish within a large republic because they would compete against each other, thus preventing any single group from becoming too dominant and abusing its power.
Madison believed that a healthy representative government could manage these factions effectively, ensuring that no single interest would monopolize government attention. This competition among different interests, a concept known as pluralism, would ultimately support democracy and serve the common good by allowing multiple voices to engage in the political process. Therefore, Madison's primary argument in support of what we could call interest groups today corresponds to the claim that these groups would compete against each other, protecting individuals from any one interest becoming too powerful and abusing its power.