Why does the American form of government work?

The Federalist #51 by James Madison
"In order to lay a due foundation for that separate and distinct exercise of the different powers of government, which to a certain extent is admitted on all hands to be essential to the preservation of liberty, it is evident that each department should have a will of its own; and consequently should be so constituted that the members of each should have as little agency as possible in the appointment of the members of the others."


"We see it particularly displayed in all the subordinate distributions of power, where the constant aim is to divide and arrange the several offices in such a manner as that each may be a check on the other -- that the private interest of every individual may be a sentinel over the public rights. These inventions of prudence cannot be less requisite in the distribution of the supreme powers of the State."

James Madison claims that the United States government works because there is a balance of power between the branches of government. The three branches of federal government are the Executive (the president), Legislative (Senate and House of Representatives), and Judicial (Supreme court and lower courts). A system of checks and balances prevents one branch from gaining too much power. The country is not controlled by an individual ruler, nor one single group of people. Separate branches protect the people from tyranny. The American form of government works because each branch is completely independent of the other branches.   http://www.constitution.org/fed/federa51.htm


The Federalist #10 by James Madison


"Among the numerous advantages promised by a well constructed Union, none deserves to be more accurately developed than its tendency to break and control the violence of faction. The friend of popular governments never finds himself so much alarmed for their character and fate, as when he contemplates their propensity to this dangerous vice."

"By a faction, I understand a number of citizens, whether amounting to a majority or a minority of the whole, who are united and actuated by some common impulse of passion, or of interest, adversed to the rights of other citizens, or to the permanent and aggregate interests of the community."

Madison defines factions as groups of people who band together because of similar interests and beliefs. He believes that these factions are inevitable, as they are a result of an unequal distribution of wealth in America. Since controlling the source of factions would limit liberty, the government must instead control the effects of factions. This is specifically aimed at the poor people of society because they make up a large portion of the population. Madison believes that a large republic will reduce the chances of corruption in government. In a small republic, it is very easy for the people to be fooled. A large republic also stands as an obstacle to factions, because a larger faction cannot be unified. Therefore, Madison is claiming that a large republic is essential to the welfare of the United States. Overall, the main idea of Federalist paper #10 is that there will always be factions, and a large republic is necessary to protect the country from the negative effects of factions. 
http://avalon.law.yale.edu/18th_century/fed10.asp