Why does the American form of Government Work?

The author of Federalist Essay No. 10  argues that republicanism, not democracy, will result in the best form of government. The author writes, 

“A common passion or interest will, in almost every case, be felt by a majority of the whole; a communication and concert result from the form of government itself; and there is nothing to check the inducements to sacrifice the weaker party or an obnoxious individual. Hence it is that such democracies have ever been spectacles of turbulence and contention; have ever been found incompatible with personal security or the rights of property; and have in general been as short in their lives as they have been violent in their deaths.” 

Everyone has different ideas and opinions, and it’s impossible to demand everyone to think a certain way and expect them to just go along with it. In a democracy, when it comes to making choices based on “majority rules,” decisions are usually focused toward granting a majority’s shared personal interest rather than promoting the greater good of the entire community as a whole. Democracy would eventually split the country apart with all its “turbulence and contention” (definitely something the founding fathers wanted to avoid). However, in a republic, which will

“refine and enlarge the public views, by passing them through the medium of a chosen body of citizens, whose wisdom may best discern the true interest of their country, and whose patriotism and love of justice will be least likely to sacrifice it to temporary or partial considerations. Under such a regulation, it may well happen that the public voice, pronounced by the representatives of the people, will be more consonant to the public good than if pronounced by the people themselves, convened for the purpose.” 

Everyone (except if you’re under 18) still gets a say in government.  However, by having everyone’s public views represented by a smaller, elect groups, decisions are less likely to be centered around personal interests, but rather around what’s best for the country.

The author of Federalist Essay No. 51, who could just be the same guy or guys that wrote Federalist Essay No. 10, explains the necessity in having a separation of powers. 

“It is equally evident, that the members of each department should be as little dependent as possible on those of the others, for the emoluments annexed to their offices. Were the executive magistrate, or the judges, not independent of the legislature in this particular, their independence in every other would be merely nominal. But the great security against a gradual concentration of the several powers in the same department, consists in giving to those who administer each department the necessary constitutional means and personal motives to resist encroachments of the others. The provision for defense must in this, as in all other cases, be made commensurate to the danger of attack. Ambition must be made to counteract ambition. The interest of the man must be connected with the constitutional rights of the place. It may be a reflection on human nature, that such devices should be necessary to control the abuses of government.” 

Dividing the powers into smaller groups that check each other will, again, greatly reduce the likelihood of decisions being centered around personal interests. This is 

“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...It is of great importance in a republic not only to guard the society against the oppression of its rulers, but to guard one part of the society against the injustice of the other part.”

A republican form of government and a separation of powers both focus on dividing up powers into smaller and smaller groups, with the main goal being the generation of just decisions that will benefit the country as a whole. Since America’s government runs on these ideas of a republic and a separation of powers, the American form of government has worked even to this day. But like every other government in the world, it's not perfect, and there's still room for improvement.