What are two major explanations for why we have a two-party system in the United States? Explain how political parties in Europe are very different from our own. Which party system do you prefer, the one in Europe or in the United States? Why?
The political system established by the "Founding Fathers," as set forth in the Constitution of the United States, is distinct from the parliamentary systems prevalent throughout most of the rest of the democratic world. That the American political system is dominated by two major parties is also a product of the constitutional system established at the nation's founding. Article II of the Constitution establishes the office of the Chief Executive, or president, but stipulates that the president shall be elected by what we know as the Electoral College. Why is that important? Because the system of majority rule embedded within the nation's fabric naturally leads to contests pitting two major political entities against each other. This differs from parliamentary systems where multiple parties compete for seats in the legislature and negotiate arrangements among and with each other in order to be able to form a majority and, consequently, a government.
So, the main reason that the United States is dominated by a two-party system is the requirement for a single political entity or party to win a majority of votes. There is nothing in the Constitution or in law prohibiting the establishment of additional political parties. Indeed, the United States has long maintained more than two parties, including Socialist Workers, Communist, Libertarian, Green, and the Reform Party. (Not sure how the Tea Party fits into this, as it is a subset of the Republican Party.) The Reform Party, until the last election cycle, represented the greatest "threat" to the two-party system by virtue of large-scale disillusionment with the two main parties and by virtue of the financial resources available to that party by its founder and then-presidential candidate Ross Perot. Invariably, however, elections come down to the two main parties facing off: Republicans and Democrats. It is important to note, however, that those two large parties have, from time to time, been characterized internally by competing factions representing divergent perspectives on such matters as fiscal discipline (e.g., the so-called "Blue Dog Democrats" as well as the aforementioned Tea Party).
It could be argued that another main reason for the two-party-dominated political system in the United States is simple inertia. These two political parties exist, are well-resourced financially, and represent platforms that collectively appeal to the overwhelming majority of Americans. As noted, Ross Perot's considerable financial assets did, in the early 1990s, pose a threat to the dominance of the other two major parties. That the Reform Party ultimately failed, however, is a measure of the formidability of the Democratic and Republican establishments as well as the diminished reputation of Mr. Perot within the very limited parameters of electoral politics.
The parliamentary systems prevalent across Europe do represent a viable alternative to the the presidential system established in the Constitution. They are, in a way, more inclusive of political ideologies that fall outside of the major parties. And election of a prime minister usually--not always, but usually--involves individuals with considerable background in governance. Candidates for the position of prime minister almost always have served many years in their countries' legislatures and have risen to the upper ranks of their party establishments. In other words, there is less amateurism. On the flip side, parliamentary systems are less cohesive and more fragile because defections from a governing coalition can cause the fall of a government, with the political instability that entails. Israel provides an excellent example of a parliamentary system fragmented to the point that tiny fringe political parties can wield power disproportionate to their percentage of the parliament because the larger party needs the smaller parties to constitute a majority.
As someone who spent many years working in the Legislative Branch of the U.S. Government, I have often pondered the question of which type of democracy works best. Even when I lean towards a parliamentary system, however, I always come back to the fact that the modern political climate and education systems in the United States no longer produce individuals of the intellectual caliber of the nation's "Founding Fathers." There are no Jeffersons, Adams, Madisons, etc. in the current American political scene. Better to stick with the constitutional framework envisioned by those folks than to risk whatever alternative the two current major parties devised.